Electrical: running headlights and heater makes jeep sputter?

Hello everyone, relatively new to this board, but have found many useful posts using search already. However, trying to hunt down this new issue I've been having.

The jeep is a 1979 cj5, with a fiberglass tub. It has the 258, with exhaust and headers being the only obvious modification.

After the jeep was sitting for a while, being driven only occasionally, it developed this new problem.
When driving with the headlights on, or the lights and heater (so mostly at night) it will start acting as if it is running out of gas, and even stalls sometimes completely. If I let it sit for 30 seconds it will start up and run fine, well at least until I turn the lights or heater on again...

The voltmeter in the dash reads around 14v driving during the day, down to maybe 13 or 13.8 at night. The headlights do not dim when this bucking happens.

Daytime I have no problems, it runs like a champ.

Fuel is not the issue, I've already cleaned and checked the entire fuel system, and it still has a mechanical pump.

My father suggested that it could be a dead cell in the battery (optima), was going to have the local auto parts store test batt and alt for me.

Anybody think it could be something more involved?

 

Try this thread. He is having similar trouble. http://www.earlycj5.com/forums/showthread.php?t=51669 Good luck.

 

LIke the other thread I vote grounds. Whatever your voltmeter is attached to has a good ground, your headlights might not have a good ground.