Troubleshooting fuel gauge failures

[JosephGiannini]

With b bodies becoming more and more prized vehicles.
The parts are accelerating through the roof.
And no one knows how to repair the gauges.
Here is a quick and dirty guide to diagnosing your 170 dollar fuel gauge and 70-130 dollar
gauge voltage limiter.

TROUBLESHOOTING PROBLEMS NOT RELATED TO YOUR SENDING UNIT:

THERE ARE SEVERAL ELECTRICAL RELATED PROBLEMS THAT COULD CAUSE A FUEL GAUGE NOT TO WORK.
I WOULD LIKE TO OFFER THE FOLLOWING AS SUGGESTIONS TO ASSIST YOU. FACTORY GAUGES WORK OFF
OF 5 VOLTS WHICH IS SUPPLIED BY THE VOLTAGE REGULATOR MOUNTED ON THE REAR OF THE INSTRUMENT CLUSTER. IF ALL OFYOUR GUAGES DO NOT WORK THIS IS THE LIKELY CULPRIT.. IF ALL
BUT YOUR FUEL GAUGE WORK. TRY THE FOLLOWING:

1. THE BLUE WIRE AT THE SENDING UNIT PROVIDES THE GROUNDING SIDE OF THE FUEL GAUGE.
TAKE THIS WIRE AND PUT IT TO DIRECT GROUND WHILE TURNING THE IGNITION SWITCH TO ACC POSITION.
THE GAUGE SHOULD READ FULL. IF IT DOES, MAKE SURE THE SENDER IS FULLY GROUNDED AND THERE IS FUEL IN THE TANK, BECASUE THIS IS THE PROBLEM IF IT DOESNT READ FULL. GO TO STEP 2

2.THE BLUE SENDING WIRE CONNECTS TO THE INSTRUMENT CLUSTER BEHIND THE DRIVERS SIDE KICK PANEL AND THEN TO A PLUG THAT CONNECTS TO THE BACK SIDE OF THE INSTRUMENT CLUSTER. MAKE SURE THIS WIRE IS NOT CUT ANYWHERE BY RUNNING A CONTINUITY TEST THROUGH ITS WHOLE LENGTH.
IF IT IS O.K. GO TO STEP 3.

3. ON THE REAR OF THE INSTRUMENT CLUSTER CHECK THE CIRCUIT BOARD( A & B BODIES ONLY) LEADING TO THE GROUND IT TO THE BODY. TURN THE KEY TO ACC AND THE GAUGE SHOULD GO TO FULL IF IT DOESNT GO TO STEP 4.

4. CHECK THE GAUGE WITH A OHM METER FOR 12 OHMS RESISTANCE.

NOTE:

VEHICLE POWER CAN BE SUBSTITUTED WITH BENCH POWER OF 12VDC.

MAKES SURE YOU OBSERVE GND TO BE CONSTANT AND SHARED THROUGHOUT THE CIRCUIT.

YOU CAN BENCH TEST THE ENTIRE SYSTEM BY REMOVAL. AND CONNECTING THE CIRCUIT ON A BENCH AS WELL.
OR YOU CAN USE PLUG IN WALL POWER TO TEST THE GAUGE IN A REMOTE SECTION OF THE VEHICLE SUCH AS THE TRUNK OR CLOSER TO
THE VEHICULAR MOUNTED SENDING UNIT.

MOST THE FAILURES OF THIS TYPE ARE GND FAILURES.

[rr6pak]

Thanks for the info JG!

[74roadrunner440]

does this trouble shooting work on 74 roadrunners too

[JosephGiannini]

thsi troubleshooting actually works on most mopars and fords too believe it or not ford uses the same cluster regulator as mopar since dodge was part of ford

[scotts74birds]

Found this also.http://www.moparfins.com/Repairs/Fuel_G ... Repair.htm