Power cut out then on again

A30_John · Post by **A30_John** » Thu Jun 21, 2007 11:50 pm

This evening I commissioned my engine following my Spring launch. While I was running the engine, I glanced over and noticed the instruments weren't working. Not knowing what was going on, I shut down the engine. I tried turning on the radio - no power. Nothing on the house side worked. The bilge pump, which is direct wired (not through main switch) worked. I tried wiggling wires to see if I could identify a loose connection into or out of the main switch and panel. No luck.

About 10 minutes later I tried again just for the heck of it and everything worked. I restarted the engine and everything worked fine. When I left the boat later this evening everything was still working.

Does anyone have any idea what could have caused this to happen? I worried that I might get a nasty surprise some day when I least need it.

Thanks.

Ceasar Choppy · Post by **Ceasar Choppy** » Fri Jun 22, 2007 8:28 am

Sounds like a bad ground connection.

When everything starts acting wierd, its usually the ground. :) I'd check the connection on your main ground (is it grounded to the engine?).

A30_John · Post by **A30_John** » Fri Jun 22, 2007 8:51 am

Yes it is. I'll check it carefully. Thanks for the suggestion.

It was nice to see that the engine kept running apparently without use of the fuel lift pump.

Ceasar Choppy · Post by **Ceasar Choppy** » Fri Jun 22, 2007 10:11 am

Also check negative connection on the batteries. This happened to me one time and while everything worked, the loose connection of the neg on the battery prevented the charger from charging, and somehow the alternator got fried (could have been a separate incident).

The upshot was, I was stuck out on the water and I got to use the handcrank on the A4. Worked like a charm!

A30_John · Post by **A30_John** » Fri Jun 22, 2007 11:04 am

The battery connections are definitely good.

I'm going to inspect the ground connection very carefully this afternoon.

Quetzalsailor · Post by **Quetzalsailor** » Fri Jun 22, 2007 12:46 pm

Have you got a breaker on some major portion of the wiring? (My 1953 Studebaker had a breaker on the headlight circuit, and I think, glass fuses on everything else. The insulation burned through because I did not tie my new wires up away from the tailpipe adequately; it took quite some troubleshooting to understand why the lights kept going off and coming back on! The breaker was a simple bimatallic strip with contacts and made or broke the connection, unlike the breakers in your basement.)

One of my favorite loose connections was a broken wire on one of the A4's Delco alternator's diodes. Installing and tightening the connections on the alternator spun the stud enough to break the wire. Once found, I dispaired of soldering so close to the diode and I simply stuffed it back together with the broken ends touching, intending to get the reinstallation of the rebuilt engine done and operational and replace the offending bit later. I never did replace the bit and sold the boat several years later.

A30_John · Post by **A30_John** » Fri Jun 22, 2007 2:41 pm

I was not able to locate one. If there is one, I'm not sure how it reset itself. That's the curious part of this problem-it "fixed itself" and I can't repeat the problem. Which probably means something is loose, and, as Ceasar suggests, it's consistent with a grounding fault. I'm on my way out to the boat now. Let's see what happens today. :-)