98 jimmy cold starting

Asked by dahar Dec 31, 2015 at 12:56 PM about the 1988 GMC Jimmy

Question type: Maintenance & Repair

my 98 jimmy won't start in cold weather also runs strangely when it does start. it is like someone is pushing throttle when driving first faster then slower a difference of about 4000 rpms up and down up and down constantly until at idle then idles fine and steady. can see a difference on the tack.

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Rowefast answered 8 years ago

Sound like you have a vacuum leak. Take some carb cleaner and spray along the intake gasket, throttle body area, anywhere there is vacuum. If there is a leak the RPM's will pick up. Also it may be in the Air Idle Control sensor. That gets all gummed up and needs to be cleaned by taking it out, and also cleaning the port it goes into. You must make sure it seals when you put it back in as there is vacuum right there

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