Is there an instrument voltage regulator that controls the gas, oil, voltage, and water temp gauges on the 91 RS with 305 TBI? I'm getting readings outside the normal ranges on all gauges. The oil press and water temp show readings a lot lower than they should. The voltmeter is higher and the gas gauge moves around a lot from E to 1/4 tank.

 

To my knowledge, they are all designed to work at normal system voltage (14.1VDC). There is likely a regulator for digital dashes, but the analog gauges are rather simple.

 

i too have asked that very same question about the gauges and have read some varying answers. The most common is that the analog guages on our cars just get old.

The gas gauge is most acurrate at full or around 1/4 of a tank, they tend to stick in the middle aparently and from personal experience will go from 3/4 to 1/4 from one startup to the next without traveling far and maintaining a steady average mpg rating.

The oil gauge will read low, most of our cars have lower than should be oil pressure (again I took this from multiple posts) and should be around or a little below 40 when idling and between 40 and 60 when cruising (mine falls a little below from time to time but for the most part stays decent)

As for the voltage gauge mine on occasion will fall below 12 when idling, but the previous owner put an underdrive pulley onto it so that could be, but at other times it goes above, looks like it read 15 or so, but when I test the alt it checks out fine.

I dont know what this can do for you, but if you think there is a serious problem then look into it, otherwise it could just be that the car is acting the way it should being how old it is. Or the gauges could just be faulty and gm didnt think it was bad enough to do something about.

 

My oil pressure gauge is always above 60 psi at idle or crusing speeds. When I shut the car off it will travel back down. What could cause this?

 

im guessing u have way too much oil in your car, a bad sending unit, or the spring that controls the needle is bad