My lift pump/ CP3 feed solution
09-22-2005, 05:11 PM
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My lift pump/ CP3 feed solution
OK... I'm hearing and seeing more and more people having CP3/lift pump problems. I'm going to share my solution to this situation. First some background...
Understanding the CP3.
The CP3 is a 3 piston metered inlet pump. By metered inlet I mean that the Fuel Control Actuator valve controlled by the ECM meters fuel going into the pumping chambers to control how much fuel the CP3 pumps and thus the engine rail pressure. This is in sharp contrast to other pressure control systems that divert large amounts of PRESSURIZED flow OUT of the pump back to the tank. The FCA meters how much fuel actually gets pressurized in the first place. Very neat and efficient.
In order to meter the fuel into the chambers, the CP3 has an internal metering/lift pump built right into it. This pump takes the fuel at supply pressure and boosts it to pressures between 80 and 180 PSI depending on what is required. This fuel is fed to the FCA via the cascade overflow valve located on the side of the pump.
The cascade overflow valve's (COFV) purpose is to prioritize the fuel flow between the pump itself (ie feed the FCA), then flow excess fuel to the lubrication flows to cool and lubricate the pump and finally divert any flow above that to the return line.
The COFV prioritizes the flow in that order. If the flow rate is low, only the FCA will get fed. No cooling or return flow will be provided. If the flow rate increases, the pump will get cooled. Any more flow than that and some fuel will get sent out the return line. Note that this prioritization happens AFTER the internal supply pump and there is NO passage from the CP3 inlet to the CP3 return line. The inlet feeds the internal supply pump PERIOD. Unlike other pumps where the fuel supply pump inlet may feed the interal cooling passages and make its way back to the return line.
BTW: The Dodge shop manuals say the COFV isn't "field serviceable" I've removed mine, disassembled it and re installed it with no problems.
So... the internal supply pump is a constant displacement gear pump. This pump is actually capable of developing enough suction to draw fuel through a filter right from the tank. It actually does this on Duramax installations.
Being a constant displacement pump means that it you can't hook just any supply pump up to it. Whereas an injection pump like a P7100 can tolerate a large difference in flow rates to/through it with relatively little pressure change, the CP3 cannot. If you try to push too much fuel to the CP3, the pressure will skyrocket. There are no internal relief valves in the CP3, only a direct feed to the supply pump. Conversely, if there isn't enough flow to it, the pressure will drop and the supply pump may actually start developing a vacuum in an attempt to get enough fuel.
Supplying the CP3
Users needn't worry about pushing fuel to a CP3 at a high pressure. Because it has a built in supply pump, the CP3 only needs to be supplied at a low pressure OR VACUUM and it will handle supplying the pumping chambers from there. Whereas previous pumps had to be somewhat pressurized, the CP3 handles its own pressurization.
Conversely, users do have to worry about getting enough fuel to the CP3. Remember the COFV ? It prioritizes the flow and when there isn't enough fuel to the CP3, it shuts off internal lubrication and cooling flow. This is very bad news for the longevity of the CP3. Diesel fuel viscosity and lubricity falls dramatically with an increase in temperature. Hot fuel within the CP3 is bad.
Basically, one needs to get enough fuel from the tank to the CP3 inlet to keep the CP3 well fed, yet not over pressure it doing so.
I get very nervous when I read of users having their inlet fuel pressure at the CP3 falling to zero PSI. While the CP3 is capable of sucking fuel from the tank in the Duramax installation, in the Dodge installation there is a restrictive fuel pump between the CP3 and the tank. Thus when one sees 0 PSI at the inlet of a CP3 in the Dodge, it is or is on the verge of starving.
To date a number of solutions have been tried, with varying results.
I understand the first gen3 Cummins used an engine mounted supply pump. I assume that these pumps had an internal pressure relief valve. The problem with such a setup is that the armatures in those sorts of pump are generally cooled by the fuel itself and if the pump is continually operating in relief mode, the fuel tends to heat up within the pump and overheat it. I've seen the guts of such pumps actually melt when operated continuously at low flow rates and high pressure.
I understand that Dodge then moved the lift pump to the fuel tank. While this is generally a better setup, if the pump is internally pressure relieved it will suffer the same problems.
Some ambitious owners have taken to using a frame mounted pump with an external pressure relief. This is generally a better approach, but suffers from a few problems:
a) although the pumps may have a decent flow rate at low pressures, they often starve the CP3 when asked to pump at higher pressures because their flow rates fall off. Most of these pumps are designed to feed carburetor gasoline engines, where a typical supply pressure might be 2 to 5 PSI. When these types of pumps are turned up to 10 or 15 PSI, their volumes fall off dramatically.
b) the relief valves are often not designed to totally shut off the return flow when the pressure drops. These systems were designed for carburetors, which have floats that will fail when run at higher pressures. In order to avoid over pressure surges the relief valves never fully close. Thus when the CP3 is gulping fuel like crazy and the supply pressure drops, some of the fuel flow is still going back to the tank ! Not great.
So... having these things in mind, I have implemented a fuel system that has worked flawlessly for 3000 miles now.
