Could someone please explain to me the symptoms of lift pump failure? I do not have fuel gauges, so would appreciate performance factors. Does lack of the short run time after bumping the starter mean failure?
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What are Symptoms of Lift Pump Failure?
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My first clue was a real bad stumble after a short but hard run with the EZ on a cold November morning. The truck lost all power and began to emit clouds of white. I pulled over, let it idle for a minute, then took off with no further symptoms. I didn't have a FP gauge at the time, just an idea of low psi's from reading on the TDR.
Shortly there after, took the truck to Auto Wurks for some BOMBing, asked them to check the FP and found that I had around 4 psi's at idle and 0 at WOT.
Do yourself and your truck a favor, check those psi's, even if it is only at idle with a temporary gauge. If you have a FP gauge installed, you will probably see sporadic highs and low that are not within the norm of your typical FP readings. Once you start seeing these out of norm numbers, be prepared to replace the lift pump sometime soon, as it is more than likely on the way out. I believe that this should be mandatory before you BOMB with larger injectors, fueling boxes, etc. , as you will be taxing the weak link with a larger demand that it may not be able to provide.
If you can only test at idle psi's with a temporary gauge, I have found, with the heavy fueling mods. that I have in my truck, that a reading of 12 psi's post filter or 13 psi's prefilter ( I have two FP gauges), is more than enough to keep up with my fueling demands. Note that I am not using the Carter pump or in bound banjo bolts anymore, I have a Mallory 4150 located back by the tank and all lines are the braided SS with Aeroquip elbows.
If you bump your starter, you should hear the lift pump operating for about 25 seconds or so. If you just key on the ignition, the pump only runs for about 3 seconds.
Hope this helps !!!!
Scott W.
Shortly there after, took the truck to Auto Wurks for some BOMBing, asked them to check the FP and found that I had around 4 psi's at idle and 0 at WOT.
Do yourself and your truck a favor, check those psi's, even if it is only at idle with a temporary gauge. If you have a FP gauge installed, you will probably see sporadic highs and low that are not within the norm of your typical FP readings. Once you start seeing these out of norm numbers, be prepared to replace the lift pump sometime soon, as it is more than likely on the way out. I believe that this should be mandatory before you BOMB with larger injectors, fueling boxes, etc. , as you will be taxing the weak link with a larger demand that it may not be able to provide.
If you can only test at idle psi's with a temporary gauge, I have found, with the heavy fueling mods. that I have in my truck, that a reading of 12 psi's post filter or 13 psi's prefilter ( I have two FP gauges), is more than enough to keep up with my fueling demands. Note that I am not using the Carter pump or in bound banjo bolts anymore, I have a Mallory 4150 located back by the tank and all lines are the braided SS with Aeroquip elbows.
If you bump your starter, you should hear the lift pump operating for about 25 seconds or so. If you just key on the ignition, the pump only runs for about 3 seconds.
Hope this helps !!!!
Scott W.
dealer says mine is covered under warranty
Coming back from a biking adventure (to Monte Cristo, WA) last weekend, I noticed a stumble in my engine whenever I was over 1800 RPMs and under load (any speed, any gear). Thought maybe it was a clogged air filter from the Mountain Highway Loop (~15 miles of dusty dirt road) but it was fairly clean. Thought maybe it was a bad load of fuel so I changed the fuel filter (~8000 on the old one) and while it was pretty dirty, I don't think it was enough to prevent fuel flow. So that left me at the lift pump. I don't have any guages installed, so I'm not positive, but from what I've read here, my suspicion is pretty strong. I have 55K on my truck.
Called my dealer (Frontier Dodge in Burlington, WA), explained the situation and asked if the lift pump was covered under the 5/100 Cummins warranty. She said, "yep, sure is. " So I dropped it off tonight. So far, so good. I'll let you know how it goes, but these guys have been pretty good as far as I'm concerned so far. I told her I suspected either fuel pump and that I had just replaced the filter to be sure. They'll test it tomorrow and let me know. She also told me about the hood latch recall that I had totally forgotten about.
Coming back from a biking adventure (to Monte Cristo, WA) last weekend, I noticed a stumble in my engine whenever I was over 1800 RPMs and under load (any speed, any gear). Thought maybe it was a clogged air filter from the Mountain Highway Loop (~15 miles of dusty dirt road) but it was fairly clean. Thought maybe it was a bad load of fuel so I changed the fuel filter (~8000 on the old one) and while it was pretty dirty, I don't think it was enough to prevent fuel flow. So that left me at the lift pump. I don't have any guages installed, so I'm not positive, but from what I've read here, my suspicion is pretty strong. I have 55K on my truck.
