I have an 87 f250,it starts and idles fine. I drive about 4 blocks and it starts to "buck" I let off the gas it stops bucking. I get back on the gas it does it again. I've had a heck of a time. Does any one else have a suggestion?

 

Just bumping this for you as it hasn't seen any input. Can you elaborate on info...has it had a tune up? Is the CEL on? Let us know so we can help you diagnose the problem.

 

The first thing I would look at is fuel pressure. If your 87 is EFI (I don't know if Ford went EFI in 87 or if it was 88), test the pressure on the fuel rail, if it is low (I wish I knew the psi to look for. Engine size might matter), then look at the filter, and then the pumps starting with the high pressure pump on the frame rail, moving to the in tank low pressure pump(s).

Sorry I'm not much help. I'm sure you will get much more detailed answers from the experts on here. I'm still learning about my 88 f250 I've only had for a couple weeks.

 

EFI started as an option in '85 and became standard on everything in '86.

 

Except 460's and 351H.O.'s over 8,500#
Those went EFI for the '88 model year.

 

Changed everything up to plugs, wires, cap and plugs. Including fuel pumps.

 

Did the problem start after replacing those parts or were they attempts to fix it?

 

What engine is in your truck?

 

The engine is 300 efi, I changed parts to correct the bucking. I purchased another 300 thinking I might change the old one out.
I even had the valves replaced.

 

Have you changed the TFI module?
Have you measured the fuel pressure?
Is the fuel pressure regulator leaking?

 

New fpr the only thing I have not changed is the frame.

 

I had this happen recently on my car. It was a frayed wire in the ignition system. Tedious work, but go through your wiring carefully and look for problems. Even if you have to use a multi-meter to check for continuity.

 

Info is still quite vague. What is running fuel PSI?
Have you checked the TFI module? I know on the older trucks, the TFI is located on the distributor. On later trucks, the TFI module was relocated to the driver side fender, with a heat sink.