General Category > Quadrajet Carb Talk and Tips

78 Qjet stuck on fast idle?

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wazzabie:
This is a 1978 4bl qjet.  I pump the gas peddle once and from a cold start, the fast idle is at 1700 rpm.  I'm trying to get the carb to normal idle which is around 700 rpm.  How soon after starting a cold engine should the rpms go to 700 rpm? 

Cliff Ruggles:
What is the carburetor part number?

What application?

wazzabie:
Thank you for the reply. 

The model number is 17058213.  The qjet is the original carb to a 78 K5 Chevy Blazer with HD federal emissions.

wazzabie:
Also after about 3min at high idle (1700 rpm) I tap the gas.  I notice that the high idle cam falls down but it still runs at 1700 rpm.  I have not placed the vehicle into drive.

Cliff Ruggles:
The choke flap should be fully open after 3 minutes run time and the fast idle cam should fall ALL the way down.  At this point it should be at curb idle and adjusted on the drivers side of the carb. 

Might help to lubricate the choke parts on the passengers side of the carb to make sure something isn't sticking and not allowing it to return to curb idle.....

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