I've been having some electrical issues on my pulling truck. Just wanted to throw the problem out there and see if anyone has ever had a problem like this or something similar to this happen and what the solution was.

Problem: When you crank the truck over to start it, the tach needle will jump around like crazy, and it may or may not backfire out of the carburetor. Once it starts it runs rough and sometimes pops out of the exhaust. If you crank it over and the tach does not jump around, it will start up and run just fine. Basically, the truck runs different each time you start it.

Solutions: So far, we have changed the distributor from a Mallory to a MSD Billet. We have torn out all of the factory wiring and wired in a Moroso switch panel that has five toggle switches and a push button for the starter. This obviously eliminated alot of unneeded wiring, but it did not solve the problem. I have two new, fully charged batteries. I am running a MSD Billet Distributor, MSD 6AL, and MSD Blaster II coil. I'm probably going to try a different coil and rev chip next.

Anyone have any ideas on what to check first, or has anyone ever had anything like this happen to them before.

 

You have a loose or dirty ground somewhere in the ignition system. Add new straps from everything in the ignition system to ground.

 

Thanks for the info Bear....I will double check my grounds....Again. I am also going to add a new ground cable from the block to the frame.

My battery is 975 CCA. Could it possible be that I need to run a larger battery?? Like I said, I keep it fully charged. I've also tried my backup battery to no avail.
Is everyone in consensus on this or did someone have a different idea. I'm puzzled and frustrated. Any help is appreciated.

 

Battery size is always an issue. Try putting the back up battery on with the primary battery with jumper cables. If the problem goes away, that will tell you if it is a battery issue.

 

Did you try disconnecting the tach ?

 

Yeah, I disconnected the green wire from the MSD Box right as it was acting up, but it didn't change the way it was running.

 

Sounds like your coil may be on the blink, especially since it connects to the tach.