View Full Version : Diagnosing generator/regulator issues after electrical fire

September 22nd, 2013, 03:00 AM
I had a small electrical fire in the 62 today...

I shut the engine off and heard some sizzling. It was the wires to the ammeter mounted under the dash. I disconnected the battery before it spread... WHEW!:ahhhh:

The little hose to the oil pressure gauge next to it melted and it really started smoking!

So I poked around and saw that both wires to the ammeter were fried and so was the ground wire from the generator to the voltage regulator mounting bolt.
The previous owner spliced into the wire from the"bat" terminal on the voltage regulator to the ammeter, and then back from the ammeter to the starter... and didn't use a fuse!:noway:
It is hard to tell exactly what happened but I do have some clues:

The burned wire stops where he spliced it near the starter. The rest of that wire appears fine(from the starter to the "bat" terminal of the ignition switch I'm thinking?).

The middle contact in the voltage regulator barely opens(I mean a frogs hair). The inside of the voltage regulator doesn't smell burned in any way though....

At idle the "gen" idiot light wouldn't completely go out and the ammeter would read 0 or just above 0. Give it gas and it would move though.

There has been a faint grinding noise under the hood from the same side as the generator. I didn't think it was the generator though since it has been working fine...

I can fix the wiring easy enough. I am afraid of something in the generator or the voltage regulator being a problem? I also forgot to polarize it when I put the battery in a couple weeks ago. Could that cause the wires to melt?
Is there a way to test these components individually?
Do ammeters fail and cause these problems? If I dare hook it up again it will be with a 30 amp fuse!

September 22nd, 2013, 07:35 PM
My 2 spare motors came with a lotta spare parts, including a generator and an alternator.When I first got them I held the alternator and upper bracket up to the block and it didn't seem like it went to these motors. I thought the only lower bracket was for a generator.
Since I need to do some wiring I decided to upgrade to an alternator. The one that came with the motors was externally regulated. Not what I want but it is what came on these motors so I took a closer look. The lower mount was bolted to one of the engines!:headscratch:
I dunno how I missed that but good for me!

Then I peeked under the hood of my 63 Chevy...

It had a 10si!:yeeuh:

Now I just need some hardware, a belt, and some time with a soldering gun and I will be set!

September 23rd, 2013, 06:08 PM
:ahhhh: That was kinda scary Tommy!

I wish I had info on generators to give you a hand. I kinda like the idea of using one, but my truck came with a 17SI that I just rebuilt so I never got to play with a generator.

Fun fact: You can remove a battery from a generator truck and it'll still run! You can't do that with an alternator. Great for battery sharing if you're too cheap to buy two. You'll like the 10SI though. They're troublefree and easy as pie to rebuild for about 16 bucks!

September 23rd, 2013, 06:24 PM
I ran a later model Jeep without a battery. It wouldn't idle (I think because of the TPS sensor) but it ran fine for a few minutes with my foot on the gas... I have since been told that is a no no.:noway:
The 10si should be fine but I eventually have to put something back in the other truck so I might as well get a 12si for this one since it is wired the same. I want to do a little modernizing while I'm at it... relays for the headlights, fusible links, etc...

...and removal of the evil ammeter. I'm reasonably sure that the fire started there:tongueGMC: