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Engine/Transmission (1998.5 - 2002) Follow up to lift pump survey
- Thread starter FDNYMOPARGUY
- Start Date
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99/3500/4x4/SLT QC/5spd (5th gear failed at 80,000)/86,000/van akien box, lager injectors, mangnaflow/ no lift pump failure 
01/2500/4x4/SLT QC/AT/89,000/no mods other than transmission box for lock up/also no lift pump failure
99/3500/4x4/SLT QC/5spd/84,000/van akien box,straight pipe/ no lift pump failure
01/2500/4x4/SLT QC/AT/89,000/no mods other than transmission box for lock up/also no lift pump failure
99/3500/4x4/SLT QC/5spd/84,000/van akien box,straight pipe/ no lift pump failure
1999 / 80,000/Quad cab long bed/Geno's Banjos/no failures (yet)/14psi idle, 12psi load, 10psi WOT.
survey
2001/ 2500 QC LB/ no mods / 85,000 replaced 9idle,7load, wot not tested/ new pump 14. 5idle, 13 load, 10 wot
2001/ 2500 QC LB/ no mods / 85,000 replaced 9idle,7load, wot not tested/ new pump 14. 5idle, 13 load, 10 wot
2oo2-2500-QC-SB-Comp-39,000 miles no problems-11 idle 2 @ WOT 5x5- Comp on for 5,000 miles,- Updateing to EEp demon Fueling kit In near future.
2001 QCSB 6sp HO. 1 failure at 165000km. Not sure what my pressures are have no gauge. Truck is all stock. So far. Have trouble starting when it gets cold -20 C. replaced one pump myself last winter and had the same symptoms for a while then they dissappeared until this winter. Has anyone out there tried using an air/fuel seperator on their truck and has this made any difference?
MWeagley:
Fuel pressure is used as an indicator of flow and one of the reasons we use fuel pressure gauges is a simple matter of economics: Flow gauges could be installed, but they are extremely expensive.
One thing to remember is that pressure and flow work somewhat hand in hand. If you have a fixed outlet size, and you increase the flow rate, the pressure will also increase. Positive pressure is a sign of flow and that the lift pump is pushing fuel through the filter to the injection pump as required by the VP44.
There is a second reason that we measure pressure instead of flow: it is possible to have flow and no pressure, such as when the lift pump fails and the injection pump pulls the fuel to it. You would still have flow, but zero pressure in the line between the lift pump and the injection pump. (Technically, it would be a negative pressure, or vacuum, not zero). The engine still runs, but the injection pump is being somewhat starved for fuel. Experience has taught us that this condition is destructive to the innards of the VP44 injection pump.
It is also possible for a pump to begin to fail, such that it will move fuel at low pressure, but is incapable of moving fuel at an elevated pressure, even if that pressure is slight. DC engineers (possibly along with Cummins) have realized that if they test a marginal pump under the correct conditions, there is a greater possibility that it will pass the test, meaning they replace fewer of them under warranty. An open flow test where fuel flow is being measured from an open line is NOT a real world test, as the line is never fully open when the engine is running. A marginal pump may pass this test, but it's days are numbered at that point, and replacement will be imminent in the near future.
The open line flow test (for warranty matters) is simply a method of getting the monkey off their back for a short time. DC knows that if they test a pump with the flow test, and it passes, that you will have no choice but to go your merry way, and with a little luck, your truck will be out of warranty before you come back complaining of the same problem, meaning you foot the bill instead of DC. The reality of it is that continuing to run the vehicle with this condition exposes the VP44 to increased risk of major damage. :{
I'll bet a $10 bill that if your truck is out of warranty, and you take it in with zero fuel pressure, your friendly Dodge mechanic will first test with his pressure gauge, and then say "Yup, you need a new lift pump" without even doing the flow test. This is because they know that the pump is going through it's death throes at that point, and John A. Customer is paying the bill instead of DC. #@$%!
Fuel pressure is used as an indicator of flow and one of the reasons we use fuel pressure gauges is a simple matter of economics: Flow gauges could be installed, but they are extremely expensive.
