Here's what I have going on. I have a 74 351W in a 52 ford. It recently started hesitating alot under a load going through the gears. I replaced coil , plugs , ignition module , fuel filter , checked timing then I replaced the fuel pump and it ran great with no problems... 30 min later down the road it started hesitating just a little and now a few days later she's falling flat on her face again. Any help would be greatly appreciated. I'm still leaning towards a fuel problem considering it ran great once I replaced it.... is it possible the new fuel pump is failing as well.? Thanks for your help...I'm at my wits end
What is the condition of the inside of the gas tank? That car is 65 years old and if the original tank is still in it it may be full of rust that is being loosened by driving vibrations combined with the solvent action of ethanol blend gas. Try changing the fuel filter again and cut open the one you remove and inspect it for clogging.
I had a 69 Torino with a 351 W, that had a hesitation/stumble. It turned out to be a bad vacuum advance diaphragm at the distributor.
Remove the fuel line on the carb side of the fuel pump, then crank it over into a container and see how much flow your getting.
What Carburetor ? Many manual fuel pumps are now off shore made and this is reeking havoc on a lot of forums internals are causing higher than normal fuel pressure many are 8-10 psi Edelbrock and AFB Carbs like 4.5-5.5 psi max Holleys with adjustable floats can handle up to 7 psi, you need to check the fuel pressure if it exceeds the specs I posted you will have to add a regulator.
Check the accelerator pump too. It should squirting a steady stream of fuel all the way to wide open throttle.
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