Welcome to DieselPlace

Go through all of your grounds. Remove and clean all contact areas then reinstall. Replace any grounds that are in questionable shape
Install a piece of clear fuel line on the return side of the Injection pump to help locate any air in fuel issues.
Change your fuel filter.
Change your glow plugs ( Use AC/Delco or Bosch brand only)

 

It’s probably a bad governor cage flex ring within the injection pump.The ring turns black as time and mileage progress which causes the ring to break away in small pieces and causes the return fitting to become restricted.

Another possibility along with a bad flex ring is a stuck servo pin at the bottom passenger side section of the injection pump.These sometimes stick inward and won’t return when the throttle is released.Another area known to cause trouble is the lever on the same side of the pump.They sometimes seize there midway where the pivot point is.

 

Here are the prone areas for trouble when it comes down to a rough idle or smoke.

 

Thanks for the replies! I think I'll start out as suggested with changing the glow plugs and primary fuel filter as these seem to be easiest and probably overdue anyway. The primary fuel filter has "2013" written on it, guess that doesn't bode well. As far as getting into the injection pump, would it be worth it to check out the lift pump first? Reason I ask about the lift pump is it seems pretty easy to check, but don't know if that could be contributing to my problem or not.

If I do end up getting into the injection pump I assume I'd have to pull it to check these things?

 

Thanks for the replies! I think I'll start out as suggested with changing the glow plugs and primary fuel filter as these seem to be easiest and probably overdue anyway. The primary fuel filter has "2013" written on it, guess that doesn't bode well. As far as getting into the injection pump, would it be worth it to check out the lift pump first? Reason I ask about the lift pump is it seems pretty easy to check, but don't know if that could be contributing to my problem or not.

If I do end up getting into the injection pump I assume I'd have to pull it to check these things?

The things I mentioned can be checked without taking the pump off.There’s not much to it once you’ve done it once or twice.

 

Didn't know they had a lift pump, my 85 doesn't. Unless it was added later.

 

There is no lift pump on these trucks, they have a mechanical pump on the front passenger side of the block and then the injection pump. When you do glow plugs like previous comments AC Delco G60, Be careful and cross your fingers when pulling the glow plugs that they are not swollen because they are a pain in the ass to get out if they are and hope they don't break. Replacing the injectors isn't a horrible idea I know with mine I have a little bit of a rough idle and a miss because I have an injector that sticks every once in a while. And I would definitely change the fuel filter and water separator

Sent from my SM-G950U using Tapatalk

 

Thanks all, going to be getting into this thing tomorrow, here's a short video of the truck idling after warming up a bit:

Hoping to smooth this out some.

 

Originally trucks after starting had a high idle until it warmed and then went to normal speed. If
Someone else who understands injector pump advance can chime in ...

 

The thing is continued usage of an injection pump with a bad flex ring will cause the governor cage rivets to be sheared off eventually causing metal grit and carnage to occur inside the pump.The first sign of a rough idle on engines with older early 80s pumps should be investigated asap to prevent further internal damage of the pump especially if the flex ring has failed 100%.

 

Crack each injector line if the sound of the engine changes then you know that injector is working.
If there is no change when you crack the line then chance are there is an issue with that cylinder.

 

That’s true.I’d be curious to find out if that flex ring is bad.I’m betting that it is especially if the pump was never overhauled beforehand.

 

The fuel tank and lines from it are steel. If it has seen any damp over four decades (-ie not from desert/west coast) these could be corroded and thin/holed. No I didn't think a tank with diesel inside could be , now I know different...

 

Just stated working on this truck again and thought some updates might help people with similar issues:

Hard starting: did glow plug job + new alternator - no issues now
Dome/courtesy light issues: cigarette lighter was shorting out, feeding current to dome lights, simply removed the bad cig plug, left the socket, no issues now
Dash problems almost totally fixed with new pcb.

Thanks for all the help guys!