A few days back I was driving on the interstate and after about 1.25 hours of driving I noticed my truck start to jump a little, kind of like it was about to run out of gas. When I exited about 10 minutes later I came to a stop at a light and the engine died. It did not run out of get because I had just filled it before I left. I tried to start it and it could not turn over. After a few minutes I managed to get it started but as soon as I put it into drive it died. So now I'm trying to figure out what the problem is. After it sits for a while it usually starts right up. It idles just fine but as soon as I shift to drive it struggles for a few feet and then sputters out. I've since replaced all the fuel pumps and all the distrubutor components and still the same thing occurs. If anyone has any suggestions I would greatly appreciate it. BTW, the engine is the original 1985 5.0L EFI.

 

Sounds like the timing chain jumped.

 

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Well, I'm hoping that's not the problem. The engine was rebuilt about 3 months ago and has been running fine since then. The timing chain is brand new. If the timing chain were to have jumped do you think the truck would still run ok at idle speed?

 

It's possible. I had and oldsmobile one time that jumped, it ran like a race car at idle, but just popped and banged when you hit the gas.

 

It is similar to the problems you see when the timing chain is slipping (I just went through this), except that the slip usually occurs when you are starting it and it jerks the cam.

If you want to check, remove the serpentine belt, fan shroud (if present), and far. Take off the distributor cap. Put a large socket on the bolt inside the harmonic balance, then rock it back and forth to see if there is any slack between the crank angle and distributor rotor, this would be timing chain slack. Now there could also be worn teeth which cannot be diagnosed this way, but I doubt any of this is a problem if they did they job they were supposed to.

You need to do more diagnostic work. I would focus on the ignition system first. Pull the spark plug wire going to the distributor and see if you can draw a good spark when cranking it.

Check for vac leaks. This is inevitable if you have not replaced the stupid hard plastic factory vac lines with normal vac hose, they will crack in areas where they see heat. Check that the "coffee can" vac reservoir is not rusted (also inevitable). These can cause it to run like crap, though rarely stop it entirely.

Turn the key on and off several times and measure pressure on the fuel rail, you need about 35-40 psi. Don't tell anyone I said this, but you can do it with a tire gauge that clamps on (a push-type will probably relieve the pressure as you put it on). Be sure the SPOUT plug is still in place on the ignition module harness.

Throttle position sensor, ignition module, ignition coil, fuel filter are all things to look at. The inertial fuel shutoff switch is also failure prone, this will cause the pumps to shut off. The computer is possible but very, very unlikely.

 

I can't imagine it being the timing chain. The problem started while driving on the highway and the timing chain and sprockets have less than 1500 miles on them. I've checked the spark and it is good. I haven't found any vac leaks. Usually when I've experienced vac leaks the engine idles faster than normal but it idles normally. The fuel system has been completly redone and tested and it seems to be putting out sufficient pressure when I do the test like you describe. I went over the entire engine wiring harness today and redid many connections including the SPOUT wire which was holding on by a couple threads but it still does the same thing. I replaced the distributor cap, ignition module and the pick-up coil. still nothing. I also imagined it would be very unlikely that the computer could be the problem but I swapped a new computer with the original computer anyway and it did not do anything. I suppose I will test the compression next to see if anything is going on there. One other thing I'm thinking about it the ignition coil. I don't know if this could cause this type of problem or not. If anyone knows please share.

To give exactly what is happening: The engine idles fine and can be revved quickly. If you try to rev it slowly by just bumping the accel. then it struggles and dies. If I put it in drive the truck can drive on flat level surface but as soon as the accelerator is pressed the engine struggles and dies. Sometimes if it dies it can be restarted right away but usually it takes a few tries to get it started again. That's about it.

 

Have you checked the computer for trouble codes? If not, do that before doing much else. If you don't know how, instructions are online at http://fordfuelinjection.com .

 

The original Ford EECIV computer is rarely useful with its codes, but it is worth a check.

Check your throttle position sensor. Go to your computer and find pin "47", they are labelled but it is difficult to see. With the harness still in place, stick a piece of wire into where to wire goes until it meets the metal of the contact pin.

Hook a meter from that wire to ground. Turn on the key, but do no start the car. Slowly push the accelerator up and down, the reading should change smoothly.

If your coil makes good spark, it's not the coil. If you can take a piece of wire tied to the engine, put the other end 1" from the output stud on the coil, and still draw a spark, you're great.

Perhaps your fuel filter is clogged. Check your fuel rail pressure, especially when you try to move it and it's dying.

 

Oh I forgot the obvious- how sure are you that you don't have bad gas?