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92 C1500 Won't

07-21-2008, 05:20 PM
My 92 c1500 with a 350 has stopped idling. It runs good at mid to high speed but when you let off the gas and start to coast at low speed (5 to 30 mph) it will die. when you stop with the truck in gear it will die immediately. It also dies idling in park. It starts right up but you have to press the accelarator down about 1/8th. the truck has 102000 miles and is otherwise in great condition. Its my main drive that up until now has never let me down. i replaced plugs wires dist cap and rotor and fuel filter 20000 miles ago. Has a half tank of fuel. Any ideas would get me started. Thanks!!

07-21-2008, 08:03 PM
Could be the Idle air control motor.All you need is a 1 1/4" wrench to removed it.Plug it in after it is removed and have someone turn the key on and off.It should go in and out with the key on and off.If not,it is bad you can get one at any parts store.Try cleaning it first with Carb cleaner.

07-21-2008, 09:05 PM
I have also seen a bad pickup coil cause issues with low rpm stalling. A bad MAP or vacuum leak to the MAP will also make it stall a lower RPMs.


07-23-2008, 07:32 AM
The classic symptom is a vacuum leak (unmetered air which is not compensated by fuel).

Check all your vacuum lines to MAP sensor, the EGR valve, check hose to the brake booster, change the TBI gasket-to-intake are a couple places to start. Deeper problems could lie within the intake-to-head gaskets.

I've found if you have a bad or cracked vacuum line, Napa sells silicone-based vacuum hoses. These are much higher temp rating than the OEM versions, also they are ultra-flexible which comes in very handy as some of the GM lines have two different sized barbs to connect to (for error proofing at assembly). So the flex hose will easily accomodate a larger fitting whereas the standard vac hose usually isn't flexible enough to expand very much. The silicone hose is of course more expensive but well worth it, IMHO.

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