WEIRD electrical problem - help, please!

[peejay4A]

I should learn to read the thread more carefully. I guess it should be straightforward enough to check by carefully disconnecting the thick cable to the starter, at the solenoid end, while the engine is running and see if normality returns.

 

Proceed with care though because if this is the problem then arcing is a real possibility.

 

Or disconnect the starter and bump start.

Edited August 5, 2014 by peejay4A

[JayeM]

Thanks for the continuing help, all - it will be Thursday before I can get back to the car, so fuller update to your suggestions then.

 

Meanwhile, some clearing of your suggested red herrings, I think.......

 

1/ My AVO cutout has disintegrated inside (the little rocker arm with the contacts has broken up) so the AVO pop could well be coincidence.

2/ The alternator regulator is fried (short circuit both ways)

3/ my DVM misbehaved on some ac volts checks I was doing, so it's now suspect.

4/ the starter isn't running after the engine starts, and there's no current going to it when the engine's running.

5/ one of the new coils isn't labelled, so it is possible it's a ballasted coil instead of the correct 12v one.

 

So I'm hoping that a checked new 12v coil, new alternator regulator, and a different meter might find the problem has actually been a simple one ( a dead alternator regulator) confused by a lot of coincidental happenings!

 

We'll see on Thursday. I'll also take on board your sensible suggestions of checking all the feed wiring and changing the ignition switch for a spare.

 

Thanks again,

John

[Paul Down]

Perhaps I misunderstood but you mentioned in your first post that the alternator had already been changed for a new item but that the fault remained, does this mean that you have actually fried two regulators? Or that when you replaced the alternator you used the original faulty regulator?

 

If you have fried two regulators there is obviously something very amiss with the wiring.

[MikeF]

Earth connections are 90% of all electrical problems and a duff earth could give you an in series alternator as suggested. Is engine earthed to chassis and or battery? Jury rigging a separate circuit would show intermittencies and poor earth etc. You could probably use your charger as an isolated power source

I have a moving coil/analogue multimeter from Maplins which cost me about 7 quid a few years back. Its slightly annoying in that its low volt ranges are badly chosen for car work, but you can drive over it OK. I remember it wasn't prominently displayed n the geek zone at the back of the shop, unlike the expensive digital jobbies!

 

 

Mike