Called my dealer (Frontier Dodge in Burlington, WA), explained the situation and asked if the lift pump was covered under the 5/100 Cummins warranty. She said, "yep, sure is. " So I dropped it off tonight. So far, so good. I'll let you know how it goes, but these guys have been pretty good as far as I'm concerned so far. I told her I suspected either fuel pump and that I had just replaced the filter to be sure. They'll test it tomorrow and let me know. She also told me about the hood latch recall that I had totally forgotten about.
Re: dealer says mine is covered under warranty
Year? mod 25-3500 2x4 -4x4? LOL Ron in Louisville ky
Hmmm, that's kinda of strange, Joel. I thought that, when the VP44 goes, it just goes, no real symptoms before it's death ???? It would be interesting to hook up a FP gauge and take a long ride in your truck, wondering if the telltale signs of a lift pump going bad are present. Any of the pro's care to comment ??? Is it true that they, the DC techs, can test the psi's without the truck under a load to establish whether a lift pump isn't performing when they troubleshoot same. I believe that I read that here. Just curious. If your pump is only giving 8. 5 psi's at 35 MPH, still don't sound good to me.
Scott W.
Scott W.
I'm definately going to keep an eye on it!
I do need to get a guage hooked up to the lift pump to see what it's doing. Maybe after they put in the new injection pump it'll still do the same thing and I'll get both!
I can't say about how it fails. Like I said, I had stumbling and max speed of about 50 in 4th, 55-60 in 5th; any more would bring on the stumbling and shuddering. It happened on Saturday on the way home. Sunday I changed out the fuel filter (thought maybe a bad batch of fuel) but that didn't help at all. It also took me at least 15 starter bumps to finally get the engine started. Loosened a test fitting on the filter and it was full, so I finally just ran the starter for probably longer than I should have and it finally fired. I guess that sounds like the injection pump isnt' putting out what it should. The lift pump dutifully ran for 20 seconds or so every time I bumped the starter.
I do trust these guys, they've been pretty straight with me so far. I'd have no hesitation whatsoever about recommending any of you in WA to go there for service and/or to buy a truck, so when they tell me the lift pump is good (at least within their specs) I take them at their word. I will watch it however, because when it does fail... .
On another note, my truck won't be ready 'till Friday because they can't order this part directly from their warehouse. They have to get it from DC and can't order it without turning in the part number of the failed unit. You suppose they're watching the failure rate of these things? Of course, they'd never do a recall for them, even if every 98. 5-99 pump has to be replaced eventually. Better to not quibble about the warranty replacement than recall the stupid things, I guess.
I do need to get a guage hooked up to the lift pump to see what it's doing. Maybe after they put in the new injection pump it'll still do the same thing and I'll get both!
I can't say about how it fails. Like I said, I had stumbling and max speed of about 50 in 4th, 55-60 in 5th; any more would bring on the stumbling and shuddering. It happened on Saturday on the way home. Sunday I changed out the fuel filter (thought maybe a bad batch of fuel) but that didn't help at all. It also took me at least 15 starter bumps to finally get the engine started. Loosened a test fitting on the filter and it was full, so I finally just ran the starter for probably longer than I should have and it finally fired. I guess that sounds like the injection pump isnt' putting out what it should. The lift pump dutifully ran for 20 seconds or so every time I bumped the starter.
I do trust these guys, they've been pretty straight with me so far. I'd have no hesitation whatsoever about recommending any of you in WA to go there for service and/or to buy a truck, so when they tell me the lift pump is good (at least within their specs) I take them at their word. I will watch it however, because when it does fail... .
On another note, my truck won't be ready 'till Friday because they can't order this part directly from their warehouse. They have to get it from DC and can't order it without turning in the part number of the failed unit. You suppose they're watching the failure rate of these things? Of course, they'd never do a recall for them, even if every 98. 5-99 pump has to be replaced eventually. Better to not quibble about the warranty replacement than recall the stupid things, I guess.
I purchased one of the 0-15psi 1. 5" VDO Mini FP gauges from egauges.com for $25. 50 and screwed it directly to the fuel filter housing on my 99. At idle, am seeing 11. 5-12 psi at the fuel filter input test port. Engine vibration makes the pointer wiggle pretty good, but it still provides a quick/easy indication of the lift pump's health.
Edited: 8/22/2001
This evening, I remoted my little VDO gauge so I could see what's happening under load. Here's what I read:
Idle = 12 psi
Normal Cruising = 9 -10 psi
WOT Climbing a hill = 5 psi
Lift pump is original & truck has ~40k Miles on it. I have replaced the OEM Banjo fuel lines with a set of 3/8" braided ss fuel lines, which probably lowered pressures a little.
At least the FP is not dropping to Zero (0) at WOT
Think I will order a pump, just to have around in case...
