hey, I'm new here and I'm wondering if anybody could help out. I have a 74 F250 highboy with a 390, automatic transmission(i believe a fmx). The truck was running good, then one day it just randomly sputtering at idle but it would go away. Also while driving the truck, it would run fine drive fine except if u would try to get into it. The truck would bog but would clear out and run wide open most of the time.

I have done the following:
rebuild the carb
new fuel filter
new plugs and air filter were put in before this started
checked cap and rotor(they are new)
vacuum test( good solid 19psi)
fuel pressure test(steady 6psi)
new coil

After i put the coil in it seems to help but it eventually went back to this. Then i just put in fuel treatment out of desperation and that seem to be helping for like 2 days. Just tonight though the truck started running funning again...stalling too. Any help would be greatly appreciated...thanks.

 

points??? that might be whats causing it. but i dont have much knowledge when it comes to those lol. thats assuming yours dont have electronic ignition

 

Have you checked the battery voltage? If voltage drops at high rpm the duraspark ignition gets very weak and you will not be able to get full power from the engine.

 

it is electronic distributor and the voltage for the battery was 12.6. What about the ignition module?

 

Ignition module will usually cut off and on like you turned the key or die completely.
I would check your fuel filter again and make sure its clear. Could be dirt or rust in fuel tank.
When you get into it and it bogs then clears up some, sounds like it's not getting enough fuel.

 

yesterday i drove it and it was running pretty good except when i first started it but it was good after that. I was able to get into it more too with a hick up here and there but not too bad. i did look at the fuel filter and the gas looked alright. I did but a better fuel cleaner just to pour into the tank to see if it helps it. That way i can at least eliminate or zero in on that issue.