91 Euro Alternator issues

[wolf1477]

Hello all,
91 Lumina 2 dr Euro sport. Changed the alternator and now the stupid thing won't start most times and when it does it runs fer crap (stalls, etc etc). So far the only way we've gotten it to start is hit the key and the gas at the same time and rev 'er up a bit then it'll drop into a solid idle, but, try to go anywhere and she'll die in an instant.

Took the pos cable off the battery before removing alt/cabling. Hooked everything up before reattaching the battery. All connections look solid.

Any ideas?

Thanks

[jeffcoslacker]

It has to relearn it's idle stategy. You can just drive it, and it will recover, eventually. You can set the e-brake and block the wheels, and just let it sit and idle in gear until the radiator fan comes on (usually 10-20 mins), then it should be reset.

[jeffcoslacker]

It may take a few tries to get it to idle in gear. If it refuses, help it with the throttle, and slowly back out of it until it is idling on it's own. (in gear)

Usually when this happens, they idle way up and down, surging because they are hunting for the proper idle mixture and speed, because the ECM constantly makes adjustments based on the motor's current state of tune, but all that memory is lost when the battery is disconnected for more than a few minutes.

[wolf1477]

Ahh, thanks much. I'm also curious, is the new alt supposed to get hot (as in can't touch it)? You'll have to forgive me, I'm used to working on SB350s and such, these sideways 6s just are a whole nuther animal.

Thanks again,

[jeffcoslacker]

They do run hot, 100 amps in a very compact unit, that was part of the reason for longevity problems with the original units. The reman unit usually have larger bearings to help cope. How long does it take to get that hot? Any whine or whirring from it? Is the harness going to it getting abnormally hot? Sometimes a reman will have a bad regulator, and it sticks full output until it burns itself out. Some will run hot at first until "broken in" for lack of a better description, but calm down after they've been run a while. Keep an eye on it.

Make sure your harness doesn't have any cooked wires, seen posts where a couple of people had real bad problems with charging and whacky idle/performance problems after an alternator change, and find a reference wire to the ECM that was burnt, causing multiple problems.

[wolf1477]

Hello,
Yeah the wires all look fine. Felt along 'em to see if there was any charring/thinning. The alt itself just seems to get very hot very quickly, the harness stays roughly the same as it always has (granted I think it's picking up some heat from the alt). I'm going to throw a different alt in (Had many problems with Autozone alts before so will try a different one just to be on the safe side.

Thanks for the help, it's appreciated

Sam

[jeffcoslacker]

No longer buy any reman from AZ, too much problems with them. Really, on those early 90's GM alternator, the Delco remans are the only ones we never had any problems with.


Put one in a car like yours once, as soon as the engine started it screeched like a banshee, and threw sparks outta the case like a circular saw cutting metal.

Another one came back on a tow truck, with the alternator's front bearing that got so hot, it melted the case and the belt tension pulled the shaft down through it like butter before the belt finally melted and broke.

I've seen some weird stuff.

[wolf1477]

Heh yep, I shoulda known better than going to Auto Zone, but, it's close to home (and close counts when one's walking), I went and took the first back, had 'em throw the second on the tester...BAD. Got my money back, went to Bumper to Bumper and bought something I could trust. Works great so far...doesn't even get hot!