Vehicle is a 1986 Chevy G10 van. Canadian 4.3 V6 with a four barrel (M4MED?) carb. Automatic trans. 52,000kms on her.
I thought I had this problem licked, but it came back yesterday... (temp dropped to around 0'C)
Normally, the van runs really nicely, except for a touch of a lope. (This van sat for a few years, so I'm suspecting that the lope is caused by unequal compression due to corrosion, etc.)
The problem is, that when it's cold outside (it was around 0'C last night), I can get the van started fine, but within a few minutes the idle starts dropping... lower... lower... lower... stall. Usually when this happens and I'm driving around I end up using one foot on the throttle, keeping the revs up, and the other foot for the brake pedal. After five to ten minutes of this the van runs fine. When the idle is dropping, the exhaust smells strongly of fuel.
I've tried adjusting the low idle screw while the idle was dropping and there was no contact between the screw and the stop, indicating that the fast idle was still holding the throttle valve open to keep the idle up.
I haven't had the opportunity to pull the doghouse off and pop open the air cleaner when the van is running poorly.
From what I could see last night with my flashlight, while at the side of the road, there appeared to be gasoline leaking from the throttle valve shaft at the bottom of the carb.
The choke on this carb is electric, and still riveted into its stock adjustment.
This carb has been on and off this engine a few times, and disassembled at least once - so any adjustment could be messed up.
Now, for what I do know...
- Cap, rotor, wires, plugs (platinum) are new & timing is good.
- Air filter, PCV valve and PCV filter are new.
- Fuel filter is new.
- Gas is fresh.
- Thermostat is 180' and new.
- Oil & filter are new.
- EGR is new and correctly valved for this motor.
- Vacuum lines are OK and timing advances normally.
I've got two questions...
- What's wrong? Any help is appreciated.
- What kind of power is fed to the electric choke? Could I short it to 12v to test?