Alterian

I have a 1996 gmc sonoma with a 96 lt1 out of a z28. I havent got much help from this site in the past but figured Id try again. Just put a brand new wiring harness in. The issue is that when its cold it will crank and crank and I have to pump the gas pedal to get it to start. Once it starts it runs good. I can shut it off and it will start right back up, even up to like 3 hrs later as long as the motor is still somewhat warm. But if it sits over night or cools down then it does the same thing on the first start up. I have cleaned the maf sensor with no changes. Any idea what could be causing this issue?

Eshaw81

This could be a number of issues so I'll just comment on my experience. When this happened to me with other Gm vehicles, it always turned out to be a fuel system issue or one of the sensors. Since it takes awhile to start and only does this after truck has been sitting awhile, I would suspect you have a bad pump that isn't maintaining pressure.

Alterian

Ok that would make since. It seems to be worse when the truck is sitting on an incline

Eshaw81

Probably a faulty check valve either in the pump or somewhere in the lines. I would start with the pump 1st. And word of advice with the pump...go with a factory one or a walbro or you'll be doing it again.

Alterian

Ok thanks