Fuel Pressure and Dead Pedal
10-02-2015, 12:51 PM
#31
Registered User
That makes sense. If the FASS is mounted to the block and you didnt put it there then I'm sure whomever did removed the OEM lift pump on the block and replaced it with the FASS.
Yes the OEM lines are a little small and you're forcing the FASS to suck through a long length of small diameter tubing which isnt going to help the drop in pressure. But nonetheless, 19 psi at idle and 13 psi at WOT isnt the worst by far. Sure it would be nice to get that WOT up a tad but I'm sure you're OK. That said, if you wanted you could increase the idle pressure a little which would offset the WOT pressure some if that would make you feel better. There is NOTHING wrong with running idle fuel pressures above 20 psi. That wives tale rumor is still around but its falsely thrown out there just as much as the "torn diaphragm" rumor.
I run 22-23 psi at idle and around 17 at WOT, and have for years. The thought logic is that its just not necessary to run higher idle pressures if you can achieve a lower idle pressure and still maintain adequate WOT pressures. Hopefully I made that make sense.
Yes the OEM lines are a little small and you're forcing the FASS to suck through a long length of small diameter tubing which isnt going to help the drop in pressure. But nonetheless, 19 psi at idle and 13 psi at WOT isnt the worst by far. Sure it would be nice to get that WOT up a tad but I'm sure you're OK. That said, if you wanted you could increase the idle pressure a little which would offset the WOT pressure some if that would make you feel better. There is NOTHING wrong with running idle fuel pressures above 20 psi. That wives tale rumor is still around but its falsely thrown out there just as much as the "torn diaphragm" rumor.
I run 22-23 psi at idle and around 17 at WOT, and have for years. The thought logic is that its just not necessary to run higher idle pressures if you can achieve a lower idle pressure and still maintain adequate WOT pressures. Hopefully I made that make sense.
10-02-2015, 12:59 PM
#32
Registered User
Thread Starter
That makes sense. If the FASS is mounted to the block and you didnt put it there then I'm sure whomever did removed the OEM lift pump on the block and replaced it with the FASS.
Yes the OEM lines are a little small and you're forcing the FASS to suck through a long length of small diameter tubing which isnt going to help the drop in pressure. But nonetheless, 19 psi at idle and 13 psi at WOT isnt the worst by far. Sure it would be nice to get that WOT up a tad but I'm sure you're OK. That said, if you wanted you could increase the idle pressure a little which would offset the WOT pressure some if that would make you feel better. There is NOTHING wrong with running idle fuel pressures above 20 psi. That wives tale rumor is still around but its falsely thrown out there just as much as the "torn diaphragm" rumor.
I run 22-23 psi at idle and around 17 at WOT, and have for years. The thought logic is that its just not necessary to run higher idle pressures if you can achieve a lower idle pressure and still maintain adequate WOT pressures. Hopefully I made that make sense.
Yes the OEM lines are a little small and you're forcing the FASS to suck through a long length of small diameter tubing which isnt going to help the drop in pressure. But nonetheless, 19 psi at idle and 13 psi at WOT isnt the worst by far. Sure it would be nice to get that WOT up a tad but I'm sure you're OK. That said, if you wanted you could increase the idle pressure a little which would offset the WOT pressure some if that would make you feel better. There is NOTHING wrong with running idle fuel pressures above 20 psi. That wives tale rumor is still around but its falsely thrown out there just as much as the "torn diaphragm" rumor.
I run 22-23 psi at idle and around 17 at WOT, and have for years. The thought logic is that its just not necessary to run higher idle pressures if you can achieve a lower idle pressure and still maintain adequate WOT pressures. Hopefully I made that make sense.
I had heard that about pressures being too high, matter of fact the guy at FASS told me over 20 was too high. I have heard from far more that, like you said, there is nothing wrong with higher pressure. What is the torn diaphragm rumor you mentioned?
10-02-2015, 01:12 PM
#33
Registered User
The torn diaphragm rumor was something that was thought to be the problem for many many VP failures years ago back when these trucks still had factory warranties. Almost 18 years later and we still hear people talk about it.
The VP has three separate chambers and the rotor/distributor is divided via plastic discs. Those discs oscillated back and forth due to the pressure generate inside the VP was greater than the pressure being supplied by the weak OEM lift pumps. Over the years the VP has been greatly upgraded with numerous newly designed components, with the diaphragm getting thicker and covered in metal. That said.....its even questioned as to how legitimate the entire situation was true or if it was merely a tactical response to something they couldnt explain during the mass of problems these trucks were having with the VP's and the lift pumps. Still to this day, no one fully knows.....
OK though, as for the FASS and its location. Since its mounted back by the tank, it could be that someone was using their head and knew that mounting it back there was better due to how fuel pumps like to push fuel rather than suck fuel. Or.....it was because there was an in-tank pump on this truck and they used the existing wire loom already running at the fuel module from a dealer retrofit. That would be worth knowing because if you're sucking through a fuel pump in the fuel module then it will most certainly cause pressure issues for that FASS. Unfortunately the only way to know is to pull the module or maybe take some pictures of the top of the module and the wire connections at the FASS and lets see if someone can identify whether or not they're of the retrofit versions.
