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Old 01-07-2012, 10:09 AM   #1
kellytheaker
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Join Date: Dec 2009
Location: ontario Canada
Posts: 412
87 chev 1/2 350 F/I cold start surging idle

the truck will go to fast idle and then drop to almost stall then pick itsel f up again and continue - when warm it improves but still a surge of up and down - just not as severe - is this an o2 sensor or ? the truck seems to always hunt for an even idle - thanks
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Old 01-07-2012, 11:01 AM   #2
ChevyTech
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Join Date: May 2004
Location: Minnesota
Posts: 4,621
Re: 87 chev 1/2 350 F/I cold start surging idle

A common cause of an idle that hunts up and down on these trucks is a lean fuel mixture, usually from low fuel pressure.

It is also common for the gasket under the TBI unit to leak vacuum causing idle issues.

Here is a thread on this topic:
http://67-72chevytrucks.com/vboard/s...t=surging+idle
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For those of you that are wondering why you are not getting replies to your thread:
Did you give the model, year, engine, fuel system type, and transmission information?
If it is modified from what came stock from the factory, let us know that too.
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Old 01-07-2012, 03:44 PM   #3
kellytheaker
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Join Date: Dec 2009
Location: ontario Canada
Posts: 412
Re: 87 chev 1/2 350 F/I cold start surging idle

thank you - i will certainly check the fuel pressure , tbi base and reg , then on to additional post info i read the other tips if its not fuel related , thanks it s a start .
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