Fuel Pressure and Dead Pedal
#16
Registered User
Thread Starter
I would check directly from the source, the alternator. Maybe this link will help. I know its titled for TC locking/unlocking issues but the APPS and TC both suffer from excessive alternator AC noise, which means this page also applies to what you're after. Mopar1973Man's Dodge Cummins Articles - Torque Converter Lock/Unlock Issues
On another note fuel pressure seems to be getting a litter better, not dropping quite as much under load(still way to much though). I just don't get it
#17
Registered User
I thought I remember the desired level of AC noise being no higher than .020 but I'm not positive anymore. Of course the lower the better. And yes, three bad alternators in a row would be no surprise coming from the major auto parts stores. Sadly the reman parts those places sell is generally garbage. Will you get one which has lower numbers next time?.....not sure.
As for the fuel pressure, what do you mean its better? Did you do something or is it just getting better for no apparent reason?
As for the fuel pressure, what do you mean its better? Did you do something or is it just getting better for no apparent reason?
#18
Registered User
Thread Starter
I thought I remember the desired level of AC noise being no higher than .020 but I'm not positive anymore. Of course the lower the better. And yes, three bad alternators in a row would be no surprise coming from the major auto parts stores. Sadly the reman parts those places sell is generally garbage. Will you get one which has lower numbers next time?.....not sure.
As for the fuel pressure, what do you mean its better? Did you do something or is it just getting better for no apparent reason?
As for the fuel pressure, what do you mean its better? Did you do something or is it just getting better for no apparent reason?
#19
Registered User
If you can get a new one for free then by all means, go for it. I'd keep replacing it until I got some AC numbers I was OK with. But thats me.....
As for the fuel pressure, it sounds like maybe the air is purging out and giving some more solid pressure readings.
And yes, I'd probably replace that APPS too. Again.....if it was me. But you may want to wait and see if a cleaner alternator helps though first to save a buck.
As for the fuel pressure, it sounds like maybe the air is purging out and giving some more solid pressure readings.
And yes, I'd probably replace that APPS too. Again.....if it was me. But you may want to wait and see if a cleaner alternator helps though first to save a buck.
#20
Registered User
Thread Starter
If you can get a new one for free then by all means, go for it. I'd keep replacing it until I got some AC numbers I was OK with. But thats me.....
As for the fuel pressure, it sounds like maybe the air is purging out and giving some more solid pressure readings.
And yes, I'd probably replace that APPS too. Again.....if it was me. But you may want to wait and see if a cleaner alternator helps though first to save a buck.
As for the fuel pressure, it sounds like maybe the air is purging out and giving some more solid pressure readings.
And yes, I'd probably replace that APPS too. Again.....if it was me. But you may want to wait and see if a cleaner alternator helps though first to save a buck.
Thanks again
#21
Registered User
Thread Starter
Update!
Got a few updates and of course, more questions! Today I got may charging system tested by advance auto. Here are the results...
https://cimg5.ibsrv.net/gimg/www.die...31ffca6a34.jpg
http://cimg6.ibsrv.net/gimg/www.dies...beabd09c57.jpg
After seeing those results I am going to let the alt be for now. I know your probably thinking how good does Advance Auto really test and I've thought the same thing, but they aren't going to give me a new one under warranty when there machine says I am good to go.
I also called FASS today and spoke with a Tyler Beck, who was very helpful and gave me a few tests to try before I buy a new lift pump. First he said to check the voltage at the pump, key on, and running. He said I should have about 12.4 at key on and 14.1 with the truck running. I checked the voltage with the pump unplugged and some short pieces of wire jammed into the end of the power cable. I attached my multimeter to the wires with leads with alligator clips. I also conducted the test a few times and with a Fluke and my Extech and got about the same results with the exception that the Extech read slightly higher again.
