Moparts Tech Archive
Fuel gauge - Grounding
What a tease--I looked around the engine compartment the other day and noticed no ground strap from the engine to the firewall...That's been in the back of my mind for a while as a possible reason for my fuel gauge being on the fritz---Yesterday I was at a friends house helping him get his '67 GTO back on the road when I asked him to ground the engine to the firewall for me while I turned the key on. He grounded the bolt on the choke well to one of the bolts on the blower motor on the firewall. I turned the key on, and EUREKA! THE GAUGE MOVED!!!
So I go home, all excited. I make up a nice ground strap, attach it to the same bolt for the blower motor, and attach the other end under the coil mounting bracket. Run back in the car, turn the key----NOTHING!!! What's going on?
BTW, what did the original ground strap look like, and where did it connect?
I'm a man on a mission here.....
Before my instrument panel redo, the thing used to work....sort of..
I replaced a perfectly good sending unit with a Year One repro when I replaced the gas tank a few years ago. Worked good for a while, but then the float sunk. I've got a line on a brass float at a nearby, uh, Ford dealership. (I'm told they're the same size)
I'm gonna drop the tank (again) and replace the float, and then I'm gonna ground every thing to everything else 'TILL THAT MUTHA WORKS!!!
Shouldn't have to drop tank to replace float. Just run real low on gas or siphon, and you should be able to get sending unit out. Just be careful and disconnect battery, and use a brass punch to remove retaining ring if necessary. You really don't want to cause a spark down there now do ya! Good luck!
FYI, the brass float is Ford part # C0-AZ-9202-B
$4.95 at my local Ford Dealership.
1) Engine ground goes from anywhere on the block to the firewall(if you haven't had one before, you might find the motor will run better with it. )
2) check and make sure the ground strap on the sender is WELL attatched. The guage will not work without that ground.
3)Is your temp guage working? If not, it might be the 5 volt reducer in the instrument cluster.(3 pronged rectangular box plugged into the back of the cluster)
4)If all above is in correct working order, crawl under the car and ground out the sender wire on the tank. If its' working, it should show "Full". If not, replace the guage.
5)If you still don't have a working guage, it is either the sending unit in the tank or the float. For floats, I prefer the '80 GM version. They are foam and cannot sink....they will also snap into the float rod of older MOPARS.
6)If that don't work, the only think left is the tank sending unit!
I had a similar problem with my fuel guage and it did end up being the dash voltage limiter on my rallye guage setup. But my other guages running off the limiter were effected also. My limiter was putting out a constant 12 v instead of the fluctuating 12 v to 0 v. I converted to solid state using the directions posted in the tech archives on this website get a contant 5 v and have had no problems since.