Ok, well the past few days I'd been having different problems with my truck not starting, first with the manual fuel pump going out, which I fixed. Then, the starter burned out, after working perfectly fine.

So.. now for the questions:

I'm running two batteries w/ an isolator, and a switch in the cab that I wired up a while back, so that if I hit the switch, it runs them in a way that it adds the amps of the two together, without adding the voltage.. but I've heard that if things get wired wrong, it will keep the same amperage, but add the voltage together.
Right before I came in for the night, I took the negative cables off both batteries, and put a volt meter from the positive on bat. 1 to the negative on bat. 2, and it was reading voltage. The switch in the cab was off.. this makes me think that the diodes or whatever in the isolator burned out, and are no longer keeping the batteries seperate. If that happened, would it be possible for the batteries to be changed from the normal configuration to that of a series (I think that's the term) where the voltage would be added together, and therefore burning out my starters? I can't think of anything else that could be causing it.. I pulled the newly installed starter that had been working 5 min before I put it in, and then went to the starter solonoid and jumped it w/ a strand of wire. And being 10PM it was quite dark and I could instantly see the battery terminal wires getting red hot. Any help I can get would be greatly appreciated. I'm tryin' to get it runnin' again for an offroading excursion this weekend, and I'm at my wits end. If you need any more info I'll gladly check things out and report back.

Thanks,
Levi

 

What type of isolator do you have? Is this just like a starter relay that is turned on and off by a switch inside the cab? Or is it a big heatsink with some diodes in it?


You where jumping the new starter to the battery with a small wire? And the small wire got hot? If so, you need to do your starter testing with a large jumper cable. The starter draws lots of current, which a small regular wire can't handle.

So the point you are at right now is, you can't get the truck to crank over correct? And you installed a new starter and it still will not crank? Will it even click? Do your headlights and radio still work inside?

 

I've got an isolator hooked up, the kind that's a big heatsink w/ diodes in it. Which is to keep it from drawing power from the 2nd battery, and still charge both of them. And then a starter solenoid that I used to connect them via the in cab switch to help start the truck if something happened to the first battery, like leaving lights on too long w/ truck off or something like that.


When I pulled the starter and tested it, I left the big terminal wire connected to it, and kept it grounded via the bolts. But it was pulled out enough that it's teeth wouldn't be touching the flywheel, so I would know that it's not turning due to being jammed. Then I jumped the starter solenoid, the one that would get power when the key is in the start position. And the cable that connects from the solenoid to the positive on the battery 1 started turning red, right where it connected to the solenoid.

Headlights turn on. I've got the radio pulled out right now. This is just my offroad vehicle that I play around with. The starter relay does click. And it doesn't keep clicking like it would with a low battery, it clicks once when I put the key in the start position, and then again as I turn to key back to the on position




Maybe it would help if I told the whole series of events.. I'd been working on it for the past few days, troubleshooting several problems, w/ the fuel system/batteries/starter etc.

I got it to turn over using the new starter night before last. But it was only running on gas that I had primed the carb w/ because I had not replaced the fuel pump yet. I exchanged the 2nd battery at Autozone that day, so before I went in for the day, I hooked up the battery terminals to the 2nd batter and went to bed. Next day, I put in the new fuel pump, and then when I put the key in the on position, I hear the starter solenoid/relay click once, and then as I take it off the on position it clicks a second time. That all sounds normal to me. like it's working correctly. Except for the fact that the starter itself isn't turning of course. Then I went to the engine compartment, and jumped the connections on the starter solenoid, baisically doing the as turning the key to the on position in the cab, just where I could hear what was going on better, and I noticed the battery terminal cable that goes from Bat1 positive to the starter relay getting red hot.

The Isolator I have is only a 95 AMP isolator, I believe. I'm just running the stock alternator right now, which I believe is 85 amps or so. But, I heard that it's 85 amps@~2KRPM or so. And w/ my gearing/tranny I see around 4KRPM just to hit 65/70MPH, so I'm wondering if it could have induced the alternator into producing higher than 85 amps, burning out one of the diodes in the isolator, mainly the diode for bat 1 to where electricity could flow both ways.

I believe my first step today is going to be to pull the isolator and second battery out. And see if it turns the starter like that, if not I'll take it to autozone and have them test it. If it is fried, I'll try exchanging it for a new one and see if it gets fried now that there will only be the one battery in it.

 

It sounds like the new starter has a problem. I would take it back and exchange it.

 

Well, ends up that, the starter wasn't getting grounded. I ran a battery terminal cable from the the bolt that holds the neg from the battery to the frame, to one of the bolts that hold the starter to the bellhousing.
Then, I ripped out all the wiring for teh charging system, and rewired it to only use the one battery, and it charged it up correctly. Then I wired up the isolator, and the second battery, and it didn't get charged while the first one did, so I think it's bad, and I just set it back up to using only one battery.