I have a 1971 F100 302 with a Motorcraft 2brl carb with a recently replaced electric fuel pump. My truck runs fine at idle, but any time I give it any gas, it stumbles and shakes tremendously. The truck will shake in the 2nd half of 1st and 2nd gear, and in 3rd it begins to shake around 35mph, eases a little and shakes violently at 40+ mph. Since the shaking I reckon is anytime more fuel is pushed making my guesses be the lines, filter, or fuel pump itself; can anyone steer me in the right direction please?

 

Does it shake when you rev the engine in park? I just want to clarify that it is the engine shaking and not a mechanical component of the drive train, like the drive shaft or something.

 

Yes, the engine shakes at an idle rev. I just replaced the fuel filter and put on a slightly longer line so there is no pinching, but I'm still having all the same problems.

 

Bogging down, hesitating, stumbling from a dead stop or when accelerating at speed...typical 2100 series Auto-Lite/Motorcraft 2V carb problem.

The accelerator pump diaphram and check valve are his-tor-y, time for a carb overhaul. The parts come in the kit or can be bought by themselves.

D4AZ-9A586-A (replaced C2AZ-9A586-B) .. 2V Auto-Lite/Motorcraft 2V Carburetor Kit (Motorcraft CT-499D) / Available from Ford, autoparts stores.

Applications: ALL 1962/74 Passenger Cars/Trucks / 1966/74 Bronco's / 1969/74 Econolines.

Note: As original, the fuel filter fits inside a metal can that threads onto the fuel pump. Since most peeps are unaware, they install an inline fuel filter.

And since they are unaware, the fuel filter inside the pump rarely gets changed.

C4AZ-9365-B .. Corrogated Paper-Cannister Type Fuel Filter (Motorcraft FG-1A) / Available from Ford, autoparts stores.

Applications: Myriad I-6 & V8 1960/70's Passenger Cars/Trucks/Bronco's and Econolines.

* If the carb is marked Motorcraft, it is not original to the truck, you wanna know why? There was no such thing as Motorcraft prior to 1973.

In 1972, the US Gov't forced FoMoCo to sell Auto-Lite, as the gov't claimed FoMoCo had a monopoly on auto parts.

When this occurred, FoMoCo started in-house brand Motorcraft, transfering all the Auto-Lite parts/part numbers over to Motorcraft parts/part numbers.

If the Motorcraft carb is off a 1975 or later, it's a 2150 series carb, the parts are not the same as a 2100 series carb.

If the triangular shaped carb ID tag is missing, look at the base of the carb for an ID number...post what it is.