With Extech:
Key off - 95.5mV
Key on - 13.49V for a split second, then a steady 8.92V
Truck running - climbed from about 12.50V at start to 13.90V steady
With Fluke:
Key off - .108V (a little higher because the key way in i think)
Key on - 0.FL whatever that means, then the 8.84V
Truck Running - climbed to 13.81V steady
The other test he mentioned is to pull fuel from a bucket to make sure the pick up screen in the tank is not clogged. That hardly seems necessary now though.
So my questions are, what do you think of these readings? Do i have an issue since I'm not getting what the FASS rep said I should be (way high then low at key on and low while running)? If so what could be causing these low voltages?? I plan to call FASS back tomorrow and give them my results but I was hoping I could get some info in the mean time.
Thanks in advance!
https://cimg5.ibsrv.net/gimg/www.die...31ffca6a34.jpg
http://cimg6.ibsrv.net/gimg/www.dies...beabd09c57.jpg
After seeing those results I am going to let the alt be for now. I know your probably thinking how good does Advance Auto really test and I've thought the same thing, but they aren't going to give me a new one under warranty when there machine says I am good to go.
I also called FASS today and spoke with a Tyler Beck, who was very helpful and gave me a few tests to try before I buy a new lift pump. First he said to check the voltage at the pump, key on, and running. He said I should have about 12.4 at key on and 14.1 with the truck running. I checked the voltage with the pump unplugged and some short pieces of wire jammed into the end of the power cable. I attached my multimeter to the wires with leads with alligator clips. I also conducted the test a few times and with a Fluke and my Extech and got about the same results with the exception that the Extech read slightly higher again.
With Extech:
Key off - 95.5mV
Key on - 13.49V for a split second, then a steady 8.92V
Truck running - climbed from about 12.50V at start to 13.90V steady
With Fluke:
Key off - .108V (a little higher because the key way in i think)
Key on - 0.FL whatever that means, then the 8.84V
Truck Running - climbed to 13.81V steady
The other test he mentioned is to pull fuel from a bucket to make sure the pick up screen in the tank is not clogged. That hardly seems necessary now though.
So my questions are, what do you think of these readings? Do i have an issue since I'm not getting what the FASS rep said I should be (way high then low at key on and low while running)? If so what could be causing these low voltages?? I plan to call FASS back tomorrow and give them my results but I was hoping I could get some info in the mean time.
Thanks in advance!
#22
Registered User
Those numbers look OK to me. Matter of fact, the initial key on reading should be under 13 volts but I dont see yours being a problem. I think what you're thinking isnt correct is probably more quirky metering tools and bad connections in your testing procedures rather than anything wrong. Also the reason the 13.49 dropped to around 9 volts is because either the grid heater kicked on or the ECM was cycling the fuel pump voltage. Know that the ECM sends alternating voltage signals to the fuel pump while the engine is cranking in order to lower cranking fuel pressure. So as long as you got around 14 volts while the engine was running then you're good.
Dirt in the fuel tank is a logical consideration to changing fuel pressures, and usually there is some slight remanent fine debris left in the fuel filter housing if there's lots of junk in the tank. I'd think there would have to be tons of garbage in there to plug off all inlet supply of fuel though. And if the fuel module in the tank pre-screen is ripped/torn or come loose then you'll find loads of garbage in the fuel filter and housing.
I'd say at this point, when you get your new goodies from Vulcan, install everything, give it a couple days to work the air out and then address any concerns about fuel pressures.
If you're not sure about the alternator then you can get a AC filter and install it in front of the APPS so it reduces noise. I cant remember who has them but if you Google search AC voltage filter you'll probably find what you're after. Plenty of automatic truck guys have installed AC filters to deal with cycling of the torque converter. So you wouldn't be out of line installing one too.
Dirt in the fuel tank is a logical consideration to changing fuel pressures, and usually there is some slight remanent fine debris left in the fuel filter housing if there's lots of junk in the tank. I'd think there would have to be tons of garbage in there to plug off all inlet supply of fuel though. And if the fuel module in the tank pre-screen is ripped/torn or come loose then you'll find loads of garbage in the fuel filter and housing.
