92 F250 7.3 idi non turbo.

Over the course of about two months I've had a stalling issue. Under no certain or specific circumstance is this happening and it's only random.

Here's a little maintenance history. About 2-3 years ago, new GP's and GP controller. A year ago, reman IP, injectors and return line kit from Pensacola diesel. Couple weeks ago, new lift pump.

The most recent example of my trouble happened yesterday. Start the truck to leave work, warm up for a few, pull out into center lane to merge into traffic and it dies. Roll to a stop, put it in park, attemp a restart and it fires right back up but not without a puff of white smoke. It does this about 5-7 more times. Each time starting up right away and then dying immediately. Finally, I gave in and called roadside assistance on my insurance to request a tow. Agent says a tow truck will be there in about an hour. ***k me I don't want to wait an hour. I sit there for a minute to compose myself, flip the fuel tank switch to the rear tank, turn key, she fires up and stays lit. I sit there with the truck running, waiting for the high idle from cold start to drop so I call the insurance agent back, having them put my tow on hold. With my fingers crossed, she made it all the way home.

Now, on the drive home, out of curiosity I switched the fuel tank back to the front to see if that had any effect on the truck. It did not. I drove the truck home on a half tank of fuel in the front tank. After work today I didn't even attempt to futz with it. And no, I didn't drive it to work.

I've been chasing this for months and have reached my wits end. Am I missing something?

 

I could type for an hour and a half pointing out different possiblities, but honestly... i got nothin. I would definately monitor fuel pressure to the IP, and while i was at it, check the fuel shutoff solenoid in the IP

 

Your getting air,At the fuel head OR return lines OR at the tank switch OR at the fuel pick up lines,Use only one tank fill and drive if it happens a few times switch tanks if it happens again pick up line O rings are fine so it narrows it down to the switch O rings or the injectors etc best way is just replace them all and and return lines again and be done, And make sure the fuel heater isn't the cause there is a post on how to do that somewhere, Get a A/C pro O ring kit its has all the you'll need.

Its a PITA but once its fixed correctly it will work trouble free for many years to come.

 

Oh use some oil when installing any O rings to help them set.

 

You burnt half a tank going home from work??

That must be an expensive drive every day.

 

Does the truck cut out if you have two full fuel tanks? That is the first thing I would do...fill both tanks and run on just one of the tanks. If it stalls out of the gate switch to the other tank and repeat. If the truck stalls regardless of which full tank you run on you can eliminate the tanks as your problem.

I run a Stanadyne fuel system product in my truck, do you run any type of additive? If not, you might want to try some; many folks seem to run Diesel Kleen. Your IP might be lacking a little lubrication. How old is your fuel filter and have you checked it for water?

I would try these before I started throwing parts at the engine.

Just a few thoughts. Good luck and keep us posted while you troubleshoot the truck.

 

Nothing is truly random when it comes to mechanics and diagnosis, you just haven't noticed the pattern yet. I see two things in just your short example, the truck is always moving/accelerating when it dies and it's on the front tank. OK so that lends me to look first at something loose from the fuel tank selector out to the front tank.

You apparently have a whole month of evidence as to what it could be. Pay a little more attention, do some testing and put a little thought into it and you'll find what's wrong.

For example;

When it dies push open the schrader valve on the filter, does pure fuel come out?

How long does it take to start, air in the IP will generally take a few cranks?

Wire in a light bulb with the FSS, does it stay lit when the truck dies?

Does it ever die just sitting still, stopping, turning right, turning left, etc?

Etc Etc Etc

 

The whole "fires right back up" thing does not sound like air intrusion to me. I had this happen from a restricted fuel return line to the tank. Gunk built up where the hose fit onto the fuel selector switch to be exact. You can diagnose this by taking off the fuel return hose at the back of the engine and see if it stays running with the fuel pouring into an open container instead of back to the tank. One symptom of the restricted return line (in my case) was it would start and run, then the diesel clatter would gradually become softer and softer and the rpm's would drop until it stalled. It would fire right back up, and run anywhere from a few seconds to a few days. Very random very aggravating, very easy to fix once I figured out what the @!?$? It was...

 

Is that all?! I thought your daughter just turned 14 or something!

My friends truck did the same thing. It was the fuel tank selector motor randomly getting stuck between two tanks.

 

Seeing as it starts right back up it wouldn't seem like its air intrusion. The fuel return line and I rings are a month old. Replaced them because of this same problem.

I'm led to believe it's the FSV or related because it started and ran all the way home after I switched to the rear tank and back to the front. I haven't checked for pressure at the fuel head. It has cut out while turning right before and just going straight under acceleration. It has wanted to stall while just idling but if I goose the throttle and start moving its good.

The diesel clatter does slow down and so does the idle then it dies. I do use Diesel Kleen every time I fill.

The fuel filter was changed less than 2 months ago.

 

Yeah, that. That would identify or rule out a sporadic electrical issue...

 

That's the solenoid on the IP that has the single wire going to it, correct?

 

Ok. I just came in from running the truck and trying to get it to die. It didn't. I flipped between the tanks while driving and while idling. Drove it and let it idle for about 20 minutes. With the truck running, I didn't put a gauge on the fuel head but did get a good deal of fuel out of it. Then, I turned the truck off and depressed the schrader and just got a little pssst out of it. I should note too, when I initially started the truck it took just about 10 seconds to start. I didn't start it at all yesterday and it's been fairly cold throughout the day and very cold in the mornings and at night.

 

You never say if your truck is an automatic or manual?

There are several wires going to the IP. 1 on the passenger side is the fast idle. If it's an automatic then there are several wires going to a plastic part this is for the tranny.

On the drivers side of the IP itself is 2 wires. The one more forward is the cold start advance, the one behind it is the FSS, this is the one you need to check out. It's a BIG spade and to remove it you should have to push on a tab on the plug before it will pull off.

Run the engine and then pull off the wire, is this what is sounds like when it dies? Is the wire loose? Etc.

If you want to watch it then grab one of those cheap LED dash light things they sell at auto parts stores and wire it so that it's positive wire is connected to the FSS wire and the other grounded. This should give you a light that stays lit as long as there is power to the FSS and doesn't draw much juice.

 

+1

It does not have to be an LED; any normal 12v indicator light. I would do this next.

Roy