See the next post for the continuation of this topic.
Understanding the CP3.
The CP3 is a 3 piston metered inlet pump. By metered inlet I mean that the Fuel Control Actuator valve controlled by the ECM meters fuel going into the pumping chambers to control how much fuel the CP3 pumps and thus the engine rail pressure. This is in sharp contrast to other pressure control systems that divert large amounts of PRESSURIZED flow OUT of the pump back to the tank. The FCA meters how much fuel actually gets pressurized in the first place. Very neat and efficient.
In order to meter the fuel into the chambers, the CP3 has an internal metering/lift pump built right into it. This pump takes the fuel at supply pressure and boosts it to pressures between 80 and 180 PSI depending on what is required. This fuel is fed to the FCA via the cascade overflow valve located on the side of the pump.
The cascade overflow valve's (COFV) purpose is to prioritize the fuel flow between the pump itself (ie feed the FCA), then flow excess fuel to the lubrication flows to cool and lubricate the pump and finally divert any flow above that to the return line.
The COFV prioritizes the flow in that order. If the flow rate is low, only the FCA will get fed. No cooling or return flow will be provided. If the flow rate increases, the pump will get cooled. Any more flow than that and some fuel will get sent out the return line. Note that this prioritization happens AFTER the internal supply pump and there is NO passage from the CP3 inlet to the CP3 return line. The inlet feeds the internal supply pump PERIOD. Unlike other pumps where the fuel supply pump inlet may feed the interal cooling passages and make its way back to the return line.
BTW: The Dodge shop manuals say the COFV isn't "field serviceable" I've removed mine, disassembled it and re installed it with no problems.
So... the internal supply pump is a constant displacement gear pump. This pump is actually capable of developing enough suction to draw fuel through a filter right from the tank. It actually does this on Duramax installations.
Being a constant displacement pump means that it you can't hook just any supply pump up to it. Whereas an injection pump like a P7100 can tolerate a large difference in flow rates to/through it with relatively little pressure change, the CP3 cannot. If you try to push too much fuel to the CP3, the pressure will skyrocket. There are no internal relief valves in the CP3, only a direct feed to the supply pump. Conversely, if there isn't enough flow to it, the pressure will drop and the supply pump may actually start developing a vacuum in an attempt to get enough fuel.
Supplying the CP3
Users needn't worry about pushing fuel to a CP3 at a high pressure. Because it has a built in supply pump, the CP3 only needs to be supplied at a low pressure OR VACUUM and it will handle supplying the pumping chambers from there. Whereas previous pumps had to be somewhat pressurized, the CP3 handles its own pressurization.
Conversely, users do have to worry about getting enough fuel to the CP3. Remember the COFV ? It prioritizes the flow and when there isn't enough fuel to the CP3, it shuts off internal lubrication and cooling flow. This is very bad news for the longevity of the CP3. Diesel fuel viscosity and lubricity falls dramatically with an increase in temperature. Hot fuel within the CP3 is bad.
Basically, one needs to get enough fuel from the tank to the CP3 inlet to keep the CP3 well fed, yet not over pressure it doing so.
I get very nervous when I read of users having their inlet fuel pressure at the CP3 falling to zero PSI. While the CP3 is capable of sucking fuel from the tank in the Duramax installation, in the Dodge installation there is a restrictive fuel pump between the CP3 and the tank. Thus when one sees 0 PSI at the inlet of a CP3 in the Dodge, it is or is on the verge of starving.
To date a number of solutions have been tried, with varying results.
I understand the first gen3 Cummins used an engine mounted supply pump. I assume that these pumps had an internal pressure relief valve. The problem with such a setup is that the armatures in those sorts of pump are generally cooled by the fuel itself and if the pump is continually operating in relief mode, the fuel tends to heat up within the pump and overheat it. I've seen the guts of such pumps actually melt when operated continuously at low flow rates and high pressure.
I understand that Dodge then moved the lift pump to the fuel tank. While this is generally a better setup, if the pump is internally pressure relieved it will suffer the same problems.
Some ambitious owners have taken to using a frame mounted pump with an external pressure relief. This is generally a better approach, but suffers from a few problems:
a) although the pumps may have a decent flow rate at low pressures, they often starve the CP3 when asked to pump at higher pressures because their flow rates fall off. Most of these pumps are designed to feed carburetor gasoline engines, where a typical supply pressure might be 2 to 5 PSI. When these types of pumps are turned up to 10 or 15 PSI, their volumes fall off dramatically.
b) the relief valves are often not designed to totally shut off the return flow when the pressure drops. These systems were designed for carburetors, which have floats that will fail when run at higher pressures. In order to avoid over pressure surges the relief valves never fully close. Thus when the CP3 is gulping fuel like crazy and the supply pressure drops, some of the fuel flow is still going back to the tank ! Not great.
So... having these things in mind, I have implemented a fuel system that has worked flawlessly for 3000 miles now.
See the next post for the continuation of this topic.
