Problem with high idle.... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Da Bomb · 01-31-2004, 01:40 PM

I have an '86 chevy K20 I use asa barn/plow truck. Recently it began to have a fast idle and foaled out the plugs. I repaced the plugs, got it runnig and found that the high idle would not kick down even after the truck came up to temp.. I remove the Rochester Q-jet nd had it rebuilt but this did nto solve my proble (looks shiney though!)
My question is...what controls the high idle? there is what looks like a temp. sender mounted in the t-stat housing that is wired back to a plug on the front left corner of the carb.
I'm at a loss and really am reluctant to spend $$ on a barn truck. Any help would be greatly appreciated.

Thanks,

Matt
in Freezin' NY

Deltaskier · 01-31-2004, 01:47 PM

The cheapest things to check & replace for high idle are the vacuum hoses. A vacuum leak would cause high idle.

That & make sure your vacuum advance is hooked to the correct spot & not to a full vacuum port.

**swervin ervin** · 01-31-2004, 04:08 PM

You need to check the choke. It is probably closing on you and causing the high idle and plug fouling.

Da Bomb · 01-31-2004, 04:15 PM

the choke light is on in the truck..but its been on since last summer and this problem is only recent (4 weeks). When the carb was rebuilt they replace the bi-metallic heat riser assembly. what else should I check regarding the choke?
Thanks...

Matt

01-31-2004, 01:40 PM	#1
Da Bomb Registered User Join Date: Jan 2004 Posts: 2	Problem with high idle.... I have an '86 chevy K20 I use asa barn/plow truck. Recently it began to have a fast idle and foaled out the plugs. I repaced the plugs, got it runnig and found that the high idle would not kick down even after the truck came up to temp.. I remove the Rochester Q-jet nd had it rebuilt but this did nto solve my proble (looks shiney though!) My question is...what controls the high idle? there is what looks like a temp. sender mounted in the t-stat housing that is wired back to a plug on the front left corner of the carb. I'm at a loss and really am reluctant to spend $$ on a barn truck. Any help would be greatly appreciated. Thanks, Matt in Freezin' NY

01-31-2004, 04:08 PM	#3
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	You need to check the choke. It is probably closing on you and causing the high idle and plug fouling. __________________ Mike 1985 Chevy C-10

01-31-2004, 01:47 PM	#2
Deltaskier Registered User Join Date: Jan 2004 Location: Montgomery, TX Posts: 73	The cheapest things to check & replace for high idle are the vacuum hoses. A vacuum leak would cause high idle. That & make sure your vacuum advance is hooked to the correct spot & not to a full vacuum port.

01-31-2004, 04:15 PM	#4
Da Bomb Registered User Join Date: Jan 2004 Posts: 2	the choke light is on in the truck..but its been on since last summer and this problem is only recent (4 weeks). When the carb was rebuilt they replace the bi-metallic heat riser assembly. what else should I check regarding the choke? Thanks... Matt



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