Volt gauge started acting funny won't stay running.

I just got done doing an opti, waterpump msd coil and wires, car ran great for over a week...

Last week while I was driving it started to almost die while cruising, that's when I look down and see 0 volts, so I take it home, go out to start it and my volts are good, next day 0 then it popped up into normal now I have 0 and car will fire right up and die right away, also it wouldn't crank when I had jumpers hooked up for 10 mins but did and ran great 20 minutes later and ran good for about a minute then my idle kept dropping up and down then it died, now if you try to start it, it will fire up and die right away.

The kicker? Both the alt and battery tested good, connections are tight and not corroided.

Any idea's?

Thanks alot, I'm stumped - volt regulater? Idk need help.

replace the alt. could be starting to die.

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Originally Posted by WS6ix

replace the alt. could be starting to die.

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^^X2. Most likely the alt is on it's last leg.

He said the alt tested good.

I'd start with grounds - especially the ones by the MSD coil that you were just playing with. ;) The grounds are held on with a nut - after a few heat cycles the nut could've started vibrating loose and causing a bad ground.

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Originally Posted by meissen

He said the alt tested good.

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True, but it can and still probably is going bad. I've tested many Alternators in my earlier days and it's about 50/50. Being that his problem is intermittent (plus the VR is built into the Alternator), the test performed could have been done while it was functioning properly.

i tested alternators befor and they were good but they were pooched. half the diods or whatever they are called in the unit can be good and the others bad. all depends on the dumb thing.....thats why i hate electrical way to temperamental.

but also trace the wires and look for faults. thats the cheap way and sometimes can be the culpret but my guess is the alternator. buy a new unit try it if it dont work return it just dont beat the crap out of the case so they cant tell its been installed. :D