The VP has three separate chambers and the rotor/distributor is divided via plastic discs. Those discs oscillated back and forth due to the pressure generate inside the VP was greater than the pressure being supplied by the weak OEM lift pumps. Over the years the VP has been greatly upgraded with numerous newly designed components, with the diaphragm getting thicker and covered in metal. That said.....its even questioned as to how legitimate the entire situation was true or if it was merely a tactical response to something they couldnt explain during the mass of problems these trucks were having with the VP's and the lift pumps. Still to this day, no one fully knows.....
OK though, as for the FASS and its location. Since its mounted back by the tank, it could be that someone was using their head and knew that mounting it back there was better due to how fuel pumps like to push fuel rather than suck fuel. Or.....it was because there was an in-tank pump on this truck and they used the existing wire loom already running at the fuel module from a dealer retrofit. That would be worth knowing because if you're sucking through a fuel pump in the fuel module then it will most certainly cause pressure issues for that FASS. Unfortunately the only way to know is to pull the module or maybe take some pictures of the top of the module and the wire connections at the FASS and lets see if someone can identify whether or not they're of the retrofit versions.
10-02-2015, 01:27 PM
#34
Registered User
Thread Starter
The torn diaphragm rumor was something that was thought to be the problem for many many VP failures years ago back when these trucks still had factory warranties. Almost 18 years later and we still hear people talk about it.
The VP has three separate chambers and the rotor/distributor is divided via plastic discs. Those discs oscillated back and forth due to the pressure generate inside the VP was greater than the pressure being supplied by the weak OEM lift pumps. Over the years the VP has been greatly upgraded with numerous newly designed components, with the diaphragm getting thicker and covered in metal. That said.....its even questioned as to how legitimate the entire situation was true or if it was merely a tactical response to something they couldnt explain during the mass of problems these trucks were having with the VP's and the lift pumps. Still to this day, no one fully knows.....
OK though, as for the FASS and its location. Since its mounted back by the tank, it could be that someone was using their head and knew that mounting it back there was better due to how fuel pumps like to push fuel rather than suck fuel. Or.....it was because there was an in-tank pump on this truck and they used the existing wire loom already running at the fuel module from a dealer retrofit. That would be worth knowing because if you're sucking through a fuel pump in the fuel module then it will most certainly cause pressure issues for that FASS. Unfortunately the only way to know is to pull the module or maybe take some pictures of the top of the module and the wire connections at the FASS and lets see if someone can identify whether or not they're of the retrofit versions.
The VP has three separate chambers and the rotor/distributor is divided via plastic discs. Those discs oscillated back and forth due to the pressure generate inside the VP was greater than the pressure being supplied by the weak OEM lift pumps. Over the years the VP has been greatly upgraded with numerous newly designed components, with the diaphragm getting thicker and covered in metal. That said.....its even questioned as to how legitimate the entire situation was true or if it was merely a tactical response to something they couldnt explain during the mass of problems these trucks were having with the VP's and the lift pumps. Still to this day, no one fully knows.....
OK though, as for the FASS and its location. Since its mounted back by the tank, it could be that someone was using their head and knew that mounting it back there was better due to how fuel pumps like to push fuel rather than suck fuel. Or.....it was because there was an in-tank pump on this truck and they used the existing wire loom already running at the fuel module from a dealer retrofit. That would be worth knowing because if you're sucking through a fuel pump in the fuel module then it will most certainly cause pressure issues for that FASS. Unfortunately the only way to know is to pull the module or maybe take some pictures of the top of the module and the wire connections at the FASS and lets see if someone can identify whether or not they're of the retrofit versions.
10-02-2015, 01:29 PM
#35
Registered User
No, fuel will still flow through the in-tank pump but nothing like if it wasnt there. Also, I dont believe there's a way to remove the in-tank pump from the module either and would require a new module with the pump in it.
10-02-2015, 01:56 PM
#36
Registered User
Thread Starter
Thanks again for all the help!
Dodge Ram Picture by leathermaneod | 4315251 | Diesel Truck Resource
10-02-2015, 04:08 PM
#37
Registered User
Thread Starter
Ok so I just talked to the PO. He said there is no in tank pump so that settles that. 3 questions though. First what exactly does stretching that spring inside the FASS do? And second, my fuel pressure gauge is installed in the bottom pod of the pillar. The isolator is mounted to the power steering lines right by the fuse box under the hood. After the install I was looking over the paperwork from the gauge and it mentioned keeping the isolator at the same height as the gauge. At that point it was in the top pod so I moved it to the bottom but it's still higher than the isolator. The instructions from Geno's hadn't mentioned this and I was already done with no way to put the isolator as high as the gauge so I didn't worry about it. I wonder if that could be the cause of some of my issue? The shop that worked on my truck tested the fp at the vp right after I got it and they said it was 18 under load. Third, have you had any experience with Baldwin fuel filters? I have used the 7777 (7 micron I think) and the 7977 (5 micron). Today I cleaned up the ff housing lid and changed the filter from the 7777 to a 7977 but I didn't leave it in because it went in really hard. And when I pulled it back out it came out so hard that the little seal that makes it fit snug popped of and stayed in the ff housing. Ever experience anything like this? And what are you thoughts on fuel filters in general as far as brand and micron rating. My FASS does not have a filter so I want to filter well but not over do it either as I'm already a little iffy on fuel pressure.
