Electrical Issues - Problems Starting

[hdaemon]

I'm having a bit of a strange electrical problem. While out yesterday, my car ('90 535) refused to start. It had started up fine when I left home, but upon trying to return, wouldn't do anything. There was enough power to trigger the locks when I first got to the car, but as soon as I tried to turn it over, it wouldn't do anything. No locks, dash lights, dome light, etc. Started immediately with a jump pack, and drove it home. After stopping, would not start again on its own.

Disconnecting and reconnecting the negative terminal was enough to get me accessory functions back, but the moment I tried to turn it over, everything went dead again. When I brought the battery in and hooked it up to the charger, the charger claimed it was full. Didn't leave it connected for more than a few minutes.

This is actually the second time this has happened to me (suddenly refusing to start/do anything). It happened about 18 months ago, and at the time, I ended up replacing the battery. On a whim this evening though, I put the battery back in the car, and suddenly it's willing to start right up again.

Any suggestions for where I ought to start looking for problems? When I checked the current with the car off, I was getting about 125mA, so there's probably something drawing it down, but I don't think that would explain this behavior.

Any suggestions on what could be causing this? Seems like something is shorting out when I turn it to start, temporarily drawing the battery down, and preventing the starter from turning over. The starter is probably fine, because it's always started immediately when being jumped.

[pingu]

Fusible link?

[whiskychaser]

Engine earth strap? Check by connecting heavy duty jump lead between a good earth point on body and engine block

[Ferret]

I'd have to suspect a connector/fusible link here somewhere.

It's showing classical signs of burning out something somewhere - the starter draws enough current to fry a dodgy link somewhere.

Try cleaning your battery contacts with a file and the inside of the clamps with a circular file first.

Where are you jumping the car from, the jump point up front or the battery terminals?

Next time it does it, try jumping it from the battery terminals themselves and see what happens.

[Ross]

It started with the old battery?
Sounds like the new battery is dead, probably just not being charged by the alternator. There should be over 13 volts while the car is running, if not suspect the alternator. Most of the time replacing the internal voltage regulator does the trick.

[hdaemon]

It started with the battery that had been in it (and had refused to start with a day earlier). The battery that I replaced a year ago got returned for the core deposit.

It started with the old battery?
Sounds like the new battery is dead, probably just not being charged by the alternator. There should be over 13 volts while the car is running, if not suspect the alternator. Most of the time replacing the internal voltage regulator does the trick.

[hdaemon]

I'd agree, except that if the battery were frying a link somewhere, I would expect that it would do it once and then nothing. Fuses don't generally go about repairing themselves. So unless there's a resettable breaker somewhere...

I'd have to suspect a connector/fusible link here somewhere.

It's showing classical signs of burning out something somewhere - the starter draws enough current to fry a dodgy link somewhere.

Try cleaning your battery contacts with a file and the inside of the clamps with a circular file first.

Where are you jumping the car from, the jump point up front or the battery terminals?

Next time it does it, try jumping it from the battery terminals themselves and see what happens.