Any help is greatly appreciated.......

I have a 78 F250 4x4 with a 400ci AT. The problem I am having is an intermitent stalling which won't let the motor accelerate, but will allow it to idle only. This problem usually begins after 5 or 10 minutes after a cold start. Any push on the gas once the problem sets in will cause it to stall. If I turn the motor off and allow it to cool it will give me another 5-10 minutes again.

I ran a fuel pressure gauge and confirmed 7PSI during the problem, so fuel is fine. The carb was just rebuilt, in the midst of the problem with no improvement.

I replaced the distrubutor pick-up coil, ignition coil and computer module with no success. I then removed the wires from the ignition coil & distributor to computer module to check continuity, all passed. Of course they were cool when I did the check, but visually they look good. The harness plugs look a little worn, but not sure where to get replacements.

Any ideas on what the source of the problem could be, or how to approach the components to isolate the problem. I was hoping to run some jumper wires to isolate the component or wire/plug.

Also, are there any components inside the cab that could be causing the power shortage to the computer module (i.e. ignition switch?).

Thanks in advance for any advice!

 

Where in the line did you do the fuel pressure test, before or after the filter? My first guess would be a clogged fuel filter. There's enough fuel flowing for idle, but perhaps not enough to go any faster.

You might also check the metal fuel line in the engine compartment. If it's close to the exhaust system, it can get hot and vaporize the fuel before it gets to the carb. There's a name for this, but it escapes me right now.

Another thing to do is inspect everything along the throttle linkage - from the pedal to the carb. Look for places where the linkage might be rubbing wires or harnesses. I have lots of stories of wierd electrical problems that turned out to be something as simple as a corroded wire under the dash or melted casings shorting out somewhere.

Good luck.

Kevin K.

 

Is the choke opening all the way? Once the engine is warm, the choke plate should be wide open. A partially closed choke would cause the problems you are having...

Marty

 

I suspect the choke housing needs to be adjusted, adjust the choke housing with the engine cold. Best time is early morning.