I'd say at this point, when you get your new goodies from Vulcan, install everything, give it a couple days to work the air out and then address any concerns about fuel pressures.
If you're not sure about the alternator then you can get a AC filter and install it in front of the APPS so it reduces noise. I cant remember who has them but if you Google search AC voltage filter you'll probably find what you're after. Plenty of automatic truck guys have installed AC filters to deal with cycling of the torque converter. So you wouldn't be out of line installing one too.
#23
Registered User
Thread Starter
Those numbers look OK to me. Matter of fact, the initial key on reading should be under 13 volts but I dont see yours being a problem. I think what you're thinking isnt correct is probably more quirky metering tools and bad connections in your testing procedures rather than anything wrong. Also the reason the 13.49 dropped to around 9 volts is because either the grid heater kicked on or the ECM was cycling the fuel pump voltage. Know that the ECM sends alternating voltage signals to the fuel pump while the engine is cranking in order to lower cranking fuel pressure. So as long as you got around 14 volts while the engine was running then you're good.
Dirt in the fuel tank is a logical consideration to changing fuel pressures, and usually there is some slight remanent fine debris left in the fuel filter housing if there's lots of junk in the tank. I'd think there would have to be tons of garbage in there to plug off all inlet supply of fuel though. And if the fuel module in the tank pre-screen is ripped/torn or come loose then you'll find loads of garbage in the fuel filter and housing.
I'd say at this point, when you get your new goodies from Vulcan, install everything, give it a couple days to work the air out and then address any concerns about fuel pressures.
If you're not sure about the alternator then you can get a AC filter and install it in front of the APPS so it reduces noise. I cant remember who has them but if you Google search AC voltage filter you'll probably find what you're after. Plenty of automatic truck guys have installed AC filters to deal with cycling of the torque converter. So you wouldn't be out of line installing one too.
Dirt in the fuel tank is a logical consideration to changing fuel pressures, and usually there is some slight remanent fine debris left in the fuel filter housing if there's lots of junk in the tank. I'd think there would have to be tons of garbage in there to plug off all inlet supply of fuel though. And if the fuel module in the tank pre-screen is ripped/torn or come loose then you'll find loads of garbage in the fuel filter and housing.
I'd say at this point, when you get your new goodies from Vulcan, install everything, give it a couple days to work the air out and then address any concerns about fuel pressures.
If you're not sure about the alternator then you can get a AC filter and install it in front of the APPS so it reduces noise. I cant remember who has them but if you Google search AC voltage filter you'll probably find what you're after. Plenty of automatic truck guys have installed AC filters to deal with cycling of the torque converter. So you wouldn't be out of line installing one too.
As for the dirt in the fuel tank, I will do like you said and wait and see how everything looks once i get everything from vulcan installed. If i still have issues Im going to try sucking fuel directly from a can. The shop that worked on my truck did replace the fuel level sending unit so it is possible they stirred up something, however I agree with you that it would sure have to be a lot. If that does end up being the case and I have to drop the tank, I think I will add a draw straw. If thats not it, I think I will be getting a new pump from FASS. They quoted me about $305 for a new and improved one today. I asked about rebuilding mine but it would cost almost as much as a new one, especially with shipping.
At this point I'm not even going to install my new APPS. I haven't had anymore problems so I'm almost willing to say it was just a fluke...I really hate to mess with something like that if I don't have to. Knowing my luck I'll replace it and have much bigger problems. I like your suggestion about the filter though. I know you can get them from Geno's so I will keep it in mind if I ever do have bigger problems.
#24
Registered User
Thread Starter
Update
Finally got to drive the truck today after installing my parts from Vulcan. I also relocated my fuel pressure source to under the ff housing by using a tapped 90 and added a snubber there as well. I also used a tapped 90 at the vp and put a Schrader valve there so I still have a test port. Unfortunately my pressures are almost unchanged. Possibly not quite as quick to drop but I noticed that the snubber seems to slow the movement of the gauge quite a bit. And at WOT it still dropped to about 13. That was almost right after starting though...it had been idling but not driven much at that point. Its been about ten miles now though. I was kind of expecting immediate improvement though because when taking everything apart I noticed that the banjo under the ff housing was a little loose and the filter cap wasn't quite totally tight. How long would you wait for pressures to improve before calling FASS for a new pump? Also should the gauge still move at key on with the snubber installed? It hasn't been at this point thats why I ask.
