6.9L IDI loses power and stalls

[DavidWarden38]

Hey everybody...I've been offered an 84 F250, 4 speed manual with 114,000 original miles, 4x4, camper special by a friend that I trust for $2,000. I took it home to evaluate and within a couple of days it developed a symptom that I'd guess is not a single part failure but more of an interaction among several components.

I've never owned a diesel before but I have a pretty good handle on gas engines. I've read quite a few posts about diesels are very finicky about air/water in the fuel, about how the injectorpumps and injectors need to be cared for, etc. So far, I haven't found any posts about the particular set of symptoms I'm having with this one.

After driving about 20 miles it started losing power and stalled within 1/2 mile. After resting a minute or so it started right up and had lots of power. A mile down the road the same symptom...losing power and stalled. Limped it home that way stopping at safe spots to rest the engine before it stalled in traffic. Stopped and started 6 or 7 times. Never would go more than a mile. Fuel filter is new and it has an after market water separator installed. No smoke on start and none under moderate load. It has an oil leak that appears to be near the front main seal. I also found fuel on the bottom front of the block.

Also noticed a sticky clutchplate when backing up. Pretty bad shake trying to feather the clutch to back up slow. Doesn't seem like it would be normal but I have very little experience with older trucks.

Love this forum and all the great input. Appreciate any insights!

 

[chillman88]

Welcome to the forum!

I also found fuel on the bottom front of the block.

This would be the first thing I would try to track down. Is there fuel around the injectors on top of the motor? Have you traced the fuel lines from the filter down to the fuel pump to see if that's where it's leaking? If it's leaking it could be sucking air and that'll cause problems.

How much fuel do you have in your tanks? The pickups in the tanks like to fall off and will cause it to run out of fuel at 1/4 tank. I don't expect this to be your issue given the symptoms but it's easy to check.

I assume this truck has dual tanks? Does the switching valve work (does it switch tanks normally). Does the fuel gauge work? I had the selector valve go bad on mine. It would run for a few seconds and then shut off because the valve failed part way causing a restriction to flow. It could suck fuel once it sat for a few minutes but running it would starve. If you get to this point, simplest way to check is run a rubber hose from the lift pump into a 5gal can of fuel and see how it runs. If it runs fine with no issues from the can you have a problem between the pump and the tanks. I bypassed my valve for a while until I could afford to replace the valve, cheap fix, needed a couple feet of fuel line.

Pretty bad shake trying to feather the clutch to back up slow.

Yeah mine will do that if I'm trying to feather it with some weight on it. Might not be normal but hasn't given me any trouble yet. If you start having other clutch issues I'd start looking into it.

 

[austin92]

I had the same problems when I got my truck. Installed a facet duralift and fixed the dying issue. Intentionally smoked the clutch taking off in 3rd one good time and fixed my chatter issue


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[hesutton]

Certainly sounds like a fuel supply issue to me as well. Would be nice to have a fuel pressure gauge on there to see what the pressure is doing when it stalls. My guess is the pressure is zero. Could be an issue with the tanks or tank selector valve as described above. Fuel pump my be garbage too. Like stated, run it off a jug of diesel straight to the fuel pump (passenger's side bottom front of the block). If it runs great, start working from the tanks to the pump.

Clutch.... likely uneven flywheel/disk interface. Not a huge deal, but all the bucking isn't good for your mounts, bellhousing, drive line... so on.

Heath

 

[The_Josh_Bear]

This is the exact same symptoms I had once. It ended up being a tiny little pre-filter on my electric pump, would get clogged, starve and die. Let the junk settle out a bit and it would fire right up and run good for only minutes. Like your issue it got worse and worse, hard to figure out. (BTW took me two really frustrating days to figure this out, cause I'm SOOO smart...)

Similarly if your fuel strainer is still in tact and there is junk in the tank the same thing would happen.

So i know you have a new filter but if there is anything plumbed in before the filter that might also catch junk, I'd look there and bypass it. Such as the water seperator(depending on where its plumbed).

Fuel on the front of the block?!? Weird. Leaking connections at your fuel pump maybe?

 

[nostrokes]

Welcome to the forum..

Like everyone else said look for leaks and restrictions first. Bettin your lift pump is on its way to the grave..

Does the oil smell like fuel?