I have a 1985 chevy c 20 with 454 v 8 3speed manual on the granny. it has a problem idleing down. evan in nutral the engine races and idles rough. sometimes she will idle down annd run fine

Ant Cunliffe

Asked by Aug 10, 2014 at 12:07 PM

Question type: Maintenance & Repair

1 Answer


Sounds like the automatic choke is sticking. These were electric. The choke coil, on the carburetor, has a little electric heater in it. Over time the heater wears out and the choke doesn't open as it should. The choke gets power from the oil pressure sending switch. When the engine is running and there's oil pressure current flows to the choke. Start the engine and unplug the choke. Check for power. If you've got power, choke coil is bad. If not, check for power at the oil pressure sending unit. HTH. - Jim

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