Truck generally runs great when I drive it everyday. The only exception is once its warmed up, it will sometimes die when stopped in gear.

When I leave town for a couple weeks or so, I can start up the truck as if I was driving it yesterday. It will run fine and then I can start to hear it lean out and then die. I check the spin on fuel filter and it's full of fuel. So I pump the priming pump for a while and then crank it for a few 5-10 second bursts with no firing. So I crank while spraying WD-40 in manifold. I use that as opposed to starting fluid to preserve the engine. Doesn't work well but it works. After it fires off and it will be fine until it sits for several days in a row.

This has happened several times consistently as I described above when its sat for several days for whatever reason.

I've tried to explain it as precisely as possible so that maybe it will help determine where the leak is. So obviously there is fuel at the injectors and some in the lines but I can't figure this out. Is there a relation to the occasional stalling at idle and the main problem i described in the second paragraph?

 

talking about my 93 12v here in case there were any doubts

 

When was the last new fuel filter put on?

Or perhaps your fuel tank is not venting, and eventually there is too much vacuum in the tank to allow the lift pump to draw more fuel? How old is your fuel cap?

 

I believe the diesel cap is vented, and the gas cap not. The wrong gas cap would do this. Symptoms fit perfectly.

 

It's got a fairly new fuel filter. The locking fuel cap I have now I've used on my brother's 93 12v without this issue. Is the only fuel tank vent in the cap on the first gens? (I know my 3rd gen will start leaking out the top when I overfill it, I reckon through a vent).

So this problem of starting right up, momentarily running, and then slowly stalling, only happens after the first day of a long sit (like over a week)

The thing is, if it's been say four or five days since I ran it I can tell that it will lean out slightly but in these situations (after a shorter sitting time), I can save it from stalling if I can get the rpm's up fast enough using as little throttle as possible and hold it there for a few seconds then let it back down and it will settle out just fine and run fine for weeks. If I can successfully do it this way I avoid the lengthy recovery process after otherwise totally losing the IP prime (or whatever's going on).

Also possibly noteworthy is I have the idle screw in further than what looks like most guys run on their pumps. A recent tinkering with the fuel cone and star wheel helped a little with the temperamental stalling at stop light in gear. Perhaps these are totally different problems.

I know that the smoke screw tamper plate and silencer ring was missing when k bought the truck 2 yrs ago so someone else has tinkered with it.

 

well the sitting for a while and then running for a minute and dying can be explained by this. truck sits, fuel drains back into the tank, which it shouldn't, then the truck starts with what fuel is left in the IP and lines, then starts sucking air from the empty fuel lines and dies. then you prime the system and it starts up and runs fine.

the idle issue is probably separate, probably just set too low. set it to ~800 rpm

 

Easy enough to test. Take off the Fuel Cap, and start her up. See if the problem resolves. If that solves it, you need to start chasing a vent issue.

 

So to test this I should probably check the fuel lines after it has been sitting for a while and see if they are empty. If there was some sort of internal IP leak then I would be getting fuel in the oil, right?

If I were to set it to a position similar to what I've seen on most peoples trucks it would be way too low this leads me to further believe that there's something not quite right with the IP.

 

every pump is different. idle, fuel screw, star wheel, timing. no 2 trucks/pumps are the same

a bad diaphragm lift pump can cause a fuel leak into the crank case.