- This topic has 6 replies, 2 voices, and was last updated July 26, 2005 at 7:03 pm by
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My fuel gauge is not registering;stays left I have a replacement for the sending unit but haven’t installed it yet[is it the sending unit or a loose gauge wire;or the instument constant voltage regulator?[other guages including temperature all work].So I’ve been resetting the odometer with each fillup and calculating the miles per gallon at about 13-14.Seems low.The engine is A-1 recently rebuilt;the carburetor is a Holley 600 CFM;car starts easily and runs nicely;I recently replaced the electric fuel pump with a NAPA Carter unit;no leaks visible.Any thoughts?Forgive me if I don’t respond to your replies for a few weeks but I’m off to Ireland tonight and I just had to post this inquiry. I will reply upon my return. I know one fellow in Ireland that has a beautiful Alpine but I’ve seen no other Alpines or a Tiger ❓ on the roads. frank mooney
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Frank,
The temperature gauge and the fuel gauge both get power from the instrument voltage regulator (~10 volts). The circuit goes from the IVR, through the fuel gauge (which is really a current meter) to the fuel gauge sender (which is a variable resistor) and then to ground.
Since your temperature gauge works, the IVR appears to be supplying power (maybe not the right voltage, but at least it is not dead). You can use a voltmeter to see if there is about 10 volts getting to the fuel gauge terminals.
A bad connection anywhere in the circuit will stop the current flow and make the guage stay on empty. The only difference between the fuel gauge and the temp gauge is the markings on the face; you can swap the wires from the fuel gauge and temp gauge to see if the fuel gauge is working. The fuel gauge sender should measure about 33 ohms in the full position and 240 ohms in the empty position.
I would bet that you have a bad connection, a broken wire or a bad ground at the sender.
Have a good trip to Ireland!
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Barry,one further inquiry re your comment that it could be a bad ground at the sender.The sender is on and in the drivers side fuel tank.The sender wire at that juncture appears ok.I’ve cleaned the wire and spade connector at that point.The tank is grounded[so I believe] by its affixing bolts to the chassis.if so how could my ground be bad? frank
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Barry,the gauge is now working.I replaced the sending unit with the spare on hand.I tested the unit first out of the tank by hooking it up to the gauge and grounding it.It worked.I was able to remove the old sending unit with a minimum of effort[a first for me] and install the replacement which worked in the tank.The old sending unit appeared to be fine but something was wrong.I haven’t taken it apart or otherwise tested it.Thanks for the info. It is comforting not to have to see an E all the time.
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Frank,
Sorry, I missed your post on the 13th, but I’m glad to hear that you found the problem.
When you open up the sender unit, you will find that it is very simple; just a wire wound resistor with a contact that is moved by the float arm. After 40 years, some of this stuff just gets tired.
In my opinion (yes, I know), the vast majority of electrical gremlins in Alpines and Tigers are caused by poor grounds. Instead of using ground wires, Rootes mostly depended on the mounting fasteners to provide a ground circuit (or not, as the case may be). Of course, after 40 years, the wiring harness also tends to be a little “crunchy”, but that is another issue.
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