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Old 07-01-2015, 08:31 AM   #15
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Originally Posted by Ray,IN View Post
If my memory serves me, the lift pump has a return to the fuel tank(those 2 rubber lines). This is utilized when the injector pump cannot use it as fast as the lift pump supplies. I wonder if the lift pump fails internally, the manual fuel pump you used(fuel going somewhere) was pumping fuel into the return line?
A lift pump rebuild kit was available for my 1996 Dodge CTD (5.9)
For mine the fuel return is after the VP44. From quickserve service manual.
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Old 07-01-2015, 08:47 AM   #16
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Originally Posted by Sgt. View Post
tons of misinformation on the internet, no one will commit to the proper psi after lift pump, I have seen everything from as low as 9 to as high as 20. I'm at 14-12psi range from idle to heavy throttle.
Ok, the service manual on cummins.quickserve commits itself for my engine.

The outlet side of the fuel filter should be 10 psi minimum at high idle. The maximum drop allowed across the filter is 5 psi. On top of the filter there are two 1/8 npt plugs for measuring this pressure, both inlet and outlet

Glad you brought this up. I installed the my monitoring sensor on the inlet side so I guess I will change it to the outlet side since this is a more critical reading.

You can buy aftermarket pumps that deliver more than the stock pump 15 psi. May get one.
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Old 07-01-2015, 07:43 PM   #17
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Thanks to all for the help. I have done a lot of checking connections including suction and return on top of fuel tank, yup dropped it down enough to work on it. I have found a small fuel leak on the side of the fuel filter, it looks as though an o ring may be in need of replacement. This leak is on the lever that is used to drain off any water in this filter housing. I am going to install a pressure gauge with the scrubber (sending unit) coming off the bottom of this housing, so am waiting for parts and then well repair lever at the same time. Am hoping that this leak is my problem but it is looking more and more like a new injector. Well post after repairs. Finger crossed.
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Old 07-01-2015, 08:48 PM   #18
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GPM

[QUOTE=Skip426;2628543]Test info from Cummins on the Dodge/Cummins electric lift pump on the 24 valve engine , was always GPM , not PSI.[/QUOTE


Not really sure what your point is, do you have the so called Dodge/Cummings GPM data? Could you please share it? Several post speak or dodge not willing to commit to anything because they would admit fault in there obvious week leak lift pump.
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Old 07-01-2015, 09:31 PM   #19
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Sgt. You would have to go back and check out previous threads to see what my point was. I installed a new lift pump that is working fine. There are two things that have to be checked when determining if you need a new lift pump not just rpm but also psi, i have done a volume test and now want to know the real time psi of the fuel being supplied to the vp44 under load.
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Old 07-02-2015, 08:24 AM   #20
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Quote:
Originally Posted by Salmon Run View Post
Thanks to all for the help. I have done a lot of checking connections including suction and return on top of fuel tank, yup dropped it down enough to work on it. I have found a small fuel leak on the side of the fuel filter, it looks as though an o ring may be in need of replacement. This leak is on the lever that is used to drain off any water in this filter housing. I am going to install a pressure gauge with the scrubber (sending unit) coming off the bottom of this housing, so am waiting for parts and then well repair lever at the same time. Am hoping that this leak is my problem but it is looking more and more like a new injector. Well post after repairs. Finger crossed.
you sure don't want any leak on the suction side of the lift pump. It will suck air. Those O rings should seal completely. that leak could be causing the pump to entrainment of air to the v44. That would cause sporadic operation too. My fuel tank once suffered a vacuum due to a stuck overturn valve on the top of the tank and stuck fuel cap not venting the tank properly. this caused the v44 to suffer fuel loss and lack of lubrication. $4000
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Old 07-02-2015, 11:03 AM   #21
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[QUOTE=Sgt.;2629838]
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Originally Posted by Skip426 View Post
Test info from Cummins on the Dodge/Cummins electric lift pump on the 24 valve engine , was always GPM , not PSI.[/QUOTE


Not really sure what your point is, do you have the so called Dodge/Cummings GPM data? Could you please share it? Several post speak or dodge not willing to commit to anything because they would admit fault in there obvious week leak lift pump.
I'm 8 years retired , and can't remember the number. But remember running the tests many times. The shop scan tool allowed for the lift pump to be set to continuous run into a container. ( not just the 18secs. after key on) Then on reporting to Cummins , the test results, they would authorize the replacement.
I was always frustrated by the fact that the Cummins ECM, had many unused input/output channels , and could easily have been set up to monitor supply fuel pressure at the injector pump, and trigger a low fuel pressure warning , to inform the driver of a plugged fuel filter or failing lift pump.
The location of the pump always was a bone of contention too. Electric pumps , push better that they pull, don't like heat and vibration, so on the side of the engine X number of feet from the tank isn't an ideal location.
Lift pump issues continued; in Dodge anyway; even with the introduction of the HPCR fuel system in 2003. Then finally in 05 they moved the lift pump into the fuel tank and released change up kits for the previous year's 24 valve engines, to do the same.
If I'd put aside $5 for every , Cummins lift pump and VP-44 injector pump I replaced my last years before retirement , I could have retired at least a year sooner.
Here's a little memo I found on the injector pumps.
Attached Files
File Type: pdf BOSCH VP44 INJECTION PUMP FAILURES EXPLAINED.pdf (32.8 KB, 125 views)
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Old 07-02-2015, 12:27 PM   #22
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Skip,

