First off the truck is a 74 f250 with a 300 straight 6 and a carter carb. so far i have replaced the fuel pump, fuel filter, all plugs and wires, distributer cap and rotor, and have cleaned and rebuilt the carb. However, there still seems to be some sort of miss or hesatation. Its kind of like the fuel and air ratio isnt right, but we adjusted that too and got it as good as possible. The truck idles fine and even runs fine but when you go to "goose" on it or punch it from idle or even take off fast it wants to bog down and sometimes almost die.

You can ease into it about medium throttle and then take it to full rpm and even if you punch it and wait a sec after it hesitates it will then go all out. when this happens you can hear the air being sucked into the carb. I hope I have explained it good enough.

Any ideas?

 

any ideas???

 

This is the most annoying part about owning an old ford truck. A lot of owners have told me it's just something you end up living with. Forget that.

If you are sure the vacuum advance unit on your distributor is ok and doesn't need replaced I highly recommend replacing all the rubber hoses on your vacuum system. That includes the one going to the transmission modulator and the vacuum reservoir. If those rubber hoses are leaking in anyway you are going to lose vacuum and you won't get a proper advance from your distributor. You may need to tweak the timing a bit after this just to be sure.

I pulled my hair out for months dealing with this problem and this one was by far the best fix I have found yet. The hoses are not the only cause of hesitation problems but for the cost of replacing them (it cost less than $10) it's a damn good place to start.

 

Sounds like the accelerator pump in the carburetor. I assume you've got a Carter 1 barrel; if so then the diaphragm cover is internal to the fuel bowl.

 

I have a 79 350 with 460 4b holly and its doing the same thing. I will check some of the hoses as well I guess. There doesnt look like many on this truck like some others.