i HAVE A 79 F 250 WITH A 351M ENGINE. IT STARTS GOOD AND RUNS GREAT AFTER IT GET SOME SPEED. BUT WHEN YOU FIRST MASH ON THE GAS PEDAL IT SPUTTERS AND ACTS UP. NEW WIRES ,CAP, ROTOR BUTTON , PUWERVALVE AND PUMP IN CARB.COULD IT BE MISS WIRED OR WHAT. I JUST BOUGHT IT.

 

Hi Coach,
I recently had a similar experience with my son's truck.
I thought it was the accelerator pump also, like you mentioned. I thought it was starving for gas, but found the opposite to be true.

After taking the carburetor apart I found a bad float, it was cracked and saturated causing an extremely rich condition which does not work well at low RPMs, but would run ok at higher RPMs.

I would keep looking into the fuel system / carburetor area for the answer to this problem.

Sounds like the ignition is ok if it runs good at high RPMs.

Phil

 

What Phil said is probably pretty close to being right on the money, did that on my 400, it was the carb.