09-22-2005, 05:13 PM
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The entire fuel system goes like this:
a) stock in tank pick up
b) frame mounted high pressure/high flow inline fuel pump
c) stock fuel filter assembly
c2) optional 10 micron filter element
c3) optional fuel back pressure sensor/telltale
d) CP3
e) CP3 return bypass line
f) stock in tank return line
Keep in mind that this system is implemented on a '99 FORD SUPERDUTY and not a Dodge truck. The implementation details and operation on a Doge should be similar.
Aside: it is funny that Dodge has so many problems with lift pumps given that the supply requirements are relatively benign. For example, most Cummins fuel pumps only need a few PSI of pressure to be adequately supplied. By contrast a PowerStroke diesel engine needs fuel supplied at a pressure of at LEAST 60 PSI or there are issues with inadequate injector filling.
I believe the reason Dodge has had so many lift pump problems is because they are relying on low pressure pumps with internal pressure relief, whereas Ford uses a high pressure BOSCH pump and uses a pressure relief built right into the fuel filter bowl. Anyway... I digress.
The fuel pump in my system is a Walbro GSL392. THIS IS A HIGH PRESSURE FUEL PUMP DESIGNED FOR GASOLINE INJECTION SYSTEMS, but is also tested for diesel. It is interally relieved at about 100 PSI, but will be on the verge of stalling there. This is a gerotor pump. This pump must be used with an external pressure relief. Failure to use a pressure relief on a stock Gen3 engine will result in a cracked fuel filter housing lid. I speak from experience.
The GSL392 pumps 255L/hour at lower pressures and falls off only a bit until it sees 60+ PSI. What this means is that no matter how plugged the fuel filter gets, the GSL will get the fuel to the CP3.
Aside: I'm told the stock Dodge fuel flow spec is 420 ml/ 10 secs, which equates to 150L/hour. So the GSL is more than adequate. It will flow more than this at 70 PSI.
Here is one source of GSL392 pumps: http://www.fuel-pumps.net/inline.html It is a common pump available from lots of sources. Google will find others.
I've been running the pump in my truck for 5 years operating at 60 PSI feeding the Powerstroke that USED TO be in it. No problems whatsoever.
The GSL 392 is a frame mounted pump. I used to have the flow/pressure/supply current curves for it, but I don't have them handy.
The GSL392 connects directly to the stock fuel filter assembly via the stock lines.
The key to my system is the CP3 fuel bypass line. Remember that I said the GSL needs to have an external pressure relief ? And remember that the CP3 has a positive displacement internal pump capable of sucking fuel from a low restriction source ? Well, instead of trying to force feed the CP3 supply pump, I chose to run a high volume of fuel right to the CP3 inlet and let the CP3 supply pump decide how much or how little fuel it needs. This avoids all sorts of problems with over pressuring the CP3 at low flow rates, running a fuel pump at high pressures, under flowing fuel to the CP3 at high fuel rates, etc.
Here is a picture of the bypass line:
So my system works like this:
a) the GSL 392 sucks fuel from the tank via the stock fuel pickup.
b) this fuel is pushed through the stock fuel filter assembly to the CP3 inlet
c) at the CP3 fuel inlet, the CP3 sucks all the fuel it needs into the pump for its use. Thus the interal supply pump is fed at a low positive pressure all the time. It gets as much clean, cool fuel as it needs. The internal supply pump is sized such that if it is properly supplied the CP3 will always have enough flow for good cooling and lubrication
d) at the CP3 fuel inlet, any excess fuel that the CP3 doesn't use is routed to the return line, where it goes harmlessly back to the fuel tank. Furthermore, any excess fuel flow from the CP3 supply pump also goes back to the tank via the return line.
It has the following benefits:
a) simple and relatively inexpensive to implement
b) no worries about running low pressure fuel pumps on their internal pressure reliefs
c) it uses a high pressure/high flow pump that will literally last forever
d) all the fuel pumped goes to the CP3 and there is never a worry about starving the CP3
e) the system operates at low pressure, not over pressuring the CP3, nor requiring it to operate at a significant vacuum.
f) the full pressure capabilities of the high pressure fuel pump are available to push fuel through the fuel filter. And all the fuel flow goes through the filter to the CP3. What this means is that flow to the CP3 does't fall off significantly as the filter gets dirty.
I used a colored plastic bypass line on my CP3. Such line material is not recommend for use in a hot engine compartment although this particular line is rated for fluids to 200F. I used it so that I could see if any air was in the fuel. Incidently, an air bubble sometimes appears when the truck is shut off, but otherwise there is no evidence of air in the fuel. As soon as the pump is started there is no air.
I've had my truck parked and running beside other gen3 Dodge trucks. My engine seems to be smoother and quieter than the others. It might be a coincidence.
I hopes this helps people with CP3/lift pump problems.
a) stock in tank pick up
b) frame mounted high pressure/high flow inline fuel pump
c) stock fuel filter assembly
c2) optional 10 micron filter element
c3) optional fuel back pressure sensor/telltale
d) CP3
e) CP3 return bypass line
f) stock in tank return line
Keep in mind that this system is implemented on a '99 FORD SUPERDUTY and not a Dodge truck. The implementation details and operation on a Doge should be similar.
