6.9L diagnosis
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More Turbo
Joined: Mar 2008
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6.9L diagnosis
So I posted this in the 80-86 forum, then found the diesel forums, and decided to repost.
So I have an 86 f250 4x2 blah blah, with the venerable 6.9L diesel in it. The engine smokes a little under load, and hardly has any hp/torque left in it. It even has died a few times while running, and has problems starting when its pointed up hill. I ran a compression test, and everything turned out fine. I think the problem is in the fuel delievery, as thats pretty much the only thing that can kill a diesel when it gets running. I only use the truck for dump runs, and I dont mind really tearing into it to find out whats going on.
Any suggestions on where to start?
I heard that to diagnose the fuel system up to the injector pump you can splice in a piece of clear tubing and check for air bubbles... sound like a good idea?
If this issue is discussed somehwere else, or you have any sort of insight, lemmie know.
So I have an 86 f250 4x2 blah blah, with the venerable 6.9L diesel in it. The engine smokes a little under load, and hardly has any hp/torque left in it. It even has died a few times while running, and has problems starting when its pointed up hill. I ran a compression test, and everything turned out fine. I think the problem is in the fuel delievery, as thats pretty much the only thing that can kill a diesel when it gets running. I only use the truck for dump runs, and I dont mind really tearing into it to find out whats going on.
Any suggestions on where to start?
I heard that to diagnose the fuel system up to the injector pump you can splice in a piece of clear tubing and check for air bubbles... sound like a good idea?
If this issue is discussed somehwere else, or you have any sort of insight, lemmie know.
New User
Joined: Sep 2007
Posts: 20
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From: with the cows
I can only help you with your starting problem. You will need an injector installation kit from the auto parts store. This will replace the plastic tee fittings and the lines on the injectors along with the o-rings underneath them because air is getting into the fuel system and letting the fuel drain back to the tank. And when it dies when running is that shortly after you start it? if so the that is just the fuel left in the injection pump getting replaced by air. So replacing the return lines may fix both problems.
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More Turbo
Joined: Mar 2008
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Thanks for the info, and yes, it dies shortly after it starts. And could the improper combustion cause the smoke that occours under load? I really wish I could tell exactly what color it is, but that a little difficult when climbing a hill at 50mph... Ive determined that there is no water getting into the cylinders, and its not burning any oil...
Thanks a bunch, headed off to the store to get the injector rebuild kit, but more advice on the problem is more than welcome...
Thanks a bunch, headed off to the store to get the injector rebuild kit, but more advice on the problem is more than welcome...
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
If your truck still has the OEM water seperator near the drivers side hood hinge, you may also be getting air into the fuel supply line.
Many have stopped the air by shoving a bolt in the drain tube.
Any idea how many miles are on the engine?
Are the injection pump and injectors the originals?
Many have stopped the air by shoving a bolt in the drain tube.
Any idea how many miles are on the engine?
Are the injection pump and injectors the originals?
Last edited by Dave Sponaugle; Mar 24, 2008 at 03:58 PM.
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More Turbo
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Yes, I have the stock water seperator. So you recomend just plugging the thing up?
The truck has 186K on it, I believe... Its a family thing, so its not like I bought it without knowing how many miles were on it, alltho it very well could be 286k...
The injector pump is stock, and the injectors were replaced "sometime in the past..."
The rebuild kit helped alot, there is definately a difference in power. There is still some smoke at startup and when its under stress.
Here are some interesting things that I found while inspecting and cleaning off the injectors:
2 of them had a metalic gunk buildup all the way from the threads to the copper washer, with a brown ooze all over.
1 of them came out completly covered in oil. That one concerns me the most.
Any ideas?
The truck has 186K on it, I believe... Its a family thing, so its not like I bought it without knowing how many miles were on it, alltho it very well could be 286k...
The injector pump is stock, and the injectors were replaced "sometime in the past..."
The rebuild kit helped alot, there is definately a difference in power. There is still some smoke at startup and when its under stress.
Here are some interesting things that I found while inspecting and cleaning off the injectors:
2 of them had a metalic gunk buildup all the way from the threads to the copper washer, with a brown ooze all over.
1 of them came out completly covered in oil. That one concerns me the most.
Any ideas?
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
What shape are the valve cover gaskets in?
The oil probably came from there, after it was around the ouside of the injector it just stayed there and cooked.
Any chance the metallic looking stuff on the threads was Never Seize?
A small amount of smoke is rather normal.
The harder you are on the go pedal, the darker it will get.
The oil probably came from there, after it was around the ouside of the injector it just stayed there and cooked.
Any chance the metallic looking stuff on the threads was Never Seize?
A small amount of smoke is rather normal.
The harder you are on the go pedal, the darker it will get.
