1986 carb idle trouble

e.sedgwick · 12-21-2006, 01:11 PM

Hi
I have a 1986 f-150 carbed 4.9 L that idles very rough and emits black smoke. I am replacing vacum hoses but I don't think that is what this is. The truck has 53435 original miles on it. I have replaced plugs,wires,roter button and cap. It has a new thermostat but runs cool. (Running rich?) Any ideas would be appreaciated.THe choke is open when the block has some heat

mechhound · 12-21-2006, 02:15 PM

Quote:

Originally Posted by e.sedgwick

Hi
I have a 1986 f-150 carbed 4.9 L that idles very rough and emits black smoke. I am replacing vacum hoses but I don't think that is what this is. The truck has 53435 original miles on it. I have replaced plugs,wires,roter button and cap. It has a new thermostat but runs cool. (Running rich?) Any ideas would be appreaciated

Yes the black smoke indicates it is running rich. The first thing to do is make sure the choke butterfly is opening up, if you haven't already done that.

e.sedgwick · 12-21-2006, 05:35 PM

The choke opens. I am thinking electronic module control on distributor?

mechhound · 12-21-2006, 07:19 PM

Quote:

Originally Posted by e.sedgwick

The choke opens. I am thinking electronic module control on distributor?

My next guess would be the float in the carburetor has a hole in it and is partially filled with gas, or the needle and seat in the carburetor isn't seating as it should. I don't think it's an ignition problem. Hopefully someone else will chime in here and say what they think.

rhandwor · 12-30-2006, 08:42 PM

I would rebuild the carb. running rich is usually a carb problem I think the previous idea of a leaking float is where I would check first.

e.sedgwick · 02-15-2007, 12:22 PM

Thanks guys
Rebuilt carb,truck run like a sewing machine

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