boman

'81 chevy truck misfiring

'81 Chevy 1/2 ton 6cylinder

Misfires when changing into high (drive) with 3 speed auto tranny.

Seems like it wants to shut off until you let off the accelerator.

Comments appreciated.

bejay

could be alot of things, might check cap and rotor , might also see if it acts up with vacum advance unplugged.

Joe_F

I agree. Might have frozen advance weights.

boman

Thanks guys, I had also suspected the spark advance. I think this old truck had been sitting for a while before I got it. Changes into second fine, but when it goes into drive, ....

It also may need a modulator valve. It seems to not want to shift into drive until it is going about 50. I'll piddle around with it and see what it takes to straighten it out.