10-02-2015, 04:55 PM
#38
Registered User
Ok so I just talked to the PO. He said there is no in tank pump so that settles that. 3 questions though. First what exactly does stretching that spring inside the FASS do? And second, my fuel pressure gauge is installed in the bottom pod of the pillar. The isolator is mounted to the power steering lines right by the fuse box under the hood. After the install I was looking over the paperwork from the gauge and it mentioned keeping the isolator at the same height as the gauge. At that point it was in the top pod so I moved it to the bottom but it's still higher than the isolator. The instructions from Geno's hadn't mentioned this and I was already done with no way to put the isolator as high as the gauge so I didn't worry about it. I wonder if that could be the cause of some of my issue? The shop that worked on my truck tested the fp at the vp right after I got it and they said it was 18 under load. Third, have you had any experience with Baldwin fuel filters? I have used the 7777 (7 micron I think) and the 7977 (5 micron). Today I cleaned up the ff housing lid and changed the filter from the 7777 to a 7977 but I didn't leave it in because it went in really hard. And when I pulled it back out it came out so hard that the little seal that makes it fit snug popped of and stayed in the ff housing. Ever experience anything like this? And what are you thoughts on fuel filters in general as far as brand and micron rating. My FASS does not have a filter so I want to filter well but not over do it either as I'm already a little iffy on fuel pressure.
Stretching the spring in FASS changes the regulator by placing more pressure on the check ball which is whats regulating how much pressure the fuel pump is allowed to send through the supply line before it bleeds off. Some fuel pumps have adjustable screws which is essentially doing the same thing by placing more pressure on the spring. Some pumps have replaceable springs too but if either is not an option then stretching the spring is all you can do.
I've never heard that you have to have the isolator the same level as the gauge. I cant say how accurate that is either and I'm not sure why it would even be a consideration. Pressure doesnt care which direction its going. But I will say that I detest isolators. I used to be very leery of running raw fuel into the cab and insisted on using an isolator. Went through all the effort and even changed the gauge fuel line from that stupid 1/8" stuff to 1/4" so I could actually work with it and get the coolant in it without making a complete mess or fighting air blocks. Everything worked flawless for about a year and I retained one of the fuel pressure test ports too which gave me the ability to confirm pressures with a test gauge. I cant stress enough how functional that trick is.
Well no matter because after about a year my pressure started to act up. After confirming with the test gauge that the pressure was still as it should be coming from the fuel pump, I eventually found the isolator diaphragm popped in the wrong direction due to a small leak in the gauge side line which allowed the coolant to push out. I fixed the leak and the diaphragm and all was well for about another 6-8 months before the pressure went haywire again. This time I was bored of messing with it..... So I had a section of stainless steel braided line built with JIC -3 ends. Fitted the gauge with a JIC fitting and buttoned it up tight. JIC fittings are fuel safe legal even though the fuel running to the cab is not.
No matter because it works better than it has ever worked and I'm not changing it. In point.....isolators suck and if you research forums, you'll find most others say the same thing. But I couldnt tell you whether or not moving your gauge height would do anything. Doubt it.....If you had someone test the pressure and it was 18 under a load then I would definitely find a way to confirm that yourself. If you dont have one of those factory schrader valve test ports still in place then get another 90* tapped elbow, mount it on the VP and put the test port there. Then buy a fuel pressure test gauge from Vulcan or Genos for about $50. Or go rent one, but just make sure its a good quality one as you want "accurate" readings.
I cant help you on fuel filters either as I only run the OEM micron filter. Every 10k miles or so I replace it with one I've previously ordered from Geno's, or pick on up at NAPA, and go. I've never been caught up in getting the super small micron filters. If it was a "known" or common issue that the OEM filters allow too much debris then I may have a reason to care. You may want to research those two filters too because I've heard that the 7977 has trouble fitting and can actually restrict flow. But these forums are full of odd information too. Maybe the 7977 is only for the 3rd gen trucks.
In regards to the FASS not having a filter, well it doesn't need one. It has a wire screen in the inlet for that "just in case" something large like a small bird happens to come down the line, but other than that there is a very fine pre-screen on the fuel module which weeds out the big stuff. If you're finding loads of small particle debris in the bottom of your fuel filter housing then you may have to wonder if the fuel module screen is damaged. But if it looks fairly clean then your good.
10-02-2015, 09:18 PM
#39
Registered User
Thread Starter
Having the ability to ask the PO is fantastic. That may be useful later on too.
