I have a 66 mustang. Fuel level does not register on the guage. I bought a new guage, still shows the same. I had the sending unit out of the tank and put it in the full position it only would register half a tank. I think it may be a sending unit problem. I have a good electrical reading. Has anyone else had this problem or an idea for a solution? Thanks

 

no input but i have the same problem. sorry but im going to piggy back off you and try what ever it is that fixes yours.

 

Well, since you replaced the gauge the only thing left is the constant voltage regulator, sending unit(rheostat) and the float.

The CVR is a rectangular box on the back of the dash module. Check the CVR with a volt meter. It should read 12 volts on 1 terminal and 5 volts on the other(that goes to the gauges.

Check the sending unit, off the car, by connecting an Ohm meter fron the terminal to the mounting plate. It should read about 25 to 150 Ohms, low to high.

If everything is good and it still doesn't register when fuel in the tank then the float is probably leaking.

 

There is a very easy way to ground the sending unit without removing it from the tank. When you ground it if the gauge jumps to full the sending unit is ok. Now the bad news: You need someone smarter than me to tell you how to ground it. Someone helped me and I can't remember how he did it.

 

Before I went too far, I would clean the terminal VERY good that goes on the stud from the sending unit. Often corrosion acts like a resistor and can give a false reading. Its easy, free and may solve your problem without work and cost.

 

Excellent advice. The sending units are cheap and easy to install in our cars. I think around 20 bux or so.
Dan

 

make sure the wireing that screws into the sending unit is on all the way, it feels really goofy because it feels like the thread keeps going but that could be causing you to get a bad connection.

 

Thanks for all the help. The constant voltage regulator did the job!

Randy

 

In my 68 the fuel float broke twice and i just replaced it and it worked it just not fun draining the tank