Aside: it is funny that Dodge has so many problems with lift pumps given that the supply requirements are relatively benign. For example, most Cummins fuel pumps only need a few PSI of pressure to be adequately supplied. By contrast a PowerStroke diesel engine needs fuel supplied at a pressure of at LEAST 60 PSI or there are issues with inadequate injector filling.
I believe the reason Dodge has had so many lift pump problems is because they are relying on low pressure pumps with internal pressure relief, whereas Ford uses a high pressure BOSCH pump and uses a pressure relief built right into the fuel filter bowl. Anyway... I digress.
The fuel pump in my system is a Walbro GSL392. THIS IS A HIGH PRESSURE FUEL PUMP DESIGNED FOR GASOLINE INJECTION SYSTEMS, but is also tested for diesel. It is interally relieved at about 100 PSI, but will be on the verge of stalling there. This is a gerotor pump. This pump must be used with an external pressure relief. Failure to use a pressure relief on a stock Gen3 engine will result in a cracked fuel filter housing lid. I speak from experience.
The GSL392 pumps 255L/hour at lower pressures and falls off only a bit until it sees 60+ PSI. What this means is that no matter how plugged the fuel filter gets, the GSL will get the fuel to the CP3.
Aside: I'm told the stock Dodge fuel flow spec is 420 ml/ 10 secs, which equates to 150L/hour. So the GSL is more than adequate. It will flow more than this at 70 PSI.
Here is one source of GSL392 pumps: http://www.fuel-pumps.net/inline.html It is a common pump available from lots of sources. Google will find others.
I've been running the pump in my truck for 5 years operating at 60 PSI feeding the Powerstroke that USED TO be in it. No problems whatsoever.
The GSL 392 is a frame mounted pump. I used to have the flow/pressure/supply current curves for it, but I don't have them handy.
The GSL392 connects directly to the stock fuel filter assembly via the stock lines.
The key to my system is the CP3 fuel bypass line. Remember that I said the GSL needs to have an external pressure relief ? And remember that the CP3 has a positive displacement internal pump capable of sucking fuel from a low restriction source ? Well, instead of trying to force feed the CP3 supply pump, I chose to run a high volume of fuel right to the CP3 inlet and let the CP3 supply pump decide how much or how little fuel it needs. This avoids all sorts of problems with over pressuring the CP3 at low flow rates, running a fuel pump at high pressures, under flowing fuel to the CP3 at high fuel rates, etc.
Here is a picture of the bypass line:
So my system works like this:
a) the GSL 392 sucks fuel from the tank via the stock fuel pickup.
b) this fuel is pushed through the stock fuel filter assembly to the CP3 inlet
c) at the CP3 fuel inlet, the CP3 sucks all the fuel it needs into the pump for its use. Thus the interal supply pump is fed at a low positive pressure all the time. It gets as much clean, cool fuel as it needs. The internal supply pump is sized such that if it is properly supplied the CP3 will always have enough flow for good cooling and lubrication
d) at the CP3 fuel inlet, any excess fuel that the CP3 doesn't use is routed to the return line, where it goes harmlessly back to the fuel tank. Furthermore, any excess fuel flow from the CP3 supply pump also goes back to the tank via the return line.
It has the following benefits:
a) simple and relatively inexpensive to implement
b) no worries about running low pressure fuel pumps on their internal pressure reliefs
c) it uses a high pressure/high flow pump that will literally last forever
d) all the fuel pumped goes to the CP3 and there is never a worry about starving the CP3
e) the system operates at low pressure, not over pressuring the CP3, nor requiring it to operate at a significant vacuum.
f) the full pressure capabilities of the high pressure fuel pump are available to push fuel through the fuel filter. And all the fuel flow goes through the filter to the CP3. What this means is that flow to the CP3 does't fall off significantly as the filter gets dirty.
I used a colored plastic bypass line on my CP3. Such line material is not recommend for use in a hot engine compartment although this particular line is rated for fluids to 200F. I used it so that I could see if any air was in the fuel. Incidently, an air bubble sometimes appears when the truck is shut off, but otherwise there is no evidence of air in the fuel. As soon as the pump is started there is no air.
I've had my truck parked and running beside other gen3 Dodge trucks. My engine seems to be smoother and quieter than the others. It might be a coincidence.
I hopes this helps people with CP3/lift pump problems.
09-24-2005, 09:18 PM
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Simple but brilliant! I think that would be an excellent solution for the VP44 equipped trucks as well. They have an internal vane pump as well, and in some applications that's what feeds the pump.
09-24-2005, 10:11 PM
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SuperDuty I tip my hat to you sir that is incredible. I learned alot from your extensive detailed post and thank you for all the work involved. I have a question on my fass install. Last time I serviced my truck I drained and changed the stock filter/lift pump which is still in place. I know it's not required but my question is somewhat answered by your post, in that the return lines from the cp3 are routed back to a point on the stock bowl and return to the tank. Is that correct? I don't have a manual but when I drained the bowl diesel also flowed out of the stock line to the cp3 which is disconnected and just sitting there due to the FASS mode. Not alot drained from the line but I was under the impression that the stock filter is bypassed. Anyway question is, does the stock bowl receive fuel returned from the cp3 and also will the fuel heating element in the bowl work heating returned diesel to the tank if this is the flow direction?
