Voltage fluctuates with rpm of motor.

[Lamb]

Please help me figure this out. I have a 1990 saleen with an up graded alt; new battery. The violtage in my car fluctuates with the rpms as does the brightness of my headlights etc. This is a particularly annoying situation since my fuel pump is directly wired to the coil and it makes for a difficult time tuning the vehicle. If anyone knows an answer to this situation I would greatly appreciate some enlightenment.

 

[HISSIN50]

More info is needed. What flavor of upgraded alternator do you have? What is the differential in system voltage, etc.

At idle when the alt output sounds to be dipping, the demand on the FP is minimal, so 'performance' should not be seriously affected. Something along the lines of a component booster (B-A-P, etc) can help with the situation, if there is one.

Anyhow, more info please.

Good luck.

 

[MikeC]

Do you have underdrive pulleys?

 

[tbovee]

I agree with everyone above. More info. But you could always check all of your grounds first,

 

[sjhm9102]

slipping belt or you need a new alternator

 

[Daggar]

Things that come to mind with available info so far:

Field wire connected to improper location
Bad regulator
Bad regulator diode (will usually manifest itself with a dead battery after sitting over night)