I am having an issue with the fuel gauge on my '71 Comet. It started reading much lower that the amount of fuel I had in the tank. It would then work right for a day or so than go back to reading wrong. I did wiring check by reversing the wring connection at the sending unit and jumping the wires together. I expected to see the fuel gauge read over full but it didn't move. That kind of tells me the it's not the sending unit. I wanted to hook up a temp gauge but read you cannot do a direct powered wire to the sending unit without a regulators because it will fry the sending unit. That made me think is their some kind of solenoid or regulator on the dash gauge panel that controls the power level to the fuel gauge? That could be my issue. Any other suggestions would be appreciated.
Do you know what the part# is and where I could get a replacement. Would you happen to have a diagram of where it would be on the back of the panel.
As noted previously, the constant voltage regulator is located on the back of the instrument panel. You'll have to remove it. The connector looks like 9V battery connector. Be very careful in removing the connector from the regulator - our Mavericks are old, and plastics (including the printed circuit board) are brittle. Also, if you've never removed your instrument panel before; you have to disconnect the speedometer cable (clip). Perhaps some other members recall where the links are in technical...? I've attached a wiring diagram, two listings: Autokrafters & Melvins, picture of the regulator, and a view of the printed circuit board. I bought mine on e-bay.
im aving the same trouble except mine does the opposite. i bypassed the old regulator when i redone my gauges. it worked fine for a year and now half tank equals empty. i pulled the wire to the fuel tank and cleaned the connector and it worked fine for a week. now its wrong again. i think mine is the connector.
OK. So I pulled the gauge cluster out and replaced the voltage regulator. Now when I attach the wires back to the sending unit the fuel gauge is buried past full to the p0int you can not see the red needle. I have a 2 prong sending unit and either way I put the wires on it I get the same fuel gauge reading. What is this now telling me? On anther note the harness that clips into the gauge cluster is missing one of the clips. It was taped in with electrical tape. Can we still get the harness attachment and replace the wires from one to the other? Thanks!
Make sure the "body" of the regulator is screwed in, and making a good ground connection!!! If you're handy at soldering...take apart an old 9V battery - the connectors can be used as replacements.
The regulator is screwed on tight and the connections are tight as well. The wire conductor film was not in the best of shape but did not look damaged.
If you have a volt meter, measure the voltage between chassis ground, and (one at a time) the two contacts on the voltage regulator. The input side should read 12V, and the output side should read 5V.
Satchelmcqueen: What do you mean that you "by-passed" the regulator? Put a jumper wire across the regulator?
Well I don't have a voltmeter nor would I know how to do that. I am horrible at electrical. Could this be the sending unit?
I'm having a similar issue and I'm glad I'm not alone. I had to replace the sending unit in my 76 Comet cause the original was toast and always read empty. Replaced the unit, added 5 gallons of gas and the gauge still reads empty. Is the voltage regulator behind the cluster panel a common issue that causes this?
Common cause - Yes, but could also be a wire, connector or grounding problem. Yes, the regulator is on the back-side of the instrument cluster. Regarding a voltmeter: Easy to use. If you have a Harbor Freight near you, they are cheap. (See attached photo) In fact, sometimes you can get one for free with their coupons. Just follow the directions for measuring DC voltage. Set the dial to the appropriate volts/measurement. Attach the black lead to ground (metal surface on the car), and touch the red lead to one side of the regulator, read the meter value. And then, touch the other side of the regulator. read the meter. If you can chase down a water break, leak, or plug in a pipe; use the same skills to chase down an open in a wire.
