GMC/Chebby 2.8 idle problem

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nothingbutdarts

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OK, I know it's not a MOPAR but, I still have to get it running for a friend. 1991 2.8 V-6 in a little S10, throttle body. It will start, and you have to keep it running with the throttle pedal or it dies, if you drive it, you have to play with the throttle or it will stumble & die but, once you get it to speed it runs just fine till coming back to idle, then it just dies out again unless you get on the throttle and feather it. Any ideas of where to start?

Thank You!
 
vacuum leak


I would spray some carb cleaner around the throttle body and intake...check vacuum hoses which im sure there a quite a few ....just to start
 
;)

did you find anything with the vacuum ....if that don't work, I have some other ideas

is the MIL (check engine) light on?
 
I would check and clean the IAC valve. Most of the time, IAC problems will not set a code or pop the CEL on.
 
ck. fuel pressure only needs 10/12 psi for tbi also the iac will read 0 on counts if the tbi base plate gasket sucked in. the replacements had a metal lineing this was a big problem on the tbi set up.
 
If it,s a 2.8 TBI motor,they have TBI base gaskets problems,fuel regulator spring rusts out,the fuel pump should be putting out 12.5-15.0 LBS of pressure.If it,s a high mileage motor,timing chain wears out,as it,s a nylon gear.Have seen cam lobe problems as well.Do check the IAC motor,by removing the connector and seeing if it makes a difference.The intake manifold gasket splits open after awhile and cause a leak also,mrmopartech
 
good call on the TBI

I also checked and all I found for a fuel pressure spec is 14-16 PSI
 

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I would also check the wires and connector to the IAC ...I had a dodge van that the IAC was good but the wire was broken behind the connector and that was the whole problem :hmph:
 
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