Stretching the spring in FASS changes the regulator by placing more pressure on the check ball which is whats regulating how much pressure the fuel pump is allowed to send through the supply line before it bleeds off. Some fuel pumps have adjustable screws which is essentially doing the same thing by placing more pressure on the spring. Some pumps have replaceable springs too but if either is not an option then stretching the spring is all you can do.
I've never heard that you have to have the isolator the same level as the gauge. I cant say how accurate that is either and I'm not sure why it would even be a consideration. Pressure doesnt care which direction its going. But I will say that I detest isolators. I used to be very leery of running raw fuel into the cab and insisted on using an isolator. Went through all the effort and even changed the gauge fuel line from that stupid 1/8" stuff to 1/4" so I could actually work with it and get the coolant in it without making a complete mess or fighting air blocks. Everything worked flawless for about a year and I retained one of the fuel pressure test ports too which gave me the ability to confirm pressures with a test gauge. I cant stress enough how functional that trick is.
Well no matter because after about a year my pressure started to act up. After confirming with the test gauge that the pressure was still as it should be coming from the fuel pump, I eventually found the isolator diaphragm popped in the wrong direction due to a small leak in the gauge side line which allowed the coolant to push out. I fixed the leak and the diaphragm and all was well for about another 6-8 months before the pressure went haywire again. This time I was bored of messing with it..... So I had a section of stainless steel braided line built with JIC -3 ends. Fitted the gauge with a JIC fitting and buttoned it up tight. JIC fittings are fuel safe legal even though the fuel running to the cab is not. No matter because it works better than it has ever worked and I'm not changing it. In point.....isolators suck and if you research forums, you'll find most others say the same thing. But I couldnt tell you whether or not moving your gauge height would do anything. Doubt it.....
If you had someone test the pressure and it was 18 under a load then I would definitely find a way to confirm that yourself. If you dont have one of those factory schrader valve test ports still in place then get another 90* tapped elbow, mount it on the VP and put the test port there. Then buy a fuel pressure test gauge from Vulcan or Genos for about $50. Or go rent one, but just make sure its a good quality one as you want "accurate" readings.
I cant help you on fuel filters either as I only run the OEM micron filter. Every 10k miles or so I replace it with one I've previously ordered from Geno's, or pick on up at NAPA, and go. I've never been caught up in getting the super small micron filters. If it was a "known" or common issue that the OEM filters allow too much debris then I may have a reason to care. You may want to research those two filters too because I've heard that the 7977 has trouble fitting and can actually restrict flow. But these forums are full of odd information too. Maybe the 7977 is only for the 3rd gen trucks.
In regards to the FASS not having a filter, well it doesn't need one. It has a wire screen in the inlet for that "just in case" something large like a small bird happens to come down the line, but other than that there is a very fine pre-screen on the fuel module which weeds out the big stuff. If you're finding loads of small particle debris in the bottom of your fuel filter housing then you may have to wonder if the fuel module screen is damaged. But if it looks fairly clean then your good.
Stretching the spring in FASS changes the regulator by placing more pressure on the check ball which is whats regulating how much pressure the fuel pump is allowed to send through the supply line before it bleeds off. Some fuel pumps have adjustable screws which is essentially doing the same thing by placing more pressure on the spring. Some pumps have replaceable springs too but if either is not an option then stretching the spring is all you can do.
I've never heard that you have to have the isolator the same level as the gauge. I cant say how accurate that is either and I'm not sure why it would even be a consideration. Pressure doesnt care which direction its going. But I will say that I detest isolators. I used to be very leery of running raw fuel into the cab and insisted on using an isolator. Went through all the effort and even changed the gauge fuel line from that stupid 1/8" stuff to 1/4" so I could actually work with it and get the coolant in it without making a complete mess or fighting air blocks. Everything worked flawless for about a year and I retained one of the fuel pressure test ports too which gave me the ability to confirm pressures with a test gauge. I cant stress enough how functional that trick is.
Well no matter because after about a year my pressure started to act up. After confirming with the test gauge that the pressure was still as it should be coming from the fuel pump, I eventually found the isolator diaphragm popped in the wrong direction due to a small leak in the gauge side line which allowed the coolant to push out. I fixed the leak and the diaphragm and all was well for about another 6-8 months before the pressure went haywire again. This time I was bored of messing with it..... So I had a section of stainless steel braided line built with JIC -3 ends. Fitted the gauge with a JIC fitting and buttoned it up tight. JIC fittings are fuel safe legal even though the fuel running to the cab is not.
No matter because it works better than it has ever worked and I'm not changing it. In point.....isolators suck and if you research forums, you'll find most others say the same thing. But I couldnt tell you whether or not moving your gauge height would do anything. Doubt it.....If you had someone test the pressure and it was 18 under a load then I would definitely find a way to confirm that yourself. If you dont have one of those factory schrader valve test ports still in place then get another 90* tapped elbow, mount it on the VP and put the test port there. Then buy a fuel pressure test gauge from Vulcan or Genos for about $50. Or go rent one, but just make sure its a good quality one as you want "accurate" readings.
