I am not familiar with carb'd engines and just purchased a cheap 1985 Iroc with a carb 305. When cold the engine cant stay idling and the car dies. but if i tap the gas and keep the rpms above 1000 it'll warm up and then starts to hold idle but if you rev it high it'll come back down and stall then once the car is really warmed up to near normal temp its holds idle well and drives great.

gas is low and i was going to try and fill it and see if that helps but i didnt see how this could help because i dont think it would keep starting without gas.

any ideas? what can i try? i need to start learning about carb'd motors to get an idea here.

thanks

 

Sounds like your choke isn't working. There should be a green wire coming off of your carb on the passneger side...it's hooked to a round cylinder looking thing. That's your choke. Check this for 12v when the car is running. If that's not working or not getting power your car won't go to high idle when cold because the choke isn't working, thus won't stay running. The idle will run high till the ECM feels the car is warm enough. When it is, when you press on the throttle or "Kick it down", it'll drop back to normal idle once it's warmed up enough.

 

Good to know! Thanks, i'll def give this a try, unfortunately i cant try until the weekend. If there isnt power going to this wire then its just a matter of finding where the wire went bad or became disconnected? Where does it run to?

 

I don't now the exact circuit because mine works. Trace the wire back, you'll probably have to dig into the loom to find where exactly it goes. Not sure if it's to the fuse box or somewhere else like the ECM. Sorry I can't help more than that. My bet though, is that your choke is what's gone out on it. Rarely will you lose power to something like that unless someone has gone in and hacked up your harness.

Follow the link I'm putting in here. You'll find a picture a guy posted with a red box around a rod on the carb. Below that box is a black circular thing with a electrical plug coming off of it. That's your choke. This isn't exactly the carb you have, but that's what your choke will look like as they haven't changed much in the last 30 years.

https://www.thirdgen.org/forums/carb...g-my-carb.html

 

cool, thanks. i'll def try it out. hope thats all the issue is.

 

You know to pump the throttle once (twice if it's really cold out) before starting, this will prime the engine by firing a shot of fuel from the accelerator pump but more importantly sets the fast idle... if the carb is working correctly, you shouldn't have to touch the gas after starting if you pumped it first and the idle should sit around 1500-2000 rpm until you touch the throttle again to kick it down. If the engine wants to idle low and stall when you first start it, try cleaning all the linkages and moving parts on the carb.

 

Hmm, i'll try that too! I am a newbie with Carb's. I didnt pump before turning the key but i pumped once or twice while turning the key for the second time but it still didnt go over 1000 unless i tapped the gas.

Friday/sat will be good this weekend so im gonna check it out then.

I have seen carb cleaners and such in stores. Hows the procedure on using that stuff? So i remove the round filter from above and then jsut try to clean anything up that i can?

 

Ok, so i found the plug that connects to the choke and it was disconnected! so i connected it and still didnt fix the problem.

More important, i checked all the linkages and played with the carb and all the little parts right behind the electric choke sensor/piece or whatever it is seem to be loose and not really working together. Also i can push on the choke sensor/peice thats mounted to the carb and it moves! so its def broken/loose.

Think i may need to rebuild these linkages/connections? I got the car to idle for a few seconds but then it just died again.

 

did ya check to see if that wire is actually connected and working properlly?

 

I didnt have a volt meter at that time but i have one now so on Saturday i'll give it a check.

SHould it have voltage when ignition is in the 'ON' position or only when the car is running?

 

Yes.

 

lol thought so.. I may just go out and get a new replacement carb and be done with it. and if problems continue, who knows what i'll do with it then.

 

It should have 12V to it only when the car is running (it's wired to pull off the alternator).

If it looks really gummed up you may consider a rebuild, which is primarily a good cleaning and replacing the soft parts. First though, spray the choke linkage down real good and make sure the thermostat is getting 12V and that the choke plate slowly opens as the engine runs. It should be fully open after about 5 minutes.

Tweaking it with your finger doesn't indicate it's bad. It's held open/closed with a bimetal spring inside the cover that doesn't take much effort to overcome.