1952-59 Ford Faulty gauges on 59’

Looking for advice. I’ve got a 59 Ranchero with faulty gauge readings (also have auxiliary gauges that work fine).

I have new senders (fuel & temp) and the voltage regulator is about 12 years old but the car sat indoors / unused for 10 years. The (NOS) temp gauge goes straight to overheat when key is turned on, so I disconnected it. The fuel gauge works but travels down to empty very quickly, reads 1/4 tank after 20 miles. Fuel consumption is not the culprit.

Does that sound like a bad instrument cluster voltage regulator? How do I test the regulator? Is it simple as checking 5-7 volt output?

 

Sounds like a bad ground to me

 

I guess I’ll make sure the VR itself is grounded. I’ve already run a solid independent ground throughout the whole car. Thanks.

 

The gauges are a bi-metallic strip with a heater element that is fed current from the gauge regulator. It takes a little time for the bi-metallic strip to move as it is heated so it does not require a constant current but an average current if that makes sense. So, 12 volts that is on 50% of the time and off 50% = an average voltage of 6 volts, that is how the gauge regulator works. It should have a pulsing output, if you put a test light on the + side it should be on all the time. The output side should pulse or flicker. This gauge regulator needs to have the case grounded to metal with good contact to work as you said. The temp gauge going quickly to hot sounds like the wire to the sending unit is grounded somewhere or the sending unit itself is grounded. Mark

 

Replace this first. https://www.ebay.com/itm/193835820182 This may help also. https://www.tanksinc.com/index.cfm/page/ptype=results/category_id=159/mode=cat/cat159.htm

 

@nosford ok so that explains the special meter I read about. I won’t see a plainly reduced voltage it should fluctuate- or the test light should blink.

@JeffB2 thanks for the info. I’d like to troubleshoot a bit further before I replace anything. Gonna

I’m gonna start by pulling the instrument cluster and check function of the VR. I don’t suspect any wiring issues because everything is new and carefully routed but I will certainly look it over this weekend.

 

When converting to 12 volts the CVR from early Mustangs is commonly used (same as your '59) This video shows how to do the test.