Thoughts on gas gauge fix

73' mach 1 · Dec 24, 2015

Sorry if this has already been tackled but I'm trying to fix my tach and speedo and was reading thru past posts. It seems a lot of people replace the flex circuit board and CVR. It also seems that after replacing the CVR the gas gauge is a little inaccurate correct?!? I'm not sure if it could apply here too but when I was doing my caprice up I installed a Z28 dash cluster which did the same thing to my gas gauge. All we had to do was essentially take a 10K potentiometer inline with the line to the gauge. This way you could just dial the needle right to the full line rather than the 5 gallons or so you burn before it even touches the line. Thoughts? Again...sorry if its already been done.

Jeff73Mach1 · Dec 24, 2015

Electronics are out of my comfort zone-but I will note that the original CVR's had a small screw and could be adjusted, just as you are proposing.

Don C · Dec 24, 2015

Yes, you can do that. To eliminate a potential failure point you can replace the potentiometer with a resistor of the value the potentiometer is adjusted to. Potentiometers tend to corrode when not moved occasionally. You have to be careful when doing this, though, getting it to read full may make it read 1/4 or 1/2 full when it's empty.

jbojo · Dec 24, 2015

My gas gauge is reading low so I have been playing with the idea of putting a resistor in parallel to the float mechanism to make the correction.

EDIT: Got to think about this a little more. The sender should read 10 ohms when full and 73 ohms when empty. Going to try to run a few numbers through the parallel resistance formula to see if this will work.

Edit 2: Looks like the only way to correct this problem is to bend the float rod or adjusting the CVR if possible if it is not putting out the full 5 volts.