I cant help you on fuel filters either as I only run the OEM micron filter. Every 10k miles or so I replace it with one I've previously ordered from Geno's, or pick on up at NAPA, and go. I've never been caught up in getting the super small micron filters. If it was a "known" or common issue that the OEM filters allow too much debris then I may have a reason to care. You may want to research those two filters too because I've heard that the 7977 has trouble fitting and can actually restrict flow. But these forums are full of odd information too. Maybe the 7977 is only for the 3rd gen trucks.
In regards to the FASS not having a filter, well it doesn't need one. It has a wire screen in the inlet for that "just in case" something large like a small bird happens to come down the line, but other than that there is a very fine pre-screen on the fuel module which weeds out the big stuff. If you're finding loads of small particle debris in the bottom of your fuel filter housing then you may have to wonder if the fuel module screen is damaged. But if it looks fairly clean then your good.
I do have a a Schrader. I have two tapped 90s, one at the ff and one at the vp. So I'll have to get a gauge and double check the pressure sometime.
The 9799 is intended for 3rd generation trucks but it is supposed to fit the 2nd generation and people use it because of the finer filtration.
10-02-2015, 10:31 PM
#40
Registered User
This is the test gauge I have. Gauges Accessories - Vulcan - FUEL PRESSURE TEST KIT - VULCAN PERFORMANCE ('98.5-'02, 5.9L) Works great and cheap enough to have laying around for whenever you need it.
The SS line doesnt need to be bled either. You simply hook it up and go and the line self bleeds in short time. The JIC fitting sizes are simply their own size. You dont need to worry about what "size" the JIC fitting is other than the "-" size, but rather you're concern is the pipe thread on the other end of the fitting. But just for sake of comparison, -3 is the same as a 3/16" pipe fitting and -4 is 1/4". NOT in actual inch measurements either but in fitting sizes.....
I chose -3 because the whole fitting is smaller overall and easier to work with in tight spaces, like in the pillar. -4 is just too big. That said, they can fit -3 and -4 on different size hoses. I "think" I remember fitting it to 1/8" Teflon lined SS line. Very strong and resistant to most everything.
What you'd want to look for to connect a -3 SS line to the gauge is a -3 JIC male to a 1/8 NPT. If your gauge has a NPT male end then you'll obviously need a NPT female fitting, or visa versa. Once the pipe end is on then you simply connect the SS line via the JIC fitting. Hopefully I didnt make that too confusing.
Now here's where it gets tricky..... -4 is everywhere but -3 is considered small enough for aftermarket brake line. So for that very reason most places dont custom make -3 lines on sight because of the potential liability from people using them on their brakes. If you can find a place who makes -3 on the spot then great but otherwise you'll have to order it which should take only a couple days. You'll want to measure the length you'll need too, and be generous as you can deal with longer line but too short is too short.
Also for sake of knowing, JIC is what you should have for all the other aftermarket fuel fittings too. None of them are "flare" fittings as JIC has a different flare angle. JIC is 37* and flare is 45*. NOT compatible. The only fittings which are the same as JIC are AN fittings, which stands for Army/Navy and have the same specifications but were built for the military under tighter spec variations. I believe you see AN in colors too and aluminum whereas JIC is usually in steel.
The SS line doesnt need to be bled either. You simply hook it up and go and the line self bleeds in short time. The JIC fitting sizes are simply their own size. You dont need to worry about what "size" the JIC fitting is other than the "-" size, but rather you're concern is the pipe thread on the other end of the fitting. But just for sake of comparison, -3 is the same as a 3/16" pipe fitting and -4 is 1/4". NOT in actual inch measurements either but in fitting sizes.....
I chose -3 because the whole fitting is smaller overall and easier to work with in tight spaces, like in the pillar. -4 is just too big. That said, they can fit -3 and -4 on different size hoses. I "think" I remember fitting it to 1/8" Teflon lined SS line. Very strong and resistant to most everything.
What you'd want to look for to connect a -3 SS line to the gauge is a -3 JIC male to a 1/8 NPT. If your gauge has a NPT male end then you'll obviously need a NPT female fitting, or visa versa. Once the pipe end is on then you simply connect the SS line via the JIC fitting. Hopefully I didnt make that too confusing.
Now here's where it gets tricky..... -4 is everywhere but -3 is considered small enough for aftermarket brake line. So for that very reason most places dont custom make -3 lines on sight because of the potential liability from people using them on their brakes. If you can find a place who makes -3 on the spot then great but otherwise you'll have to order it which should take only a couple days. You'll want to measure the length you'll need too, and be generous as you can deal with longer line but too short is too short.
Also for sake of knowing, JIC is what you should have for all the other aftermarket fuel fittings too. None of them are "flare" fittings as JIC has a different flare angle. JIC is 37* and flare is 45*. NOT compatible. The only fittings which are the same as JIC are AN fittings, which stands for Army/Navy and have the same specifications but were built for the military under tighter spec variations. I believe you see AN in colors too and aluminum whereas JIC is usually in steel.
