1971 camaro fuel guage inaccurate

[Tom Cuschieri]

So I replaced my gauge cluster from lights to real gauges. I thought I did everything correctly. I went from the large fuel gauge to the smaller original one and now my gauge seems inaccurate. Filled my tank and it reads past full. Not sure where the problem may be. Thanks for any info!

 

[Chuck71RS]

First, welcome to the best place for 2nd gen Camaro.

Before the change, did your fuel gauge needle correctly show the amount of gas in the tank?

Is the smaller original gauge installed where one of the lights use to be?

If so, did you change the printed circuit on the back of the instrument cluster and re-wire the 12 position plug that goes into the instrument cluster? This is also needed.

In my 71, I too removed the fuel gauge and installed a 2inch aftermarket fuel gauge but not in the instrument cluster

 

[Tom Cuschieri]

Chuck,
Thanks for trying to help me out.
Yes, before the switch my large gauge read accurate.
Yes, it is where one of the light was and I did change out the printed circuit board and installed new OEM wiring. I'm wondering if the cluster may not be grounded that well?
Any thoughts?
Thanks, Tom

 

[Chuck71RS]

Tom

1. Are all other gauge needles registering correctly?
   
2. Do the backlights work?
3. Did you install a tach in place of the fuel gauge? Which is what I did. The tac and large fuel gauge go into the printed circuit on the same 12 plug contact
4. The new OEM wiring, does it include the 12 position plug harness that goes into the instrument cluster?

If the answer to all is yes, I would suspect the gauge. Something internally or maybe the connections on the back of the gauge. My aftermarket fuel gauge is not connected to the printed circuit. Is the gauge GM and what year? Ohm range should be 0 to 90-95, which is about what the sending unit operates on. Fuel sending unit should be ok since the old gauge was registering correctly. If you decide to have the gauge tested, contact Daniel at Gaugemarks. Contact info (telephone is best) on the forum in the Sponsor section. He rebuilt my tac and speedo

 

[Tom Cuschieri]

Tom

1. Are all other gauge needles registering correctly?
   
2. Do the backlights work?
3. Did you install a tach in place of the fuel gauge? Which is what I did. The tac and large fuel gauge go into the printed circuit on the same 12 plug contact
4. The new OEM wiring, does it include the 12 position plug harness that goes into the instrument cluster?

If the answer to all is yes, I would suspect the gauge. Something internally or maybe the connections on the back of the gauge. My aftermarket fuel gauge is not connected to the printed circuit. Is the gauge GM and what year? Ohm range should be 0 to 90-95, which is about what the sending unit operates on. Fuel sending unit should be ok since the old gauge was registering correctly. If you decide to have the gauge tested, contact Daniel at Gaugemarks. Contact info (telephone is best) on the forum in the Sponsor section. He rebuilt my tac and speedo

Chuck,
Besides the fuel gauge verything else is working except the tach. All gauges were bought new from classic industries. Lights, temp gauge, volt meter are all working. Yes the new wiring has the correct 12 pin plug.

 

[berg2695]

Is the wire-wound resistor card installed across two of the teminal posts on the back of the gauge? The resistor would have a matching ceramic lnsulator plate between it and the gauge back. This is between the two side terminals (3 and 9 o'clock). Its just a thought. Gotta cover all the bases.

 

[Chuck71RS]

Tom:

Berg2695 might be on to something with the insulator plate. I did not know this

I would also multimeter the tac and fuel sending wires going to the 12 position plug that the tac wire is connected to #1 and fuel gauge to #4. The warning light system that you and I had, fuel gauge is connected to #1.

 

[Kent LaBerge]

Regarding your tach, I had the same issue with my '70 and found the tach gauge has a separate small terminal that is marked as "G" but is hidden behind the printed circuit and does not connect to the printed circuit. There is a small hole in the printed circuit - you have to run a separate ground wire and then your tach should work.