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Discussion Starter #1
OK, a few months back I replaced my lift pump because the truck would occasionally sputter or miss at idle and only 1 or 2 times it stumbled when pulling out from a stop. The pump was still working but I could not hear it when I cycled the key so I just replaced it. I also installed a fuel pressure light, comes on at under 5psi, and replaced the filter becuase the light would flutter when I would get above 1000RPM. That filter worked, no low pressure light, for about 20 miles before the light started to flutter again. The light mfg stated that the light coming on was normal for a stock motor & lift pump so I lived with it. In the past 2 weeks the sputtering has gotten worse and even stalled on me. I will sit at idle and stare at the pressure light and it does not flutter when the engine stumbles. I have talked to 2 mechanics and one is saying water in the fuel being pushed through the filter and the other is saying algea. I replaced the fuel filter on Sat and the light was out for about 3 miles before it started fluttering again. Monday morning it sputtered and stalled on me in the driveway and then ran like a champ the rest of the day.

Today I stopped and got PS Biocide, I do use PS with every fill up, and was told by the parts guy to use dry gas becuase it sounds like water to him. He has some that says it is for diesel but it still contains alcohol and I was always told to never use that in a deisel engine. He claims that the truckers swear by it.

Everything seems to have gone down hill for me since the ULSD change over.

With everything that I've read on here I have a injection pump going bad to an air leak in the system. I don't think it's an air leak becuase I can click the key for the heater and the pressure will hold above 5psi for about 8-10 seconds after the pump stops running.

I really don't wish this problem on anyone but I'm hoping someone else has had this issue and can help me out. At this point I'm about to drive it off a cliff.

Sorry this was so long but I'm really at a loss with this. Any help that anyone can provide would be greatly appericiated. Thanks in advance.
 

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have you checked for codes using the key trick?
 

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Discussion Starter #3
Code

The only code that shows up is P1693 which has been there for as long as I can remember.
 

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I had the same problem and changed the injection pump the problem went away.
joe
 

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Find a scan tool or take it to Autozone and scan it. I'd suspect a problem in the VP44 control circuit or computers. ARe you getting the dead pedal?

Ops
 

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Discussion Starter #6
No dead pedal. Just very random. Truck has good power. No RPM drop or slow down on hills. Just the stumble. It did it to me again this morning. Once pulling up to a stop sign and again just after I pulled out. I did notice that after it stumbled when I pulled out that the fuel pressure light when out for a few hundred feet. I really don't want to have to replace the injection pump. Could it be that I just have water being pushed through the filter as one mechanic suggested?

Thanks
 

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I had the same problem and changed the injection pump the problem went away.
joe
i agree when ever the lift pump goes out likke that the injector pump goes out right after so i would have to say its thet same thing
 

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I tried a lift pump and it helped for about a day. When it would be idleing it would cough and come right back. No loss of power no dead pedal.
Joe
 

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Discussion Starter #10
Thanks for the help guys. Not what I wanted to hear but I guess that is the way it goes. Although it ran like a champ until this morning. It stumbled 3 times on the way to work. I will just run it until it stops and then replace the VP.

Thanks Again.
 

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Discussion Starter #11
One more question. Would a dieing VP cause low fuel pressure? The reason I ask is that after this morning when it stumbled my fuel pressure light is coming on at about 800RPM and stays on pretty solid. Very little flutter like before but no stumbles. I'm going to replace the fuel filter again tomorrow becuase whenever I do I don't see the light for a few miles anyway. Oh, and the light now comes on as soon as the lift pump stops when I'm waiting for the "Wait to start" light to go out and we are talking a second between the one light going out and the other coming on. Any one had that issue or am I still looking at replacing the VP.

Sorry to be a pain but the Dodge dealers around here like to make guesses until they stumble on the real issue and at $85/hr they are my very last resort.

Thanks again guys.
 

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I would say the new lift pump is junk. Have seen that as well.
 

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I had an 02 that had the exact same problem, seemed like it was worse in the summer than in the winter. Never had a problem with my foot on the pedal, but it had a hell of a time idling. I had a holly blue on it and I could never afford to put something else on. A few guys on here suggested pulling out and cleaning two sensors that are on the intake manifold. I forget which ones ask around somebody will know. Never fixed mine, but I hope it helps you.
 

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I went through 3 OEM lift pumps in less than a year on my 98 before I put the FASS on it. One lasted less than a week. I have a fuel pressure gauge so I can tell more what is happening than a light could tell me.

The motors in all of the OEM pumps I had (4 including the original) still ran but the pumps failed to pump. One of them sucked the spring of the internal bypass regulator through the pump and I found most of it in small pieces at the bottom of the filter housing.

I'd put a good lift pump on it (Like an AirDog or FASS. If I had it to do over I think I'd try an AirDog.), clear the codes, and hope the VP is OK. The longer you wait the more likely you will kill the VP, if it is not already in trouble.

Even if a good lift pump does not solve your current problem, you need one.

I have had the FASS on my 98 for over three years since my OEM pump trouble and have 123K miles on the original VP.
 

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Discussion Starter #16
Thanks for all the input guys. I replaced the fuel filter over a week ago and got about 25 miles before the light started to flutter again. It has not stumbled, knock on wood, since. I don't have any white smoke issues.. Nice puff of black smoke at startup. After reading some other things in this 911 forum I'm thinking I might have to breakdown and go to the dealer to have them check the ECM. I didn't know that the LP ran at different levels. That may expalin why the light goes out if I really lay into the peddle but comes on with a light touch.

Thanks agian for all the input by everyone.
 

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Discussion Starter #17
UPDATE - Took the truck in last week to have it looked at. They had if for 3 days and could not find the problem. It stumbled once for them in the shop but they were getting ready to do a road test and had just fired it up and walked away ad didn't have anything hooked up to it. The put 60 miles on it over 2 days and nothing. The only thing they found was that my wastegate is stuck closed so I had an overboost code but they said that would not cause the issue. It also had a code where the pump lost connection to the main computer but they cleared that before the stumble and it did not come back after the stumble. My fuel pressure was 16-18psi post filter an 12-14 after filter. They lowest they could get it to drop was 8psi at WOT. They did tell me that my pressure light was coming on even though my pressure was fine. Now I need to get a gauge for my own piece of mind. All they could tell me was "Bring it back if it gets worse and we will look at it some more" The good thing was that since they could not find the problem they only charged me for 2hrs labor. They also tested the fuel and everything is fine there. No water like I was thinking.
It did run fine until this morning. It had one small stumble in the driveway but ran like a champ the entire way to work.
 

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What kind of sender do you have to the low pressure light? If you just got one from Napa then it was most likely not rated for Diesel. I went to the local Frieghtliner Dealer for mine... about $13. I ran a T and feed the idiot light and guage right off of the VP. The only time I see the light is between the time I turn the key and when the wait to start light goes out.
As for the stumble, if you have a good lift pump, then it is most likely in the VP-44. I installed an Air Dog 100gph pump and I love it because of the built in regulator. I get a constant 14.5 psi throughout the rpm range no matter what the load. No more hicups/dead spots/hesitations. Good Luck... Chris
 

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Discussion Starter #19
The sensor and light were a complete kit from BD Diesel. The stumble is back now in full force. It did it twice this morning while driving down the road at about 800RPM. I hate to say it but at this point with the price of diesel, $4.55, and a problem that the dealer cannot find it might be time to go back to a gasser.
 
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