Rough idle on warm start

[libsys]

I'm getting a rough idle and smoke when starting after the truck has sitting for awhile, like an hour or so. Once it settles down, the idle is fine. Cold starts are no problem, fires right up and idles smooth. I thought maybe air intrusion, so I replaced the return lines. Didn't seem to make a difference, but it was time for new ones anyway. Engine sounds normal, just stumbles around when started up warm. Any ideas? Thanks!

 

[Kizer]

Air intrusion can occur at any point, in the fuel system, between the fuel pick-up tube (in the tank) and the top of the injector.

Sounds like air to me.

 

[libsys]

It sure feels like air, although I would expect that to affect my cold starts as well. I haven't checked the connections from the tanks to the lift pump, so I guess that'll be my next step.

 

[Kizer]

I would expect that to affect my cold starts as well

I agree ... The idea is to eliminate the possibility of air in the system first.
FYI: My '93 IDIT had "erratic" air intrusion, only when on front tank, turned out to be a bad hack (by PO) at the tank selector valve.