Help with electrical issue

[rgmrgm]

1983 sc stock daily driver. on occasion has following symptoms:

tach momentarily pegs upon starting almost always.

tach jumps higher than actual RPMs sometimes by 1000 or so rpm other times it pegs not very often maybe one out of ten or more local trips and only after a start up for a couple of minutes then all seems fine.

fan belt screech for 10 to 15 seconds shortly after start up. three or four times in the past month.

always misses slightly for 10 to 15 seconds on start up hot or cold then runs fine.

is this a voltage regulator failing and how do i test it?

[timmy2]

The tachometer jumping sounds like the classic symptoms of the VR or Alt starting to fail.
Use a voltmeter to check your voltage when car is turned off, then at idle, then at 2000 and 3000 rpms.
Should be above 13.2 volts when running. If it is below that then you need to have them tested.
From the description of the fan belt squealing, I would check tension of the belt first.
If the belt is good and the output voltage is low or fluctuating, then it's probably time to pull your Alternator and have it tested professionally.

Steps:
1. Adjust belt tension
2. take voltage measurements
3. either keep on driving if belt tension was the problem or pull alternator and have it repaired.

(Not sure if your car has seperate VR or internal)

[Dave Colangelo]

Make sure your battery ground is on as well as free and clean of any corrosion. I would also clean up all the other grounds in the car just to be safe. Pull them off and sand them all down to clean copper.

Depending on how old the fan belt is, either tension it or replace it. A belt is cheap and dont forget 6 new washers if you are going to replace it. A maybe $20 job is not bad if it solves the problem.

I would also say if you have not changed them, the fuel filter, air filter, spark plugs, distro rotor and cap, and oil/oil filter will most likely take care of the misfire issue. I always do this kind of basic tune if my car starts to run kind of rough with any regularity. 5 years of Porsche DDing and 90% of the time changing these few things has taken care of any misfire or stuttering I had.

Regards
Dave

[Porboynz]

Fan belt squeeling and tach/voltage issues does indicate the alternator is working overtime after start up pumping out lots of amps putting max load on belt. Check voltages as suggested, also do not overlook a faulty battery. The voltage tests will tell you whats going on.

[rgmrgm]

I replaced the voltage regulator with a $35 huco from ebay and voltage output is 14.4 and tach is stable. had to trim a little plastic from the huco to make it fit. damaged the old vr removing it. is there a way to get those things out without damage?