Why is it sparking?

oilleaker1 · Post by **oilleaker1** » Tue Jul 23, 2013 5:52 pm

Just finished installing a 1951 M38 electrical system. The harness is Vintage wiring of Maine. All stock 24 volt system. Thought I'd be careful and check for any dead shorts or leakage problems by testing the main ground lead with the batteries all in place. I noticed a spark with my jumper wire from the neg. ground battery post to the engine stud. This is with the main ground cable disconnected, ignition switch off. All systems off but connected. Once it made the initial spark, I can disconnect the jumper and try again and no spark. I can attach my 12 volt test light, and it doesn't light up. I can make it light by touching the positive post of the battery, so the light is good. If I let it sit and try again with the jumper, it sparks again. So I let it sit and tried the test light-----no light ever.

Is there a capacitor or exciter wire that is causing this? I didn't comb my hair (don't have much anyway) and get static electricity into the equasion.

Wes, anyone, can you tell me what is going on? John

Post by **wesk** » Tue Jul 23, 2013 6:49 pm

There is a capacitor in the stock 25 amp voltage regulator that will spark one time each attempt. If after the spark the test lamp does not illuminate that you have in series between the negative post and the negative terminal then you are good to go.

oilleaker1 · Post by **oilleaker1** » Wed Jul 24, 2013 5:35 am

Thanks Wes, no light, so I'm good. Weeding out a few other issues which I think are no ground due to new paint everywhere. Starter needed the threaded rod for the switch adjusted before it fired up----whew----and then it's a quick re-charging of oil in the gallery and go for the engine start. I don't think this engine or Jeep has moved under it's own power for at least 20 years. Had to go through everything. Found lots of previous bad fixes and straightened them out. Sure am glad to have friends to "lean on" that have practical knowlege. John

Post by **Ryan_Miller** » Wed Jul 24, 2013 8:03 am

A well painted jeep needs to have all grounds cleaned well for good contact - I ran into that too.

If you do have a short, then you will know quickly as 24V burns brightly.