One thing to remember is that pressure and flow work somewhat hand in hand. If you have a fixed outlet size, and you increase the flow rate, the pressure will also increase. Positive pressure is a sign of flow and that the lift pump is pushing fuel through the filter to the injection pump as required by the VP44.
There is a second reason that we measure pressure instead of flow: it is possible to have flow and no pressure, such as when the lift pump fails and the injection pump pulls the fuel to it. You would still have flow, but zero pressure in the line between the lift pump and the injection pump. (Technically, it would be a negative pressure, or vacuum, not zero). The engine still runs, but the injection pump is being somewhat starved for fuel. Experience has taught us that this condition is destructive to the innards of the VP44 injection pump.
It is also possible for a pump to begin to fail, such that it will move fuel at low pressure, but is incapable of moving fuel at an elevated pressure, even if that pressure is slight. DC engineers (possibly along with Cummins) have realized that if they test a marginal pump under the correct conditions, there is a greater possibility that it will pass the test, meaning they replace fewer of them under warranty. An open flow test where fuel flow is being measured from an open line is NOT a real world test, as the line is never fully open when the engine is running. A marginal pump may pass this test, but it's days are numbered at that point, and replacement will be imminent in the near future.
The open line flow test (for warranty matters) is simply a method of getting the monkey off their back for a short time. DC knows that if they test a pump with the flow test, and it passes, that you will have no choice but to go your merry way, and with a little luck, your truck will be out of warranty before you come back complaining of the same problem, meaning you foot the bill instead of DC. The reality of it is that continuing to run the vehicle with this condition exposes the VP44 to increased risk of major damage. :{
I'll bet a $10 bill that if your truck is out of warranty, and you take it in with zero fuel pressure, your friendly Dodge mechanic will first test with his pressure gauge, and then say "Yup, you need a new lift pump" without even doing the flow test. This is because they know that the pump is going through it's death throes at that point, and John A. Customer is paying the bill instead of DC. #@$%!
Last edited:
01. 5, Quad/long/stock truck... 1st lift pump failure at 96k. Currently 96. 5k on truck.
uk truck low on power, 4 days of reading tdr made up preasure guage to test yeh right 5-7 psi at idle 2-3, when reving,gotta change the pump, question is how long a job is it, like most i thought these trucks were bullet proof, after having land rovers ,toyotas, etc ,why havn,t dodge sorted this prob,???,
2/25/05 Lift pump goin south. Just installed westach guage and pressure is not lookin good. 10idle 3to4 cruise 0 WOT. Got a spare ill be puttin on. Im goin to oreder a pump from summit racing to mount on the frame to replace stock pump. THey have real good price. '02 long box quad cab all stock except for AFE and 4" straight exhaust. Much more bombs to come WOOOOHOOOOOOOOOO!!!!!
"did factory locktite the mount bolts?"
They sure did on my '02 - and a real BEAR to get off, too!
PLUS, the thread locker tends to cause the whole bolt to start turning down in the pump section instead of the mounting nut coming off - and THAT'S sure lotsa fun!
:{
Imagine fighting THAT out on the road in the dark and rain!
"01/60250/Quad-Long-4x4/no Bomb/1 failed@60100/no guages (yet)"
Now THERE'S a fella who loves to live dangerously - even after *one* LP has already failed on him!
They sure did on my '02 - and a real BEAR to get off, too!
PLUS, the thread locker tends to cause the whole bolt to start turning down in the pump section instead of the mounting nut coming off - and THAT'S sure lotsa fun!
:{ Imagine fighting THAT out on the road in the dark and rain!
"01/60250/Quad-Long-4x4/no Bomb/1 failed@60100/no guages (yet)"
Now THERE'S a fella who loves to live dangerously - even after *one* LP has already failed on him!
2001. 5 Replaced at 62000 miles 2-4 # at idle 0 at open. No engine mods.
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Issue 128 – Digital Version
Digital Magazines
FREE!
TDR Test Drive - Digital Edition
Renew
Subscribe
Gift Subscriptions
Back Issues
Subscription Status
Address Change Form
Buyer's Guides
Ram Diagnostic Trouble Codes
The Perfect Collection
The Perfect Collection Vol. II
TSB Updates
Dodge/Cummins Historical Overview
Cameron Collection
What Makes Us Tick?
Product Showcase
Advertising