Great info. I think I have seen it before but this time I stored it in my Cummins folder.

Maybe you can verify some of the internet stories. The one I am concerned about is as follows:

The VP44 has an internal mechanical pump that assist in fuel flow. When the lift pump has low pressure it strains the internal mech pump to the point of failure. So when my lift pump started going downhill I replaced it.

Also some of the after market pumps go much higher in pressure than the normal pump. Would it be worth it to install one of these pumps to make the VP44 last longer?? My engine performance is great with the stock pump.
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Old 07-02-2015, 02:09 PM   #23
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For mine the fuel return is after the VP44. From quickserve service manual.
Right, that one is an absolute necessity since the pump is a piston pump; the output has to go somewhere.
There are 2 hoses going to the lift pump on the rear drivers side of the block, one is supply, the other return.
The best solution is to install an electric(diesel) fuel pump just after the line leave the fuel tank. Otherwise the OEM lift pump has to suck fuel all the way from the tank. All excess fuel is returned to the tank at the lift pump, and all excess pressurized fuel is returned to the fuel system between lift pump and injector pump. It's been 16 years since I worked on my 5.9, but that's how I remember the fuel system.
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Old 07-02-2015, 06:21 PM   #24
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Thanks Ray.

Will be working on mine for a few years. Made a removable panel in the rear compartment so I have easy access to the Lift Pump. Gage sensor fuel filter/separator and the ECM. Oh my stock pump is electric.
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Old 07-02-2015, 07:34 PM   #25
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Originally Posted by greystroke View Post
The VP44 has an internal mechanical pump that assist in fuel flow. When the lift pump has low pressure it strains the internal mech pump to the point of failure. So when my lift pump started going downhill I replaced it.

Also some of the after market pumps go much higher in pressure than the normal pump. Would it be worth it to install one of these pumps to make the VP44 last longer?? My engine performance is great with the stock pump.
I , can't confirm any internal mechanical lift pump in the VP-44, I do know that if the lift pump failed while the vehicle was in motion the engine would sometimes continue running at reduced power for a short period of time, due to a slight vacuum produced by the high pressure portion of the pump , but that high pressure portion would soon overheat and fail.
Unlike the CAPS fuel system on larger Cummins of the era, the VP-44 required the lift pump run continually to survive.
The VP-44 at max output only uses 30% of the fuel that it's supplied by the lift pump, the other 70% is used for lubrication and cooling and returned to the tank.
I don't know if it would be possible to over-pressurize the inlet side of the VP-44, but JMHO anything over 10 PSI , would be over-kill. As the Cummins techs and testing suggested, volume over pressure.
But how much volume of fuel can you push through a fuel line, without building pressure?
Like I said in the previous post , location of the Cummins installed lift pump was, in my opinion, it's main fault, if you do install anything after market , I'd be placing it as close to the fuel tank as possible.
The Dodge/ Cummins ECM, would monitor the lift pump, power consumption and set a code based on that power use; lift pump volts high/low.
BUT!!!!!
Because the lift pump failing was not considered an emissions related fault the ECM would not turn on the CEL.
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Old 07-02-2015, 08:13 PM   #26
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Thanks skip, so I will stay with stock pumps.
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Old 08-26-2015, 08:52 AM   #27
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I have a 2003 XC chassis with the Cummins ISB 300 HP. Where is the lift pump located. I have chased fuel lines behind wiring and hoses and cannot put my hands on my lift pump.
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Old 08-26-2015, 10:03 AM   #28
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I have a 2003 XC chassis with the Cummins ISB 300 HP. Where is the lift pump located. I have chased fuel lines behind wiring and hoses and cannot put my hands on my lift pump.
Why do that? I suggest you get a free sign in to Quickserve.cummins.com where you will have access to all parts and maintenance manuals for your engine by your Engine SN. For example, my engine is much older so you can't use my info but I post this from one of my maintenance manuals. Tells the whole story.
Attached Thumbnails
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Name:	Engine Fuel Diagram.jpg
Views:	15151
Size:	91.9 KB
ID:	104752  
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