Stumbles on startup unless I give it gas

[brad007]

I have a 1991 chevy k2500 with the 350 tbi that is stock. When I start it up, if I dont give it any gas, it will stumble, shake a lot, and eventually it shuts off. If however I give it a few revs on startup, it will idle perfectly fine. Also, if I start it up and let it stumble for a bit but then turn the key off, when I start it back up it idles fine. I replaced the fuel pressure regulator in the throttle body, but that didnt fix it. I think it might be the fuel pump? I want to get yalls opinion before replacing that though. Anyone got any ideas? Thanks for your help

 

[Ron88]

How about checking the temperature sensor the one by the thermostat housing. It tells the computer to enrich the fuel mixture on startup if the engine is cold. You can use an ohmeter to check it somewhere on this site there is a chart that shows how many ohms it should read based on engine temp. Hope that helps.

 

[RichLo]

How does the injector spray pattern look?

 

[Caman96]

Fuel filter was replaced when?

 

[PWC Repair]

The IAC motor controls the idle. On older engines they simply get dirty and don't work properly. Unscrew it and clean the pintle (tip) and passages. Easy peasy.

 

[Caman96]

The IAC motor controls the idle. On older engines they simply get dirty and don't work properly. Unscrew it and clean the pintle (tip) and passages. Easy peasy.

It is easy and often overlooked. IIRC, cleaning maintenance is something like every 60k.

 

[weaponoffreedom]

I have a 1991 chevy k2500 with the 350 tbi that is stock. When I start it up, if I dont give it any gas, it will stumble, shake a lot, and eventually it shuts off. If however I give it a few revs on startup, it will idle perfectly fine. Also, if I start it up and let it stumble for a bit but then turn the key off, when I start it back up it idles fine. I replaced the fuel pressure regulator in the throttle body, but that didnt fix it. I think it might be the fuel pump? I want to get yalls opinion before replacing that though. Anyone got any ideas? Thanks for your help

check fuel pressure, verify with spec, not sure where it should be, check.

fuel filter ever been changed.

have you done a tune up in a bit?

cam position sensor? (Under distributor cap)

ICM and or distributor / cap


I would look in that order, easiest to hardest. The cap could be corroded.