Replaced instrument regulator twice, still have a problem

[Kurt Combs]

My gas, temp and oil pressure recently stopped working. Many years ago I had adjusted the regulator and got the gas gauge to be pretty accurate. After changing the instrument cluster regulator twice, one from LMC and one from NPD, the gas only goes to 3/4, oil is low and temp barely moves and neither of them are adjustable. Both units give the same readings on the gauges, but look to be from different manuactures, so I assume they are working as designed. (LMC had a picture of an adjustable unit, but that is not what they shipped) I can buy a NOS unit for about four times the cost of the other units and I am willing to do that, just wondering if I am missing something like a bad ground wire, or......

[Mach428]

I would first check to see what the reduced voltage is at your gauges. I'm not sure what it supposed to be but I do know it is not 12V. IF the voltage is accurate, your gauges are giving you an accurate reading as well. The fuel gauge reading could be influenced by a bad ground at the sending unit or bad sending unit. You can ground the wire going to the sending unit and your gauge should read full.

Next, I would suspect that the temperature sending unit is problem bad as well and can be checked the same way by grounding.

First things first. I would be spending money replacing VR's in hopes of correcting a problem that is likely somewhere else.

[Mach428]

Sorry, I meant to say that I wouldn't be spending money replacing VR's in hopes of correcting a problem that is likely somewhere else