10-03-2015, 12:46 PM
#41
Registered User
Thread Starter
This is the test gauge I have. Gauges Accessories - Vulcan - FUEL PRESSURE TEST KIT - VULCAN PERFORMANCE ('98.5-'02, 5.9L) Works great and cheap enough to have laying around for whenever you need it.
The SS line doesnt need to be bled either. You simply hook it up and go and the line self bleeds in short time. The JIC fitting sizes are simply their own size. You dont need to worry about what "size" the JIC fitting is other than the "-" size, but rather you're concern is the pipe thread on the other end of the fitting. But just for sake of comparison, -3 is the same as a 3/16" pipe fitting and -4 is 1/4". NOT in actual inch measurements either but in fitting sizes.....
I chose -3 because the whole fitting is smaller overall and easier to work with in tight spaces, like in the pillar. -4 is just too big. That said, they can fit -3 and -4 on different size hoses. I "think" I remember fitting it to 1/8" Teflon lined SS line. Very strong and resistant to most everything.
What you'd want to look for to connect a -3 SS line to the gauge is a -3 JIC male to a 1/8 NPT. If your gauge has a NPT male end then you'll obviously need a NPT female fitting, or visa versa. Once the pipe end is on then you simply connect the SS line via the JIC fitting. Hopefully I didnt make that too confusing.
Now here's where it gets tricky..... -4 is everywhere but -3 is considered small enough for aftermarket brake line. So for that very reason most places dont custom make -3 lines on sight because of the potential liability from people using them on their brakes. If you can find a place who makes -3 on the spot then great but otherwise you'll have to order it which should take only a couple days. You'll want to measure the length you'll need too, and be generous as you can deal with longer line but too short is too short.
Also for sake of knowing, JIC is what you should have for all the other aftermarket fuel fittings too. None of them are "flare" fittings as JIC has a different flare angle. JIC is 37* and flare is 45*. NOT compatible. The only fittings which are the same as JIC are AN fittings, which stands for Army/Navy and have the same specifications but were built for the military under tighter spec variations. I believe you see AN in colors too and aluminum whereas JIC is usually in steel.
The SS line doesnt need to be bled either. You simply hook it up and go and the line self bleeds in short time. The JIC fitting sizes are simply their own size. You dont need to worry about what "size" the JIC fitting is other than the "-" size, but rather you're concern is the pipe thread on the other end of the fitting. But just for sake of comparison, -3 is the same as a 3/16" pipe fitting and -4 is 1/4". NOT in actual inch measurements either but in fitting sizes.....
I chose -3 because the whole fitting is smaller overall and easier to work with in tight spaces, like in the pillar. -4 is just too big. That said, they can fit -3 and -4 on different size hoses. I "think" I remember fitting it to 1/8" Teflon lined SS line. Very strong and resistant to most everything.
What you'd want to look for to connect a -3 SS line to the gauge is a -3 JIC male to a 1/8 NPT. If your gauge has a NPT male end then you'll obviously need a NPT female fitting, or visa versa. Once the pipe end is on then you simply connect the SS line via the JIC fitting. Hopefully I didnt make that too confusing.
Now here's where it gets tricky..... -4 is everywhere but -3 is considered small enough for aftermarket brake line. So for that very reason most places dont custom make -3 lines on sight because of the potential liability from people using them on their brakes. If you can find a place who makes -3 on the spot then great but otherwise you'll have to order it which should take only a couple days. You'll want to measure the length you'll need too, and be generous as you can deal with longer line but too short is too short.
Also for sake of knowing, JIC is what you should have for all the other aftermarket fuel fittings too. None of them are "flare" fittings as JIC has a different flare angle. JIC is 37* and flare is 45*. NOT compatible. The only fittings which are the same as JIC are AN fittings, which stands for Army/Navy and have the same specifications but were built for the military under tighter spec variations. I believe you see AN in colors too and aluminum whereas JIC is usually in steel.
Unless it's just air still...it started harder than usual this morning too. Turned over a few times before it fired like it didn't have the fuel right there where it needed it so maybe there is just a lot of air needing to be worked out. I'm just getting very frustrated with it by now and just want to be sure I don't have to worry about my vp44s health.
10-03-2015, 01:28 PM
#42
Registered User
Thread Starter
Just did another couple of WOT runs, one in 5th gear and one in 4th. In 5th pressure dropped to 13, in 4th pressure dropped to 9!! I wonder if its even possible for air in the line to cause that much of a drop or if this is my indication that the pump is very weak? I may have had a revelation though. It seemed today that the pressure wasn't quite as good as it was yesterday. I think the only things that are different is that I had the leak yesterday, which was caused, i believe, by the schrader valve being slightly pressed in by the the rubber seal inside the cover for it. (maybe a small leaks lets air escape?) And I opened the bleeder screw on the isolator with the truck running to try and bleed air out. I wonder if doing that with the truck running just lets air in rather than bleeding it out? It almost seems like my pressure is better with leaks than without
10-03-2015, 02:35 PM
#43
Registered User
Yes, your pressure drop range is a lot, and to me it sounds like the isolator isnt working like it should resulting in false gauge reading, or that the FASS simply isnt capable of pumping enough volume for your engine. If you're up for it, you could check the inlet screen on the FASS and make sure its not plugged up with debris which would hamper flow.
