Ok, working on a '69 w/302 and 4 barrel edelbrock carb and factory air. Problem I'm having is with a few of the gauges on the dash, mostly the fuel gauge, it reads about half a tank low. Second problem is with the alternator gauge, it doesn't read anything at all. Third problem is minor, but the oil pressure gauge seems to read a bit low too.

Now as far as the fuel gauge issue, would that be problems with voltage to the gauge, a bad sending unit (I think is what it's called), or something else? And I'm assuming something is disconnected somewhere as far as the alternator gauge. Oil gauge I wouldn't know where to start.

I have the shop manuals, but I'm a bit unsure where to look, so I'm asking here first and in the mean time will try and find anything in those.

 

The printed circuit board in 1969 Mustangs is notorious for problems. Most of the solutions I've heard about is a poor ground of the circuit board. There is also the connector that has the potential for poor contacts. If this is confusing you, there is the constant voltage unit that provides 5VDC to the fuel, oil pressure and temperature guages. To replace the constant voltage regulator (it's mounted to the back of the instrument cluster) you need to remove the instrument cluster. Remove and reinsert the connector several times. This might clean up any crud build-up. Unfortunately, I do know of a way to add a ground but I would recomend looking at the bracing behind the instrument cluster for a small screw with several (maybe only one of two) black wires going to it and tightening it.
Jim

 

As far as the guage,,,, the float may not be floating,,,,, could be filled with fuel or saturated if it is the solid type float.

Might want to make sure before chasing electrical gremlins.....