09-25-2005, 07:29 PM
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I'm calling the pope right now and nominating you for sainthood. Brilliant solution and obviously well researched, thanks from a guy who just had to have his truck towed to the dealership last night because the only fuel pump runing was the holley blue pump I installed at the tank. My experience now tells me that even though the extra fuel to the lift may help (or maybe not after reading your post), it is not strong enough to push through an inoperative lift pump. A question regarding the banjo fitting conversion shown in your picture, did you drill and tap the originals, or are they a different set up altogether? Also, what size is the hose being used, I'm guessing 1/4" ID, but would like to be sure so I can modify mine after I get it back from the dealer. Thanks again for the informative post.
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09-25-2005, 07:30 PM
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Guys, I just had a 05 FASS 150gph with the pipe pick up in the tank. The reason I think that lift pumps are failing on 3rd gens is the plastic pick up cannister. In mine the plastic cannister which picks up fuel by pulling it up through a plastic mesh filter screen was full of dirt, crud, gelled fuel, etc., over an inch deep. The fuel is picked up 1/4 inch from the lowest part of the tank. (In the FASS we set it up for 1/2 inch from the bottom of the tank. The screen was "varnished" closed except for the mesh closest to the cannister walls. I would avoid using this stock pick up at all cost. The FASS was expensive but it was the best upgrade so far. I can now run 8/9 on the stock turbo (9/9 when up to speed, I'm an SO rem.) no problem. JM2C. KS
09-26-2005, 12:30 AM
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Thanks, guys.
"in that the return lines from the cp3 are routed back to a point on the stock bowl and return to the tank. Is that correct?"
Yes.
"does the stock bowl receive fuel returned from the cp3 and also will the fuel heating element in the bowl work heating returned diesel to the tank if this is the flow direction?"
This is a very interesting question. Here is the deal.
On my 05 engine, the the CP3 return and the rail pressure relief valve both connect to a banjo fitting that screws into the mount for the filter housing. On the other side of the filter housing mount a banjo bolt connecting the drain from the head and the return line are connected. The filter mount has a port connecting only these two banjo bolts and that all this fuel would go directly back to the tank, bypassing the filter. Check your engine and you'll see what a mean.
However, there would be nothing stopping the manufacturer (or us) from machining a port inside the filter housing that connected to the cross port which would allow that fuel to return to the filter. However, this would also allow the fuel pumped from the pump to return to the tank as well. Why would one want to do that ? Because then the pump would supply a high quality volume of fuel to the filter housing and the CP3 could suck as much or little as it desired from the filter housing, essentially doing the same thing as my bypass line, within the filter housing. This would be a neat little mod too. I thought of doing such, but opted for what I did because I plan to put a 10 micron filter into my system and I wanted the bypass as the CP3 rather than in the filter housing.
"thanks from a guy who just had to have his truck towed to the dealership last night because the only fuel pump runing was the holley blue pump I installed at the tank."
It is a shame that the Dodge trucks continue to have lift pump problems. Like I said in my article, the duty a lift pump needs to do on these vehicle is not severe, they are just not tackling the problem with enough understanding. It is kind of like camshaft position sensors on Powerstrokes. Enough to make a grown man cry <especially after it kills his VP44...>.
"My experience now tells me that even though the extra fuel to the lift may help (or maybe not after reading your post), it is not strong enough to push through an inoperative lift pump."
It absolutely isn't. I know this from experience.
"A question regarding the banjo fitting conversion shown in your picture, did you drill and tap the originals, or are they a different set up altogether?"
Drilled and tapped the originals.
"Also, what size is the hose being used, I'm guessing 1/4" ID"
It is 3/16" ID. I thought about going 1/8" ID. Remember that a little backpressure in that bypass line means a little bit more supply pressure to the inlet of the CP3. I only wanted a PSI or so and I though the return line itself would have that.
The fittings themselves are 1/8" NPT. If I remember correctly, I undersized the tap hole a bit and didn't run the tap in quite a far as it should have. The drill removed a little bit of material from the inside of the banjo bolt, but left enough for them to be strong enough to use. I drilled and tapped mine in a lathe. BTW: I drilled them from the head side, not the threaded end. This allowed me to only remove a bit of material where the head attached to the boy, not weakening the whole body.
"Guys, I just had a 05 FASS 150gph with the pipe pick up in the tank. The reason I think that lift pumps are failing on 3rd gens is the plastic pick up cannister. In mine the plastic cannister which picks up fuel by pulling it up through a plastic mesh filter screen was full of dirt, crud, gelled fuel, etc., over an inch deep."
Oh boy... first of all, you need to find a new fuel supplier. There is absolutely no excuse for dirt and crud these days. BTW: when fuel is drawn from a tank, it is replaced with air via the vent. You off road guys might be drawing dusty air into the tank. You might want to consider putting a small air breather filter on your fuel tank vent.
"gelled fuel" What the hell is that ? The only time I ever saw gelled fuel is at -25 and it hasn't been that cold on this continent for 8 months or so.