FDz
Edited: 8/22/2001
This evening, I remoted my little VDO gauge so I could see what's happening under load. Here's what I read:
Idle = 12 psi
Normal Cruising = 9 -10 psi
WOT Climbing a hill = 5 psi
Lift pump is original & truck has ~40k Miles on it. I have replaced the OEM Banjo fuel lines with a set of 3/8" braided ss fuel lines, which probably lowered pressures a little.
At least the FP is not dropping to Zero (0) at WOT
Think I will order a pump, just to have around in case...
FDz
Last edited:
threee seconds...
Bigsaint,
Three seconds is too long for the lift pump to run to prime on the IGN spot. I good lift pump will run only a third to a half second. If the pump runs longer, then there must be a check ball problem or weak pump. I just had to replace mine, and the new pump runs for the short time listed above. My old lift pump ran longer and longer as it got miles on it. Finally went out at 42k miles.
I think the three seconds is the max the pump can run on the relay. If it runs that long, than I think there is a problem.
Bigsaint,
Three seconds is too long for the lift pump to run to prime on the IGN spot. I good lift pump will run only a third to a half second. If the pump runs longer, then there must be a check ball problem or weak pump. I just had to replace mine, and the new pump runs for the short time listed above. My old lift pump ran longer and longer as it got miles on it. Finally went out at 42k miles.
I think the three seconds is the max the pump can run on the relay. If it runs that long, than I think there is a problem.
help for the fans
There has been lots of threads on this subject. I see a new one about every day. The TDR is here to help, nobody knows it all Bigsaint, and neither do I.
We all are here to have fun with our toys, and get them fixed when they break.
I am going to install a pumper pump to fed the stock lift pump, and hopefully prevent any more failures. Ohh, and install some gauges soon so I can keep a tab on unpleasant surprises.
There has been lots of threads on this subject. I see a new one about every day. The TDR is here to help, nobody knows it all Bigsaint, and neither do I.
We all are here to have fun with our toys, and get them fixed when they break. I am going to install a pumper pump to fed the stock lift pump, and hopefully prevent any more failures. Ohh, and install some gauges soon so I can keep a tab on unpleasant surprises.
Nat, what interested me was the idea that some pumps would run for a shorter time than others, I thought that any pump connected to the line from the ECM, regardless of whether a relay was used, as mine is with the Mallory, would receive a short power burst, if you will, and run until the ECM cuts the power. Still learning here, hope that never ends 
. Please don't take what I said as an attempt to flame, not intented.
Scott W.
. Please don't take what I said as an attempt to flame, not intented. Scott W.
pumps
I believe the pump's running time is controlled by the ECM, but I am not sure. I do know that the power wire does come through the ECM to the pump. I guess you would have to be an D-C engineer to answer how long it should run.
Bigsaint, you are a big help to the folks here. I would not flame anyone else either, nor do I think you were flaming me. I find this site fascinating, and have learned lots by it.
Anyone else have an answer on how long the stock lift pump should run???
I believe the pump's running time is controlled by the ECM, but I am not sure. I do know that the power wire does come through the ECM to the pump. I guess you would have to be an D-C engineer to answer how long it should run.
Bigsaint, you are a big help to the folks here. I would not flame anyone else either, nor do I think you were flaming me. I find this site fascinating, and have learned lots by it.
Anyone else have an answer on how long the stock lift pump should run???
with all the failures, obviously not long enough. But seriously, my truck will run the pump at different inverval. The reason I say that is that it is pressure determined how long the pump should run, thus if the truck has sat longer, the pump will run longer on the initial prime, but the pump could not run at all if just shut down. These are my observations of the running of the lift pump.
PS. I have my mallory running straight off the same wire the stock one did.
Morph.
Morph, I also wondered if the run time was pressure controlled, which kind of gets back to the original question that started this thread. However, I could find no mention in the Service Manual of pressure control, but that is sure how mine seems to act also. (Note: I inadvertently hit the wrong button and also posted this to a new thresd... oops)
lift pump symptoms
I posted last week and earlier about lift pump. From the guys here I found out what took the dealer 4 months. They replaced my pump last week they said they pump was running intermitantly when starting I first noticed a stumple every once in a while between shifting gears and alot of white smoke with it it would stop if you let off the the throtle. Posted end of July early aug. if you interested. I noticed the new pump runs I'm guessing 2-3 seconds when you turn the key. Not sure how to post my topics with this. It took the guys here one post to fix my problem! In my last post I included the new part number and I'm pretty sure someone else did.
I posted last week and earlier about lift pump. From the guys here I found out what took the dealer 4 months. They replaced my pump last week they said they pump was running intermitantly when starting I first noticed a stumple every once in a while between shifting gears and alot of white smoke with it it would stop if you let off the the throtle. Posted end of July early aug. if you interested. I noticed the new pump runs I'm guessing 2-3 seconds when you turn the key. Not sure how to post my topics with this. It took the guys here one post to fix my problem! In my last post I included the new part number and I'm pretty sure someone else did.
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