A couple of problems with the Lil Duke Coupe

[Fierofool]

Problem  1:  Returning from the club meeting, he car began to shut off.  Turning the ignition off would allow it to restart.  Left the car sitting until last week when I took it to Don's.  It drove fine without problems for the 75 miles.  He put another 170 on it without problems. 

Returning home with it, I made it to within 1 mile of the house when it started shutting down again.  Trying to bump start it or using the starter wouldn't work.  It would only start after turning off the ignition.  It shut down 3 times in about 200 yards.  Finally I drove it the rest of the mile home without problem.

Problem 2:  Tonight when returning from my daughter's house, I noticed the headlights pulsate line a motorcycle headlight.  It has a new alternator and battery.  They don't pulsate at idle speed, but anything above 1500 rpm they start pulsating. 

Any ideas? 

[Roger]

Sacrifice a chicken and have garlic hung around the car.

Or, when you replaced the alternator did you hook up the Sense wire at the alternator?
That would be the 'D' wire in the 4-pin connector on the alt.
You can take it straight to the B+ terminal on the alternator. It doesn't have to be a heavy gauge
wire because it is only a 'sense' wire. It will more readily tell the voltage regulator that
it has to keep up with the increased power demand.
This is assuming that there is nothing wrong with the alternator, voltage regulator or an intermittant ground.

Whoever heard of an intermittant ground in a Fiero anyway?

These newer alternators have a 'low' and 'high' charge rate. They don't vary like the older Delcotron.
The ignition system puts a lot of drain on the battery at high RPM (as opposed to lower RPM) so the VR jumps
from 'charging' to 'forget it' and back, hence the pulsation.

If the ECM input voltage drops below 10.5 volts, that may be why the car shuts down. Turning off the ignition
resets the uP to square 1.

[Fierofool]

The alternator seems to be charging very well.  The lights are very bright, not dim.  They pulse brighter instead of dimmer.  Would your information still apply?  There was no jumper wire on the old setup.

The Garlic and Chicken didn't work so we had it for dinner last night.

[jwrape]

It almost sounds like a bad ground.
I don't have experience on the Fiero in this way but I used to have a pulsating headlight issue with my 91' Mustang GT and it ended up being a bad ground. I just ran a large cable from the Negative terminal over to the block and grounded it. Seemed to take care of the pulsating.
Not saying that's the exact correct way to fix the issue, the right way would be to check your factory grounds and find the culprit, but an extra ground never hurts anyways.

I also used to own a 87' Chrysler Conquest Tsi that had 11 grounds throughout the car and the car was KNOWN for having grounding issues. The Forums always suggested making note of grounding locations and make sure you check them to be properly grounded so the car would run at it's best. But then again, that car was a maintenance hound. It always had issues, even after I had rebuild the entire motor to new including sensors etc. it still had issues....

My 2 cents is to always check your grounds when having pulsating or glitchy issues.

[Fierofool]

I ran a voltage test on it this afternoon.  At idle, the alternator is putting out 14.15 Volts.  At anything over idle the lights and instrument panel start pulsing.  The alternator puts out 15.25 Volts in this condition. 

I haven't done anything on the stalling problem, but plan to replace the ignition coil to see if it's breaking down when it gets hot. 

[Roger]

Sounds like too much wiper fluid in the tires.

You should have no more output than 14.5 volts.
There should be no less than 13.5 volts.
Anything else points to a bad voltage regulator...even if it's new.
Sometimes they good on a test bench and then bad in the car.
That points to a short in the cars electrical system.
Sometimes they show good on the bench and when on the car,
after heating up or being subected to heat, they go bad.
Ain't electronics fun?
Which type alternator do you have?

[85GT]

charlie, the last alternator i bought at " advance " put out to much volts also, i took it back they put it on there tester and it was putting out 16 volts. they replaced it and i had no problems since....

[Fierofool]

This one isn't returnable.  I bought it from Pat who got it on Ebay. 

Roger, I don't know what alternator it is.  It's just the small one for the 88 Duke.  With that kind of output I'm afraid I'll kill that new battery, but man, I can say these lights outshine the best of the high output varieties found on the ricers. 

[85GT]

I have a new regulator, you can have if it,s the same, it's a 94 amp.. I'll bring it to the meeting, if its raining we can change it out inside, only takes a few minutes.... Jerry

[Roger]

It'll be an SI or CS model. The SI has a 2 pin plug. The CS has a 4 pin plug.

Sounds like 85GT has you fixed up.
Bring 2 paper clips to hold the brushes in.

Good thing you played it safe. They will cook a battery!

I'd love to be there rain or shine but I'll be in FL.

[Fierofool]

The alternator's installed in the car.  I guess I could put it into the old alternator.  I just checked the old one and it's 4 pin.  I doubt it's any good, though because it's full of trash from sitting so many years. 

I'll just wait until my back gets better and the weather's suitable and change it out. 

[Roger]

If its just full of trash blasting it as clean as possible with the water hose should do the trick.
As long as it spins without making a screeching noise ;-P

I suppose the old one is truely bad?

[Fierofool]

Yes, the old one is the one full of trash.  It wasn't charging very well so I replaced it.  It may be serviceable with a regulator replacement, though.