70 skylark Fuel gauge sending unit

**Buickboy89** · 01-24-2009, 10:33 PM

What do I need to do to change the sending unit in my 70 buick? the gauge is pegged at past full. Thanks guys and btw Im Kevin.

**BigNastyToyota** · 01-25-2009, 05:45 AM

Before you do the replacing the fuel sending unit,I'd make sure the ground is good. In the trunk,there is a square plug that goes to the wire for the sending unit.(runs through a grommet) Take that apart and make sure you have an absolute good ground.Then turn the key on, Ground it and if the gauge moves,Its a ground and not the unit. But,the wire to the top of the tank may also be bad,To get to that,one must lower the tank to access it. It may be smashed next to the tank or could be unplugged.

**Buickboy89** · 01-25-2009, 02:57 PM

I should have noted that when the sending unit did work the gauge would move go back and forth between 1/4 and 1/2 when I would have about 1/2 tank of gas.

**Flynbuick** · 01-25-2009, 03:58 PM

It still could be the ground. A full peg will occcur when the ground wire leg becomes an open circuit.

Otherwise drain the fuel as low as possible, disconnect all electric, fuel and vent lines and hoses. Then you remove the retaining straps while tank is supported by jack with a block of wood on the pad. Lower the tank and tap the retaining ring counter clockwise until it unscrews. Replace the O ring and the unit or send the old one out for a rebuild after performing an ohm meter check on it to see if it is really defective. It is just a variable resistor operated by a float which should not have any fuel in it. Then reverse the process.