Secondly, the life of these modern fuel pumps is determined by their operating temperature and the amount of abrasive material found in the fuel they are pumping. Remember how I was saying that the armatures are cooled by fuel ? On some pumps the armatures actually run in fuel. Now throw some gritty debris into that fuel and remember that the brushes are <relatively> soft carbon and tell me how long that armature is going to last... not long. Furthermore, gerotor and vane pumps need to run close clearances. Neither will last with any grit in the fuel.
"The fuel is picked up 1/4 inch from the lowest part of the tank. (In the FASS we set it up for 1/2 inch from the bottom of the tank. The screen was "varnished" closed except for the mesh closest to the cannister walls. I would avoid using this stock pick up at all cost. The FASS was expensive but it was the best upgrade so far."
"Varnished closed" What ? If you've got fuel that will varnish closed the pickup, then the CP3 isn't going to live either. Pull the Cascade overflow valve, disassemble it and look at how small the hole is in the proportioning piston. Do your filters "varnish closed" ?
What sort of pickup does the FASS use ? If you've got that kind of debris in your tank, the only thing that will make a fuel pump survive is a 20ish micron prefilter before the pump. Moving the pickup from 1/4" to 1/2" off the bottom isn't going to do squat. Even moving it 2" off the bottom wouldn't help. The fuel that goes though these electric pumps must be CLEAN.
"in that the return lines from the cp3 are routed back to a point on the stock bowl and return to the tank. Is that correct?"
Yes.
"does the stock bowl receive fuel returned from the cp3 and also will the fuel heating element in the bowl work heating returned diesel to the tank if this is the flow direction?"
This is a very interesting question. Here is the deal.
On my 05 engine, the the CP3 return and the rail pressure relief valve both connect to a banjo fitting that screws into the mount for the filter housing. On the other side of the filter housing mount a banjo bolt connecting the drain from the head and the return line are connected. The filter mount has a port connecting only these two banjo bolts and that all this fuel would go directly back to the tank, bypassing the filter. Check your engine and you'll see what a mean.
However, there would be nothing stopping the manufacturer (or us) from machining a port inside the filter housing that connected to the cross port which would allow that fuel to return to the filter. However, this would also allow the fuel pumped from the pump to return to the tank as well. Why would one want to do that ? Because then the pump would supply a high quality volume of fuel to the filter housing and the CP3 could suck as much or little as it desired from the filter housing, essentially doing the same thing as my bypass line, within the filter housing. This would be a neat little mod too. I thought of doing such, but opted for what I did because I plan to put a 10 micron filter into my system and I wanted the bypass as the CP3 rather than in the filter housing.
"thanks from a guy who just had to have his truck towed to the dealership last night because the only fuel pump runing was the holley blue pump I installed at the tank."
It is a shame that the Dodge trucks continue to have lift pump problems. Like I said in my article, the duty a lift pump needs to do on these vehicle is not severe, they are just not tackling the problem with enough understanding. It is kind of like camshaft position sensors on Powerstrokes. Enough to make a grown man cry <especially after it kills his VP44...>.
"My experience now tells me that even though the extra fuel to the lift may help (or maybe not after reading your post), it is not strong enough to push through an inoperative lift pump."
It absolutely isn't. I know this from experience.
"A question regarding the banjo fitting conversion shown in your picture, did you drill and tap the originals, or are they a different set up altogether?"
Drilled and tapped the originals.
"Also, what size is the hose being used, I'm guessing 1/4" ID"
It is 3/16" ID. I thought about going 1/8" ID. Remember that a little backpressure in that bypass line means a little bit more supply pressure to the inlet of the CP3. I only wanted a PSI or so and I though the return line itself would have that.
The fittings themselves are 1/8" NPT. If I remember correctly, I undersized the tap hole a bit and didn't run the tap in quite a far as it should have. The drill removed a little bit of material from the inside of the banjo bolt, but left enough for them to be strong enough to use. I drilled and tapped mine in a lathe. BTW: I drilled them from the head side, not the threaded end. This allowed me to only remove a bit of material where the head attached to the boy, not weakening the whole body.
"Guys, I just had a 05 FASS 150gph with the pipe pick up in the tank. The reason I think that lift pumps are failing on 3rd gens is the plastic pick up cannister. In mine the plastic cannister which picks up fuel by pulling it up through a plastic mesh filter screen was full of dirt, crud, gelled fuel, etc., over an inch deep."
Oh boy... first of all, you need to find a new fuel supplier. There is absolutely no excuse for dirt and crud these days. BTW: when fuel is drawn from a tank, it is replaced with air via the vent. You off road guys might be drawing dusty air into the tank. You might want to consider putting a small air breather filter on your fuel tank vent.
"gelled fuel" What the hell is that ? The only time I ever saw gelled fuel is at -25 and it hasn't been that cold on this continent for 8 months or so.
Secondly, the life of these modern fuel pumps is determined by their operating temperature and the amount of abrasive material found in the fuel they are pumping. Remember how I was saying that the armatures are cooled by fuel ? On some pumps the armatures actually run in fuel. Now throw some gritty debris into that fuel and remember that the brushes are <relatively> soft carbon and tell me how long that armature is going to last... not long. Furthermore, gerotor and vane pumps need to run close clearances. Neither will last with any grit in the fuel.