But that said.....you REALLY need to test your pressure with a test gauge so you can stop guessing and messing with stuff. The more you mess with things on the fuel system, the more chances you have of creating air leaks. And also, the more you mess with things the more air you repeatedly keep allowing in. The air cant purge if you crack open another fitting everyday and allow that air back in.
General rule of thumb is you NEVER want to touch the fuel system/lines/fittings if you dont absolutely have to or unless you're changing fuel filters.
Your extra cranking (or better known as a hard start) is because you already have a leak somewhere in one of the many things you've been messing with on the fuel system. To better explain..... The fuel system does not hold pressure while the engine isnt running, but rather maintains fuel in the lines and VP at all times. This is called the "prime" and if there is a slight leak somewhere in the lines then the fuel will escape down inside the line and back into the fuel tank. Think of a cup of liquid and drinking straw with your finger over the end. Lift the straw out of the cup and the liquid stays in the straw as long as your finger is on the end. Take your finger off the straw or poke a hole in it and the liquid will drain out. Same thing applies to the fuel lines. A sure fire way to tell if this is the problem is to park with the nose of the truck facing downhill because this raises the level of the fuel tank up more in line with the engine and lessens gravity's pull on the fuel. If it starts normal in the morning parked like that then you have a leak. And in case I wasnt cleae, the extra cranking is because the fuel pump must re-fill (re-prime) the system before the engine will start.
But that said.....you REALLY need to test your pressure with a test gauge so you can stop guessing and messing with stuff. The more you mess with things on the fuel system, the more chances you have of creating air leaks. And also, the more you mess with things the more air you repeatedly keep allowing in. The air cant purge if you crack open another fitting everyday and allow that air back in.
General rule of thumb is you NEVER want to touch the fuel system/lines/fittings if you dont absolutely have to or unless you're changing fuel filters.Your extra cranking (or better known as a hard start) is because you already have a leak somewhere in one of the many things you've been messing with on the fuel system. To better explain..... The fuel system does not hold pressure while the engine isnt running, but rather maintains fuel in the lines and VP at all times. This is called the "prime" and if there is a slight leak somewhere in the lines then the fuel will escape down inside the line and back into the fuel tank. Think of a cup of liquid and drinking straw with your finger over the end. Lift the straw out of the cup and the liquid stays in the straw as long as your finger is on the end. Take your finger off the straw or poke a hole in it and the liquid will drain out. Same thing applies to the fuel lines. A sure fire way to tell if this is the problem is to park with the nose of the truck facing downhill because this raises the level of the fuel tank up more in line with the engine and lessens gravity's pull on the fuel. If it starts normal in the morning parked like that then you have a leak. And in case I wasnt cleae, the extra cranking is because the fuel pump must re-fill (re-prime) the system before the engine will start.
10-03-2015, 03:15 PM
#44
Registered User
Thread Starter
Yes, your pressure drop range is a lot, and to me it sounds like the isolator isnt working like it should resulting in false gauge reading, or that the FASS simply isnt capable of pumping enough volume for your engine. If you're up for it, you could check the inlet screen on the FASS and make sure its not plugged up with debris which would hamper flow.
But that said.....you REALLY need to test your pressure with a test gauge so you can stop guessing and messing with stuff. The more you mess with things on the fuel system, the more chances you have of creating air leaks. And also, the more you mess with things the more air you repeatedly keep allowing in. The air cant purge if you crack open another fitting everyday and allow that air back in. General rule of thumb is you NEVER want to touch the fuel system/lines/fittings if you dont absolutely have to or unless you're changing fuel filters.
Your extra cranking (or better known as a hard start) is because you already have a leak somewhere in one of the many things you've been messing with on the fuel system. To better explain..... The fuel system does not hold pressure while the engine isnt running, but rather maintains fuel in the lines and VP at all times. This is called the "prime" and if there is a slight leak somewhere in the lines then the fuel will escape down inside the line and back into the fuel tank. Think of a cup of liquid and drinking straw with your finger over the end. Lift the straw out of the cup and the liquid stays in the straw as long as your finger is on the end. Take your finger off the straw or poke a hole in it and the liquid will drain out. Same thing applies to the fuel lines. A sure fire way to tell if this is the problem is to park with the nose of the truck facing downhill because this raises the level of the fuel tank up more in line with the engine and lessens gravity's pull on the fuel. If it starts normal in the morning parked like that then you have a leak. And in case I wasnt cleae, the extra cranking is because the fuel pump must re-fill (re-prime) the system before the engine will start.
But that said.....you REALLY need to test your pressure with a test gauge so you can stop guessing and messing with stuff. The more you mess with things on the fuel system, the more chances you have of creating air leaks. And also, the more you mess with things the more air you repeatedly keep allowing in. The air cant purge if you crack open another fitting everyday and allow that air back in.