#25
Registered User
The fuel pressure will react a little slower with the snubbers in place as they're restricting the immediate flow volume. Thats normal. The gauge will still move though, and should have always moved too, as soon as the key is turned on. Upon turning the key on, you should see the fuel pressure jump up to normal idle pressure for 2 seconds and then back to zero. If its not then the fuel pump may be weak or air is causing an odd reading. Remember, it may take up to a couple days to get the air out. The air can form tiny bubbles which can be hard to fully purge right away.
Also the fuel pressures will most likely not increase as the air purges the system but what will happen is it will become more stable. The air is causing strange pressure fluctuations for the gauge because air compresses whereas the fuel doesn't. If you're not happy with the overall fuel pressures then give FASS a call and ask them how to increase it. I cant remember if that pump has a replacement spring in the regulator or if you have to stretch the spring. Dont let them tell you what the pressure should be too as its up to you what you want and the pump is more than capable of supplying whatever you set it at, within reason. As long as your supply lines are 3/8" - 1/2" and all the banjo's have been replaced with JIC type fittings then holding at least 15 psi under ALL running conditions is expected. Your fuel pump should be able to maintain a maximum of 5 psi range from idle to WOT, meaning if you set the idle at 19-20 then the WOT should never drop below 15. Unless you're using a high hp box or have huge injectors, but your Smarty is only 65 hp so you should be fine.
Also the fuel pressures will most likely not increase as the air purges the system but what will happen is it will become more stable. The air is causing strange pressure fluctuations for the gauge because air compresses whereas the fuel doesn't. If you're not happy with the overall fuel pressures then give FASS a call and ask them how to increase it. I cant remember if that pump has a replacement spring in the regulator or if you have to stretch the spring. Dont let them tell you what the pressure should be too as its up to you what you want and the pump is more than capable of supplying whatever you set it at, within reason. As long as your supply lines are 3/8" - 1/2" and all the banjo's have been replaced with JIC type fittings then holding at least 15 psi under ALL running conditions is expected. Your fuel pump should be able to maintain a maximum of 5 psi range from idle to WOT, meaning if you set the idle at 19-20 then the WOT should never drop below 15. Unless you're using a high hp box or have huge injectors, but your Smarty is only 65 hp so you should be fine.
#26
Registered User
Thread Starter
The fuel pressure will react a little slower with the snubbers in place as they're restricting the immediate flow volume. Thats normal. The gauge will still move though, and should have always moved too, as soon as the key is turned on. Upon turning the key on, you should see the fuel pressure jump up to normal idle pressure for 2 seconds and then back to zero. If its not then the fuel pump may be weak or air is causing an odd reading. Remember, it may take up to a couple days to get the air out. The air can form tiny bubbles which can be hard to fully purge right away.
Also the fuel pressures will most likely not increase as the air purges the system but what will happen is it will become more stable. The air is causing strange pressure fluctuations for the gauge because air compresses whereas the fuel doesn't. If you're not happy with the overall fuel pressures then give FASS a call and ask them how to increase it. I cant remember if that pump has a replacement spring in the regulator or if you have to stretch the spring. Dont let them tell you what the pressure should be too as its up to you what you want and the pump is more than capable of supplying whatever you set it at, within reason. As long as your supply lines are 3/8" - 1/2" and all the banjo's have been replaced with JIC type fittings then holding at least 15 psi under ALL running conditions is expected. Your fuel pump should be able to maintain a maximum of 5 psi range from idle to WOT, meaning if you set the idle at 19-20 then the WOT should never drop below 15. Unless you're using a high hp box or have huge injectors, but your Smarty is only 65 hp so you should be fine.
