Help With Hestitation/Stumble Problem - Thanks

[palerider94]

Been struggling with a bad hesitation/stumble problem. Had posted previosly on this.

After changing intakes gaskets (may just be a coincidence) starting having a bad hestition/stumble with car when WOT or giving some extra gas when accelerating.

Took to local Ford guru - he called me told me he got rid of the stumble. Went and picked the car up and not a mile down the road starting having the same problem. Took it back - he swore it was running fine for him. We played with timing and springs on the the vacuum advance took for short test drives - about a block seem to run good not a speed demon but pretty good. Now one the way home same thing - 1/2 mile out same thing - hesitation & stumble with backfiring thru carb is back. Whatever the problem its seems okay on these short spurts as we were tweaking but problem comes back when it's driven more than block test drives we have been doing. I'll check timing tomorrow to seem if it's still where we set it tonght but really could use some ideas on what may be causing it.

Some background on the car:
1. New Holley, fuel lines, sending unit, choke is fine
2. Pertronix ignition
3. Good vacuum 20 psi
4. Spark is good tested that
5. Just put new vacuum advance thought that may be the problem

302 motor, 1970 stang.

Appreciate any help - starting to run out of ideas.

Thanks

 

[mfp4073]

Popping back through the carb is almost always timing related. There may be other stuff going on...but that is where I would focus....

If its crappy and timed right it will go out through the bottom, not the top.

 

[palerider94]

That is where we started. But if it was timing seems like problem would be obvious off as soon as you drive it (1st block). Like I said 1st block - test drives were okay - problem surfaces after you drive it a little longer distance.

 

[pabear89]

Replace the breaker plate in the dist. the bushing are prob worn out.


PB

 

[palerider94]

Thanks - I'll look into it. Would that cause the problem to get worst as the car runs more?

 

[tylerrocks]

I assume you ment the petronix drop in electronic ignition module, the one the just replaces points? If so it still needs a correct gap between the module and magnetic sleeve, I had the same problem as you, turns out the module moved a little and the gap was too small. It almost drove me crazy. Check the gap it could be a free and easy fix if its the problem.

Tyler

 

[palerider94]

I did check once - could not find the little plastic feelerthat cam with it - but used a metal feeler gauge and gap was correct .030 - I'll check again to make sure. thanks

 

[D.Hearne]

Also check for water in your gas. That will do just what you descibe. Diesel will also.

 

[jerry S]

also check for rust in your tank. I had stumbling and stalling problems that were incorrectly diagnosed as being carb, dizzy, and ignition related. I replaced the dizzy, ignition, and wires but the problem remained. After the rust was discovered and the tank was drained, we found enough rust in it to fill up a salad bowl.

 

[palerider94]

tank is pretty new. Replaced lines, sending unit, fuel pump and put a new paper type filter in. I think it's the distibutor and not advancing correctly. When taking for test rides - short distance - was running best at timing at 2 B. After a mile or so starting backfiring thru carb due to retarded timing. I Think PaBear is right - but paln on repacing dizzy instead of fixing old.