General rule of thumb is you NEVER want to touch the fuel system/lines/fittings if you dont absolutely have to or unless you're changing fuel filters.Your extra cranking (or better known as a hard start) is because you already have a leak somewhere in one of the many things you've been messing with on the fuel system. To better explain..... The fuel system does not hold pressure while the engine isnt running, but rather maintains fuel in the lines and VP at all times. This is called the "prime" and if there is a slight leak somewhere in the lines then the fuel will escape down inside the line and back into the fuel tank. Think of a cup of liquid and drinking straw with your finger over the end. Lift the straw out of the cup and the liquid stays in the straw as long as your finger is on the end. Take your finger off the straw or poke a hole in it and the liquid will drain out. Same thing applies to the fuel lines. A sure fire way to tell if this is the problem is to park with the nose of the truck facing downhill because this raises the level of the fuel tank up more in line with the engine and lessens gravity's pull on the fuel. If it starts normal in the morning parked like that then you have a leak. And in case I wasnt cleae, the extra cranking is because the fuel pump must re-fill (re-prime) the system before the engine will start.
I'm going to get a fuel pressure gauge today. I was under the truck and realized that my FASS is now leaking from the main seal where it fits together. I don't want to buy a new seal for it if I'm going to have to replace it.
I also finally figured out that I have a front axle leak on the passenger side
10-10-2015, 06:08 PM
#45
Registered User
Thread Starter
Update!
Well I had a long busy week but I finally got around to working on the truck again today after not even driving it all week. It started a little hard today but nothing major. It also seemed to not have quite as much "get up and go" but that may just have been in my head.
My fuel pressure gauge arrived from Geno's on thursday so I was finally able to confirm my fuel pressure. First I'd like to say that gauge is sweet! I'd recommend it to anyone to have on hand. It seems that my Autometer fuel pressure gauge reads slightly lower (about 2 psi) than it should. At idle I was reading about 21 psi on the test gauge and about 19 or so on the in cab gauge. I didn't bother running the hose through the firewall to test while driving because that would have been a lot of work. I just compared the two gauges at various rpms. At 3000 rpms my test gauge was reading about 18 while the in cab gauge was reading about 16 (again 2 psi difference so at least its consistent).
After that I tried pulling fuel directly from a can. Pressures on both gauges were almost identical.
Next I pulled off the fitting on the inlet side of the FASS to check the "screen". I don't have a screen in there! I'm guessing its different since its one of the much older models, from 2005(I'll post a picture in my gallery so you can see it). I also noted that it is leaking, not only from the main seam in the body like I stated in a previous post, but also a little bit from the "weep hole". Nothing too major from either but it is leaking. Im wondering if that could be the cause of the hard start? I don't think its enough of a leak to be the cause of the pressure drop. I'm really starting to think its just too worn out to support my 75hp injectors. It went through the fuel in my jug A LOT faster than i expected!
After all that I tested the resistance across the electric motor so that I could have all the information possible. It read between 1 and 1.4 ohms. It started at about .2 but worked its way up to 1.5 then bounced back and forth between 1 and 1.4.
My next step is to email FASS and see what they think of all this. I guess I'll probably be ordering a new lift pump. Any recommendations?
As always I'm anxiously looking forward to your input Katoom!
My fuel pressure gauge arrived from Geno's on thursday so I was finally able to confirm my fuel pressure. First I'd like to say that gauge is sweet! I'd recommend it to anyone to have on hand. It seems that my Autometer fuel pressure gauge reads slightly lower (about 2 psi) than it should. At idle I was reading about 21 psi on the test gauge and about 19 or so on the in cab gauge. I didn't bother running the hose through the firewall to test while driving because that would have been a lot of work. I just compared the two gauges at various rpms. At 3000 rpms my test gauge was reading about 18 while the in cab gauge was reading about 16 (again 2 psi difference so at least its consistent).
After that I tried pulling fuel directly from a can. Pressures on both gauges were almost identical.
Next I pulled off the fitting on the inlet side of the FASS to check the "screen". I don't have a screen in there! I'm guessing its different since its one of the much older models, from 2005(I'll post a picture in my gallery so you can see it). I also noted that it is leaking, not only from the main seam in the body like I stated in a previous post, but also a little bit from the "weep hole". Nothing too major from either but it is leaking. Im wondering if that could be the cause of the hard start? I don't think its enough of a leak to be the cause of the pressure drop. I'm really starting to think its just too worn out to support my 75hp injectors. It went through the fuel in my jug A LOT faster than i expected!
After all that I tested the resistance across the electric motor so that I could have all the information possible. It read between 1 and 1.4 ohms. It started at about .2 but worked its way up to 1.5 then bounced back and forth between 1 and 1.4.
My next step is to email FASS and see what they think of all this. I guess I'll probably be ordering a new lift pump. Any recommendations?
As always I'm anxiously looking forward to your input Katoom!