Gages: fuel and temp not working

Adam · Post by **Adam** » Sun Jan 15, 2006 10:19 pm

I've read through the posts and I can see that other truck owners have had problems with the fuel/tempgages. Both of my trucks have fuel and temp gages that do not work or work sporaticly and when they do, they are somtimes inaccurate. I've replaced gages with NOS ones, and sending units only to have the same problems come back. I think I've pinpointed the problem at least with my troubles. The gages in our trucks are thermo-electric as electricity is passed through a small wire wrapped around a thin piece of metal.The wire heats up and bends and the metal moving the needle across the face of the gage (like a bimetalic thermostat coil), more current (less resistance) the farther the gage moves. Inside the fuel gage there is a similar arrangement only instead of a needle there are two contacts, they open and close to limit the voltage going to the fuel and temp gages. Full battery voltage will cause the gage to read maximum (contacts are held shut), with the points open the gages will read empty or cold. The voltage at the back of the temputure gage should fluctuate if the voltage limiter is operating correctly, although mine appears to operate fine untill a certain point and then the points will stick open or shut. Now the question is does any one now how to fix this short of having the fuel gage rebuilt.

JimE · Post by **JimE** » Sun Jan 15, 2006 10:48 pm

As Ed use to say to Johnny on the old Tonight Show " YOU ARE CORRECT SIR". I had to sit down at my computer and put in the manual on cd and read this same info, after I f'ed up 2 fuel guages to figure it out.

As for rebuilding a fuel guage, never heard of it. The voltage limiter is inside the fuel guage that operates both the fuel and temp guages. I am still in the experimental process with the whole wiring thing on my 64. Jim

Jeffc · Post by **Jeffc** » Mon Jan 16, 2006 3:14 am

One thing that you should check if, you are getting readings only part of the time, is make sure your gauge cluster is well grounded. Most of the early to mid 60s trucks did not have a ground wire from the gauge pod to the fire wall and
without the guage pod grounded right you will get readings of the gauges that respond to weak or no ground, regardless of what the sending units tell the gauges.
Grounding of the gauge pod in early trucks used only the screws that hold the pod to the dash, these were often not enough.
Later 60s trucks will have a white wire that is attached to the guage pod near the alt gauge then to the fire wall.

65D100 · Post by **65D100** » Tue Jan 24, 2006 2:41 pm

There are documented remedies for the gauge regulator issues on http://www.slantsix.org

Look under artices and search guages. One modification is to use the gauge regulator out of a 75> instrument cluster still available from year one or your local parts store, a metal relay looking device.

Or if you are handy with electronics there is an article on how to build an entirely electronic regulator circuit to house behind the dash. Both good fixes. My recollection is that the internal fuel gauge regulator can be bypassed to accomodate this.

Before going to any of this trouble, it is a good idea to check and make sure you have a good ground at the firewall and behind the cluster.

Jeffc · Post by **Jeffc** » Wed Jan 25, 2006 11:30 pm

http://members.aol.com/moparnuts/modify.htm
above is link to a updated limiter.
I also have instructions on how to test your fuel gauge
at my photo page below in tech section.
When shops rebuild the truck gauges they can not replace the stock regulator inside the gauge, why? there not made anymore.
What to do if you have one rebuilt?
make the above or buy a limiter from a car set that are still made and wire it in to the 12volt side of the gauge before it enters the gauge.
The gauges can be rebuilt, just without the regulator.