Thr voltage limiter or IVR (instrument voltage regulator) is inside the gas gage on a rallye dash. You can do 3 things, replace the gas gage with another used one, buy a repop one, or dissassemble the face off yours, dewire the voltage regulator part leaving the gage side intact and piggyback a homemade solid state regulator onto the back side of the instrument cluster. Much easier to do than it sounds.
Your temp, oil psi, and fuel are all tied to the IVR which drops 12v to 5.5V to run those gages so if the IVR was acting up and sticking open they would all be at their lowest settings, if it stuck closed they would all go to their highest settings and would all do this at the same time.
I suspect you have several issues going on. None of which are related to the IVR. I suspect a fuel gage sender short to ground as well. And the other 2 for oil pressure and temp are their own issues. Maybe the wiring is not connected to the senders, possible bad senders, possible broken wire internally. With these 2 an easy test will confirm the wire is ok. Jump the oil psi and temp sending unit wires straight to ground and turn the ignition key on. If those 2 gages go to the high end then the wiring is good and the senders are likely bad.
Ammeter typically stays in the middle and just moves based on charge or discharge load. I recommend doing an ammeter bypass, convert the gage to volts an be done with it.
Theres plenty of threads on bypassing the ammeter and bulkhead. I will post my schematics for this. Some people prefer to wire it differently. Theres other threads on here about converting ammeter to volts and what aftermarket voltage gage to use to do it. I used a 2" sunpro CP8215 volt gage for the guts to convert mine. They sell this gage as a white faced gage and a black faced one. Either one can be used since you will only be using the internal movement plastic grommets nuts n washers and throwing the rest away.
1st pic, how its currently wired as stock
2nd pic, the ammeter bypass
3rd pic, homemade solid state IVR
4th pic dewiring the gas gage, and what to leave intact
5th pic solid state IVR. Shown with spades. One for rallye cluster uses ring terminals
6th pic, how to jumper in the volt gage
7th pic wiring in the Piggybacked solid state IVR
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