66 mustang, manual fuel pump.. will be driving down the road, and the car acts like you just shut the key off.. then sometimes, if you dont push the clutch in... it will sometimes start back up. and then backfire out the back of the exhaust... and i dont know what else it could be.. besides the battery being low on voltage? were having charging issues.. could that be it... has anyone had this happen before?

 

check voltage at battery with car running,,should be between 12.5 and 14.5 or so just siting there doing nothing, if less then 12.5 it's a charging issue,,,after that check you cantake the Negative battery cable off while car running,, if it still runs your electrical is ok,, if not then voltage reg or alt either way if one of these arenot working you gotta electrical issue going on and not fuel,, you gotta narow it down step by step and find a frien with a little experience with cars

 

Sounds like vapor lock.

 

Just my 2 cent here....had similar prob with 67 coupe when fuel filter was clogging up due to rust from the old gas tank. Rust particles got into the carb making it idle badly. Replaced the tank, filters, and cleaned the carb...worked fine after that. Put on a clear fuel filter and see if you have rust settling in the bottom of the filter...good luck and keep us posted on your findings...

 

i once had a similar issue as well.
I dropped in a new flamethrower II coil and distri.
The problem here was that one of the screws in the dsitri wasn't tightened properly (manufacturing fault), so the ignitor module was loosing ground.
Hence not work and not fire. through all the rattle and shock of not running (cluthc not pressed) the conact would connect again and drive for another 10 miles.
I usually had this problem under load (overtaking or uphill).
It took me a while to figure, but maybe you have the same issue. Loosing ignition.
I couldn't tell no-ignition from no-fuel apart when engine switches off. So investigate on that. Make sure all your cables around ignition are hooked up properly as well as engine ground.
but maybe the backfire out off the exhaust is a sign of unvurned gas igniting-> hence you're missing ignition, not fuel