I have an 82 Chevy pickup with a progressively worsening problem. I purchased this truck last year and it ran fine for about 3 months. In the fall, after I had added 10 gallons of fuel to the tank, and ran about 8 miles, it began to run really rough. At 60mph it revved up, and then dropped down to 45mph. I couldn't get it to go faster, and it lugged for the next 4 miles until it finally died. It would start right up after it died, but do the same thing for another 2-4 miles until it died again. It has gotten progressively worse. Now when it starts, idles, and then warms up in 5-10 minutes it surges and runs really rough, then eventually dies. If I try to drive it, it makes it 50 feet and then dies. If I wait a few minutes it will fire up, or if I pump it and hold it will start, but then dies in another 50 feet.
We have checked for air in the fuel return line; air in the supply line; vapor going to each cylinder; changed filters out; fuel is not gelled; reasonably sure there is no water in the fuel.
Is the injector pump failing? Governor retaining ring? Could there still be air? Why does it act up after 10 minutes of warming up?
Would appreciate any suggestions...

Do you have good fuel pressure after the secondary fuel filter? If so most likely problem is the injection pump.:(

Long ago there was a problem with the injector pump, it had some sort of plastic part that would come apart at about 60k and fill the pump full of junk. The pump had to be rebuilt and then everything was fine. I would have thought that problem would have been solved long long ago. I suppose that it is possible you have a pump that was sitting on the self someplace and was installed just a few years ago. To find out if that is the problem, you must take the small cover off the top of the pump. When you do, you can look down inside and see if it is full of black trash. The symptoms you describe are exactly what one I had in an ‘83 van did. The inside of the pump looked like it had rubber slivers in it. The only solution is a rebuilt pump. It can be rebuilt using stainless steel parts that will outlast the truck.

Sounds to me like bad fuel.... or somthing stirred up in the tank that has now possibly plugged your pickup tube? If the problem started when you put that 10 gallons of fuel in it, I would suspect that would be the best spot to start.

Checked inside the injector pump the other day for black particles and there are none. Perfectly clean. I thought about bad fuel, but not sure thats the problem either. Additives and another 20 gallons of fuel didn't fix the problem, actually seemed to make it worse. Will check the pump & pickup tube again.

Try disconnecting the fuel return line that comes off of the top of the injection pump, route the open end into a can and then start engine. Any better? If it helps, look for a restriction in the return line.:rolleyes:

Have air in the return line (ran a clear tube). Also found air in the fuel supply line (from the fuel tank to the primary filter). Reasonably sure that fuel lines are good. Could it be a flaw in the tank selector? Can't switch to the other tank because second tank dumps fuel on the ground.

Also, What is the fuel pressure supposed to be?? It has steady flow but how much is not enough?

Best bet would be to pressurize fuel tank with about 3-5 psi of air and check for leaks. Any leak will allow fuel to flow back to tank and remove upper level of fuel from primary filter, resulting in no start. If leak can't be located, easiest temporary fix is to install an electric fuel pump on the frame rail. This will pressurize your primary fuel filter and help eliminate the air. Sometimes a bad mechanical fuel pump can also be the souce of air leak. Remember, you primary filter is a siphon feed. Fuel enters from tank to filter to fuel pump and then to secondary pump. These siphon feeds have a history of being a PIA, hence the development of the later box filters from 84 on, that are pressure fed. Hope this helps.:grd:

The tank selectors themselves can also be a source of air problems.

Since it is a 1982, the fuel hose on the top of the tank may be brittle and cracked. And that is a job to drop that tank. Look down between the bed and cab and see if any fuel sign is on top of the tank although a crack make not leak much, but still let air be sucked in. Check your hose from the frame fuel line to your mechanical pump as they can also crack or the clamps may be loose.

Thank you all, will try checking hoses, etc. I appreciate all your help.