C body fuel gauge

ALLAN · Post by **ALLAN** » Tue Feb 21, 17 5:28 pm

Am I right in guessing that the power for the fuel gauge comes off the dash circuit board/ignition switch through the gauge and is earthed through the sender,which in turn is earthed through the tank.
with ignition on should there be 12v at the sender ?
should there be no resistance between the sender body and tank and tank to chassis.
does the dash voltage regulator affect this
problem I have is a completely dead gauge,needle doesn't move at all when switching ignition on. the car came with a new sender unit but my gut feeling is no power to it,dash off to get to it

Demon James · Post by **Demon James** » Tue Feb 21, 17 5:36 pm

Is there continuity on the wire from the sender to the dash?

Faulty dash voltage regulator is also a common one, should be 5 volts DC.

Another poor connection point is the dreaded bulkhead/firewall connector, definitely worth a check.

Is the sender well earthed/grounded?

Mine was poor cable quality, too much resistance due to age and also a duff 5 Volt dash regulator.

I made an electronic regulator and replaced the wire so it had no joints or connections, just terminated at the multi-point plug on the dash and then at the sender

Sandy · Post by **Sandy** » Tue Feb 21, 17 10:22 pm

I used to know this... sigh.

I am pretty sure it is all tied up with the 5v module.

If you can get the wire off the sender, turn on the ignition and earth the wire to the body shell. The gauge should rise to max. Don't hold it on for long but a helper can tell you if it maxes the gauge, or if you are quick, you can see the needle fall as you run back to the driver's door.

If the needle does move when you do this, the 5v module is okay. If it doesn't, it is either the module, or a wiring fault.

latil · Post by **latil** » Wed Feb 22, 17 8:04 am

Check the earthing strap between tank and fuel line,it bridges the short rubber connecting pipe to earth the tank. Often corroded or even missing.

ALLAN · Post by **ALLAN** » Sun Mar 19, 17 7:50 pm

Well that's that sorted

I think...after draining off enough fuel to top off my daily driver and some left over( nothing like a gob full of unleaded to start the day 😣) a new sender slotted in , a new terminal crimped on,all earth straps cleaned the needle now moves...Woooo.😊 just needs a proper leak check and an open road, oh I did find a lovely drain valve buried under the crud,,and the float was missing from the sender I took out