Somebody help!! I bought this truck a few weeks ago with a really rough
idle, i took it in and the mech said that my intake manifold gasket
was leaking and the manifold itself was warped. so 400 bucks, a
resurfaced manifold, new air intake manifold gasket, and adjusted
valves later ive got black smoke in my exhaust, fuel odor, and really
bad fuel milage. But heres the odd part, it will run really rough for
about 20-30 minutes after warm up then the problem will just go away
and everythings back to normal. Ive checked the compression (fine),
mech said the carb was working fine, spark plugs, cap and rotor (new). i looked in the sight glass and
the fuel level was really low in the float bowl when the engine was cool. i havent checked the fuel level at operating temp (and honestly i dont know if
the fuel level should differ). also when i tap the throttle the smoke seems to turn white but at idle its black, i had oil consumption diag'ed, mech said no oil consumption either. anything will help
thanks,
-manuk

 

I would say the problem lies with the electric choke. When it is running rough like that and belching black smoke take the air cleaner cover off and with a screw driver manually open the choke if it is still held on and see what happens. My bet is the choke is staying on too long and flooding the engine. I had that problem with my 82 and I put a manual choke kit on it and got rid of the problem all together.

 

There is a diaphram on the valve cover side of the carb. caled an AAP diaphram ( Aux. Acellerator Pump) . Pull the vac. hose off and see if there is gasoline coming out of it , the diaphram may be cracked and sucking gas into the intake. I believe cylinder # one usually gets flooded. After the engine warms up the tvsv shuts the vac. off and the fuel leak and it will idle fine.