'96 12V rough run on startup

[Rogan]

then clears up after 15-20 seconds.. whatcha think could be the issue? truck runs fine, afterward.

[MnTom]

Two things come to mind. The first is an air leak. When was the last time you changed the rubber lines behind the fuel filter? The other thing that would cause the rough start is timing. To retarded and it will run rough until it warms up a little.

[ISX]

I'm afraid mine does the same thing. It's air getting in the lines. Park on a downhill and the problem is cured. Park on an uphill and the fuel drains back to the tank.

[bjytech]

Mine did the same thing till last weekend when I eliminated the fuel heater from the fuel system, Now the truck starts and runs great. My fuel heater was leaking pretty good, when I unplugged the wire connectors that go to the fuel heater they were filled with fuel from it leaking out through the wires that go in to the heater element.

[Rogan]

Thanks, guys. I'll look into the air/fuel deal.

--- Update to the previous post...

Apparently, latest news is, it won't idle., but will if you hold a slight pedal. revs fine. Air leaks checked for; none found, all is tight.

[ISX]

If the thing has an air leak it will idle fine when he starts it, then start petering out as the air is purged through the system. Depending on how much air is in it, it might kill the engine if you just let it idle. Sometimes just a little pedal on it for a few seconds bleeds it out, other times the thing has drained all the fuel and needs to be rebled. Mine had no visible leaks or anything, I took the entire fuel system apart and cleaned everything, put it back together, solved, though I have no clue what solved it.