"The fuel is picked up 1/4 inch from the lowest part of the tank. (In the FASS we set it up for 1/2 inch from the bottom of the tank. The screen was "varnished" closed except for the mesh closest to the cannister walls. I would avoid using this stock pick up at all cost. The FASS was expensive but it was the best upgrade so far."
"Varnished closed" What ? If you've got fuel that will varnish closed the pickup, then the CP3 isn't going to live either. Pull the Cascade overflow valve, disassemble it and look at how small the hole is in the proportioning piston. Do your filters "varnish closed" ?
What sort of pickup does the FASS use ? If you've got that kind of debris in your tank, the only thing that will make a fuel pump survive is a 20ish micron prefilter before the pump. Moving the pickup from 1/4" to 1/2" off the bottom isn't going to do squat. Even moving it 2" off the bottom wouldn't help. The fuel that goes though these electric pumps must be CLEAN.
09-26-2005, 10:44 AM
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I obviously can't speak for Dodge, but I'm not sure I am comfortable with the setup on the Duramax. I like having a pusher pump close to the tank. I wonder how well the Duramax setup works when the filter gets a bit dirty. I'd much rather have a pressurized system than a vacuum system for moving fuel longer distances and through restrictive filters.
09-26-2005, 10:42 PM
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"Guys, I just had a 05 FASS 150gph with the pipe pick up in the tank. The reason I think that lift pumps are failing on 3rd gens is the plastic pick up cannister. In mine the plastic cannister which picks up fuel by pulling it up through a plastic mesh filter screen was full of dirt, crud, gelled fuel, etc., over an inch deep."
I haven't seen a clean fuel nozzle at a fuel stop yet. Alot of dirt is getting in on dirty nozzles during fueling. I wipe off the nozzle when I do it but I don't always get to do it.
Oh boy... first of all, you need to find a new fuel supplier. There is absolutely no excuse for dirt and crud these days. BTW: when fuel is drawn from a tank, it is replaced with air via the vent. You off road guys might be drawing dusty air into the tank. You might want to consider putting a small air breather filter on your fuel tank vent.
Thats a great idea to cut down on airborne dust
"gelled fuel" What the hell is that ? The only time I ever saw gelled fuel is at -25 and it hasn't been that cold on this continent for 8 months or so.
You're right a better description would have gelled material in the fuel. what can I say it was like clear jello. Maybe it was water and some of the fuel conditioner that had accumulated. It was there and it was foul.
Secondly, the life of these modern fuel pumps is determined by their operating temperature and the amount of abrasive material found in the fuel they are pumping. Remember how I was saying that the armatures are cooled by fuel ? On some pumps the armatures actually run in fuel. Now throw some gritty debris into that fuel and remember that the brushes are <relatively> soft carbon and tell me how long that armature is going to last... not long. Furthermore, gerotor and vane pumps need to run close clearances. Neither will last with any grit in the fuel.
If the fuel supply is blocked off by a plugged in tank filter screen then the pump will be trying to suck vacuum all the time with little or no flow. By the end of it I couldn't run stock without running out of fuel and could only get 20 pounds of boost at WOT before it would cut out.
"The fuel is picked up 1/4 inch from the lowest part of the tank. (In the FASS we set it up for 1/2 inch from the bottom of the tank. The screen was "varnished" closed except for the mesh closest to the cannister walls. I would avoid using this stock pick up at all cost. The FASS was expensive but it was the best upgrade so far."
In Canada we burn lots of diesel ...even to warm our homes and heat our water. I have yet to see a fuel tank that didn't accumulate a layer of crud in it when the tank was not bottom outlet. When you checked your tank was the tank and the pick up clean? Does diesel float on water?
"Varnished closed" What ? If you've got fuel that will varnish closed the pickup, then the CP3 isn't going to live either. Pull the Cascade overflow valve, disassemble it and look at how small the hole is in the proportioning piston. Do your filters "varnish closed" ?
By "varnished" I meant that it was plugged with a resin like substance that gave the look of being varnished closed. The cannister had diesel in it and the diesel flowed out of the cannister so slow that we had to dump the contents out as it wouldn't drain. Nuff description I hope
The FASS uses approx. 3/4 inch id pipe to pick up fuel in the tank where it is sucked through a 10 micron filter (or less) on the fass assembly. It then filters out the "micro bubbles of air" that are only visible under magnification but that get entrapped in the diesel by being pumped back into the tank with air and constant sloshing of the fuel.
Long and Short of it is I've gone from less than 24 psi boost and mild EGT's to 34 psi (39 peak psi) mild Hot EGT's and a ton more power. My mileage on the overhead is back to being accurate also, but unfortunately it is lower empty 
but better towing you win some you lose some.
I haven't seen a clean fuel nozzle at a fuel stop yet. Alot of dirt is getting in on dirty nozzles during fueling. I wipe off the nozzle when I do it but I don't always get to do it.
