Testing a gas gauge

[17remfan]

Is there a way to test a gas gauge in the car to tell if if a bad gauge or maybe the sender unit in the tank.same thing with the temp gauge . They both sem to be hooked up but no function .

 

[kocuda]

Fuel gauge: unhook the wire at the tank, use a jumper wire and ground the wire, with ignition on the gauge should read FULL, if not problem is in wiring between gauge or the gauge. Same thing to do with temp gauge.

 

[17remfan]

hey, thank you so much .That will be very helpful to me .

 

[kocuda]

Forgot to mention, if after doing what I suggested and gauge works, before you condem the tank sending unit make sure you have a good ground to the tank and sending unit. Ive seen many gauges not work because the ground at the tank unit was faulty.

 

[1968FormulaS340]

Multiple gauge failure is often the gauge voltage regulator. The car runs off 12 volts but the regulator steps it down to 5 volts for the gauges...

Depending on the car the dash regulator will....

1.. Be on the back of the cluster. (this is replaceable and the part can be had from any auto parts store)

2.. Internal to the fuel gauge (Like on my 68)

If it is in the fuel gauge you will need to replace the fuel gauge or disable the internal regulator (requires you to remove and open the fuel gauge) then modify the gauge power supply using a 5 volt regulator from Radio Shack or others...

 

[RedFish]

when more than one or all gauges are dead the common factor is the instrument voltage limiter than supplys their power. Good luck

 

[IntenseNeon]

I have a similar problem, my gas gauge goes to full when the key is on and the temp gauge doesn't work, and i've checked the grounds and connections out. As I understand it If I get one of those voltage regulators that you sell Redfish I should be good to go?.

 

[mullinax95]

Forgot to mention, if after doing what I suggested and gauge works, before you condem the tank sending unit make sure you have a good ground to the tank and sending unit. Ive seen many gauges not work because the ground at the tank unit was faulty.

This is very true. I took my gas tank out to change the sending unit and clean everything up. I noticed that the previous owner had a homemade ground form the tank to the car's frame. When I installed my tank back in I didn't hook that ground up just to see if the gauge would work without it... well it didn't work. I hooked the ground up, turned the switch on and it worked. :-D

 

[ram250098]

I just fixed mine a few hours ago. After checking wires for power and grounding gauge etc etc all it ended up being is the two nuts on the back of the printed panel were loose. I just snugged them up with a 3/8 socket and it worked fine. I think the temp gauge gets it's power from the gas gauge, I could be wrong but I did read that somewhere.
Sometimes it is the most simple things that work LOL
AL

 

[1969GTS]

when more than one or all gauges are dead the common factor is the instrument voltage limiter than supplys their power. Good luck

What does the instrument voltage limiter look like and is it easier to pull the whole gauge cluster or do the contortionist act under the dash? My temp and fuel gauges just quit.

Thanks

 

[a68postcar]

it almost looks like a self resetting circuit breaker. it is the only metal box on the back of the insturment cluster. about 1/2" wide by 1 1/2" long. and sticks out about 3/4". it has 2 stabs that plug into the back of the cluster. you cant miss it.

 

[RedFish]

It has 3 heaby gauge spade connecters that go into slts in the back of the panel . There is another small wire in one of the slots also. There are pictures on my website. You might reach up in there and pull the existing one out
but installing the new one aint so easy. Good luck

 

[1969GTS]

Found it. Looks like one of the circuits on my board is fried as well. I'm going to pick up a new one tomorrow and I may as well bypass the amp gauge while I have half the dash apart.

Thanks all

 

[17remfan]

Got my car back today and fuel gauge now works. It needed a new voltage reducer. The temp gauge seems to be still reading low.Ill check the nuts to make sure they are secure.Im really glad to have the gas gauge back..

 

[1969GTS]

Thats great. I hope to have it all sorted out this weekend as well. Ironic we both have 69 GTS's and are having the same issue at the same time. There can't be more than 1500 69 GTS's left on the planet ...... what are the odds.

 

[17remfan]

Well,I recieved great help here that pointed me right to the faulty voltage reducer. I never would have know it .Good luck with your gauges.

I do wonder exactly how many 1969 GTS "s are left.I guess the numbers are slowly reducing .They do seem to be pretty durable with some TLC.

 

[wyoduster]

My gas gauge on my rally dash doesn't work either but there is no limiter on the back of mine... There is what looks like a condenser ,is that it.?? How can mine be checked?

 

[1969GTS]

Fixed! It was a faulty voltage reducer, fried circuit on the back of the board and a broken pin on the back. Some solder, a new voltage reducer and I'm off to the races! Well not quite, but I'm closer to getting the safety inspection.

 

[RedFish]

My gas gauge on my rally dash doesn't work either but there is no limiter on the back of mine... There is what looks like a condenser ,is that it.?? How can mine be checked?

The mechanical limiter is inside the fuel gauge on rallye panels.
Look at www.DeMonIVR.com

 

[17remfan]

Looks like the gas gauge stopped working again. Im not happy about it.The temp gauge never did get working. im probably going to try one of these new Demon units. Thanks for posting that RedFish.

 

[jamesdart]

fuel and temp guage are driving me nuts on the duster. intermitent problem. the both zero out out of nowhere. sometimes you tap the cluster and they work but quickley back to zero. they always do it together so i dont think the guages or senders are bad.

 

[mullinax95]

You going to have to get med evil with it... take the sucker out and make wire it up like it is in the car and do some bench testing.

 

[RedFish]

fuel and temp guage are driving me nuts on the duster. intermitent problem. the both zero out out of nowhere. sometimes you tap the cluster and they work but quickley back to zero. they always do it together so i dont think the guages or senders are bad.

If seen a few panels with loose or broken lenses. Think pet shop,
:stop: DO NOT TAP ON GLASS :stop:
Good luck

 

[17remfan]

I have both the stock tempreture and gas gauge working now.Its great to get reading from both . Its one less thing to do now.Next, I ave to get a properly curved and phased distribtor . It should be my last big hurdle if everything works out well..