Engine/Transmission (1994 - 1998) Fuel contamination or lift pump?

[Jfam]

Problem Persists

I knew when the outside temperature rose above 80 that the real test was at hand. Unfortunately, after driving 30 miles and then stopping for 15 minutes, I learned that I had not solved the problem.



The truck (94 226k) started hard. After 1/8 mile it hung at 30 miles per hour for about 50’ then stalled. The hanging and resistance on the accelerator pedal is a real mystery to me. Repeated attempts to restart always got it stared, but it would always stall. Fuel pressure dropped, of course. And the ticking would intermittently reappear.



I got out and had my wife restart while I put my hand on the fuel shut-off solenoid plunger. It was and remained all the way up as I applied throttle and she stalled. I had some fuel on my hand when I retracted it.



After about 15 minutes of this, she started and ran fine. Ran the 30 miles to work this morning fine too.



Fixes so far: Replaced supply and return fuel hoses. New lift pump. New overflow valve. What’s left!!!???? I'm thinking that fuel shut off solenoid is the most likely candidate, though the tech at the dealer said try the relay first as that was his experience with one other vehicle. It seems to be to be a fuel delivery problem, though I suppose it could just as easily be a large air leak somewhere. Could the solenoid assembly be sucking air when hot?



Any advice appreciated….

 

[illflem]

No fuel flows though the shut down solenoid, it's just a mechanical linkage. Have no idea where the fuel on your hand came from except maybe some reside from bleeding.

Hate to say it but with all you have done already I'm leaning towards an injection pump problem, could be time for a rebuild. Piers has good deals on them with fast turn around, but you're still talking expensive.

 

[johnjackson]

Joe, If the fuel shutoff lever is staying up through all this it is probably not the solenoid or relay. You might try a search on P7100. There was a thread that sounded like similar problem. Turned out to be delivery valves worn and sticking.



John

 

[Jfam]

Problem Lingers On

Well the problem will soon be found as it is becoming more persistent.

For the first time yesterday it appeared at speed and not just on startup. For a 5 mile stretch the engine would sputter and then cut off. After a few seconds it would start and run for a +- quarter of a mile then stall. This pattern was repeated until I coasted into my driveway 5 miles later. The ticking sound intermittently appeared as a warning that she was about to stall.



The final significant clues (it seems to me) are:

1. The problem only –so far--has manifested itself when the outside air temperature is above 80.

2. The fact that it restarts after a few seconds seems very significant.



It seems that the relief of fuel pressure provides backflow enough to “unclog” or unstick whatever the problem is. Only conjecture, of course.



A rep at Geno’s said that he heard of s similar situation somehow caused by the Prime-Loc filter relocator. Since that’s the cheapest try, I’ll do that next. After that I guess it’s to the dealer. Does anything in the clues provide enough information for a locating the problem?



Seems that that injector pump and fuel solenoid are next, but I did check the solenoid plunger when she was acting up and it was all the way up even as it stalled. Any electronics?



Thanks.

Joe Fam

 

[illflem]

It sounds for sure like the IP. Don't go to the Dodge dealer, there is probably a Cummins dealer just as close to you.



Some folks have been able to clear up a sticking IP plunger with a double dose of diesel fuel additive that adds lubricity.

 

[Jfam]

Prime-Loc Removed

On Joe G’s advice I took out the Prime-Loc fuel filter relocator kit last night. It did not appear to have any blockage anywhere, but at least I have eliminated one more suspect. I did notice that the hose running from the lift pump to the prefilter heater screen had a sharp bend in it. It is a NEW house that came with the lift pump installed a few weeks ago. I was able to pinch the bend almost closed.



Since the problem existed both before and after the lift pump installation, I am inclined to think the hose is not the problem, but would like to know if anyone considers that sharp bend (which flattens the hose noticeably) abnormal.



Thanks,

Joe Fam

 

[illflem]

The problem with a partially kinked hose like that is that the more it gets kinked the easier it becomes to do it especially after the hose gets hot. What will eventually happen is the hose will leak at the kink.

 

[Jfam]

PROBLEM SOLVED!

Bill was correct in his last post on the problem: IP!

Piers of Piers Diesel nailed the one clue that linked the problem directly to the IP rather than the lift pump or overflow valve: the engine would “stick” at a certain speed--e. g. 30 m. p. h. --for a stretch. This was accompanied by the tapping noise that may also be noted with a defective lift pump or overflow valve. But in the latter two cases, the engine would not stick at a certain speed.

A mildly souped-up pump was obtained from Piers Diesel for $1,200. Piers was VERY helpful and talked to me at length about the problem and installation procedures. I did not have the time or the help (really it takes two people) so I had a local dealer do the job for $300. It’s been in for about 1000 miles now and all is well.

Thanks to Bill Fleming, Joe G. and all others who helped along the way.

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