Oh boy... first of all, you need to find a new fuel supplier. There is absolutely no excuse for dirt and crud these days. BTW: when fuel is drawn from a tank, it is replaced with air via the vent. You off road guys might be drawing dusty air into the tank. You might want to consider putting a small air breather filter on your fuel tank vent.
Thats a great idea to cut down on airborne dust
"gelled fuel" What the hell is that ? The only time I ever saw gelled fuel is at -25 and it hasn't been that cold on this continent for 8 months or so.
You're right a better description would have gelled material in the fuel. what can I say it was like clear jello. Maybe it was water and some of the fuel conditioner that had accumulated. It was there and it was foul.
Secondly, the life of these modern fuel pumps is determined by their operating temperature and the amount of abrasive material found in the fuel they are pumping. Remember how I was saying that the armatures are cooled by fuel ? On some pumps the armatures actually run in fuel. Now throw some gritty debris into that fuel and remember that the brushes are <relatively> soft carbon and tell me how long that armature is going to last... not long. Furthermore, gerotor and vane pumps need to run close clearances. Neither will last with any grit in the fuel.
If the fuel supply is blocked off by a plugged in tank filter screen then the pump will be trying to suck vacuum all the time with little or no flow. By the end of it I couldn't run stock without running out of fuel and could only get 20 pounds of boost at WOT before it would cut out.
"The fuel is picked up 1/4 inch from the lowest part of the tank. (In the FASS we set it up for 1/2 inch from the bottom of the tank. The screen was "varnished" closed except for the mesh closest to the cannister walls. I would avoid using this stock pick up at all cost. The FASS was expensive but it was the best upgrade so far."
In Canada we burn lots of diesel ...even to warm our homes and heat our water. I have yet to see a fuel tank that didn't accumulate a layer of crud in it when the tank was not bottom outlet. When you checked your tank was the tank and the pick up clean? Does diesel float on water?
"Varnished closed" What ? If you've got fuel that will varnish closed the pickup, then the CP3 isn't going to live either. Pull the Cascade overflow valve, disassemble it and look at how small the hole is in the proportioning piston. Do your filters "varnish closed" ?
By "varnished" I meant that it was plugged with a resin like substance that gave the look of being varnished closed. The cannister had diesel in it and the diesel flowed out of the cannister so slow that we had to dump the contents out as it wouldn't drain. Nuff description I hope
The FASS uses approx. 3/4 inch id pipe to pick up fuel in the tank where it is sucked through a 10 micron filter (or less) on the fass assembly. It then filters out the "micro bubbles of air" that are only visible under magnification but that get entrapped in the diesel by being pumped back into the tank with air and constant sloshing of the fuel.
Long and Short of it is I've gone from less than 24 psi boost and mild EGT's to 34 psi (39 peak psi) mild Hot EGT's and a ton more power.
My mileage on the overhead is back to being accurate also, but unfortunately it is lower empty but better towing you win some you lose some.
09-27-2005, 01:16 AM
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"I have yet to see a fuel tank that didn't accumulate a layer of crud in it when the tank was not bottom outlet. When you checked your tank was the tank and the pick up clean? Does diesel float on water?"
Water goes to the bottom of the tank. It also mixes with diesel when the vehicle is in motion. If you have that much water in your tank, your water in fuel light must be constantly going off.
Water goes to the bottom of the tank. It also mixes with diesel when the vehicle is in motion. If you have that much water in your tank, your water in fuel light must be constantly going off.
09-27-2005, 11:11 PM
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I've been informed that some of the Dodge trucks have been fitted with defective tanks from the factory that aren't totally sealed and allow debris into them. I guess this might explain some of the crud and lift pump problems people are experiencing too.
I've had my '99 SD since it as new. Jan 2, 1999 to be exact. I dropped the tank last winter after getting a tank of gasoline at a service station. (Instead of diesel...) My tank was clean. I actually regretted dropping it.
I've had my '99 SD since it as new. Jan 2, 1999 to be exact. I dropped the tank last winter after getting a tank of gasoline at a service station. (Instead of diesel...) My tank was clean. I actually regretted dropping it.
09-27-2005, 11:52 PM
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Well my dealer phoned today to say the truck was running again, and a couple more little things to be fixed and I can pick it up tomorrow; huge surprise, it needed a lift pump (duh). The advisor said it also got the retrofit kit to place another pump in the tank (like the 05's apparently). He said the truck ran fine and had 25 psi at the head. Here's my question to anyone who may know... The advisor said the lift pump at the head was REMOVED, and now the only pumps on the truck are the new one in the tank and the holley blue pump I installed on the frame, the holley only puts out approx 15 psi, so if the head pump was removed, how can the pressure be 25psi? My common sense tells me the advisor may not know what he's talking about or doesn't have his facts straight. Does anyone know if this retrofit includes removing the head mounted pump?, I'll check tomorrow when I pick it up, but I'm not sure what to look for. If I can I'll try to talk to the foreman as well and get as many facts as I can. Any opinions on whether or not I should leave the holley pump on the frame? It doesn't seem to serve a purpose anymore now that there is a pump in the tank. Any feed back would be appreciated.