Also the fuel pressures will most likely not increase as the air purges the system but what will happen is it will become more stable. The air is causing strange pressure fluctuations for the gauge because air compresses whereas the fuel doesn't. If you're not happy with the overall fuel pressures then give FASS a call and ask them how to increase it. I cant remember if that pump has a replacement spring in the regulator or if you have to stretch the spring. Dont let them tell you what the pressure should be too as its up to you what you want and the pump is more than capable of supplying whatever you set it at, within reason. As long as your supply lines are 3/8" - 1/2" and all the banjo's have been replaced with JIC type fittings then holding at least 15 psi under ALL running conditions is expected. Your fuel pump should be able to maintain a maximum of 5 psi range from idle to WOT, meaning if you set the idle at 19-20 then the WOT should never drop below 15. Unless you're using a high hp box or have huge injectors, but your Smarty is only 65 hp so you should be fine.
Since last night I did find two leaks, one at the tapped 90 at the vp (must not have made it tight enough on the metric adapter) And the ff housing lid seems to be seeping some so I'm going to pull it off, clean it, and replace the o ring on it.
I did stretch the spring in my pump before to bring the idle pressure up from 15 to 19.
Right now my in tank setup is stock and lines to the FASS are stock as far as i know but forward of the FASS is 3/8 the ff housing and then 1/2 from ff housing to vp. All banjos in the supply side are now gone.
I know the smarty is only a max of 65 hp but I do have the 75 hp injectors. I wouldn't think they should be pulling that much for fuel if I'm on Fuel Saver or Stock setting though.
#28
Registered User
Thread Starter
As far as I know, I do not have an in tank pump. Just the FASS. By in tank setup, I just meant the pickup tube and fuel level sending unit...unless an intake pump would draw power through the same plug as the fuel level sending unit? However if I have an in tank pump I would think the shop would have mentioned that when they replaced the fuel level sending unit.
#29
Registered User
I only asked because you said "Right now my in tank setup is stock and lines to the FASS are stock as far as i know but forward of the FASS is 3/8 the ff housing and then 1/2 from ff housing to vp. All banjos in the supply side are now gone."
If a dealer retrofitted and in-tank fuel pump at one time then you would have known because there would have been no engine mounted lift pump on the block but rather a wire loom extension from there running back to the fuel tank.
And if your lines from the tank to the FASS are stock then those metal lines are 5/16" and there has to be a banjo fitting at the FASS inlet if that line from the tank to the FASS is still factory.
Maybe I'm a little confused as to what you really have in your set up.
If a dealer retrofitted and in-tank fuel pump at one time then you would have known because there would have been no engine mounted lift pump on the block but rather a wire loom extension from there running back to the fuel tank.
And if your lines from the tank to the FASS are stock then those metal lines are 5/16" and there has to be a banjo fitting at the FASS inlet if that line from the tank to the FASS is still factory.
Maybe I'm a little confused as to what you really have in your set up.
#30
Registered User
Thread Starter
I only asked because you said "Right now my in tank setup is stock and lines to the FASS are stock as far as i know but forward of the FASS is 3/8 the ff housing and then 1/2 from ff housing to vp. All banjos in the supply side are now gone."
If a dealer retrofitted and in-tank fuel pump at one time then you would have known because there would have been no engine mounted lift pump on the block but rather a wire loom extension from there running back to the fuel tank.
And if your lines from the tank to the FASS are stock then those metal lines are 5/16" and there has to be a banjo fitting at the FASS inlet if that line from the tank to the FASS is still factory.
Maybe I'm a little confused as to what you really have in your set up.
If a dealer retrofitted and in-tank fuel pump at one time then you would have known because there would have been no engine mounted lift pump on the block but rather a wire loom extension from there running back to the fuel tank.
And if your lines from the tank to the FASS are stock then those metal lines are 5/16" and there has to be a banjo fitting at the FASS inlet if that line from the tank to the FASS is still factory.
Maybe I'm a little confused as to what you really have in your set up.