fuel gauge woes :(

[tkisling]

When I bought my 81 rabbit Diesel the fuel gauge worked fine. It was accurate too. But one day I noticed the needle had been just above 1/2 a tank for a LONG distance. After removing the back seat and accessing the fuel sender so I could solve a different issue inside the tank. I connected the sender to its electrical connector when it was removed and moved the float up and town to see if the gauge responded. It did. I put it back EXACTLY as the Bentley manual had said. The fuel gauge will go to the "full" position when you fill the tank. But it will not go down past "just above 1/2 tank" position. 

Why doesn't the gauge go down?

heres a pic of where the gauge doesn't move below:

http://img822.imageshack.us/img822/1346/img0986y.jpg

[DCC]

This is the classic fuel level sender:


The black thing goes up and down floating on the fuel. I think that maybe it's phisically stuck and won't go past the 1/2 position, or there's a problem where it meets the electronic track. Either way, easy fix. 

[tkisling]

The arm on the sender moved easily and freely when I hooked it up to its electric connector outside the tank. It seemed to work perfectly with the gauge outside the tank.

[DCC]

The arm on the sender moved easily and freely when I hooked it up to its electric connector outside the tank. It seemed to work perfectly with the gauge outside the tank.

Were you able to measure and check resistance (I think it's resistor type) with a multimeter?

[tkisling]

no, but the gauge moved up and down while I moved the sender's float up and down.

[motomike33y]

Did it go all the way from empty to full while outside the tank?  If so, sounds like it may be hanging up or getting caught on something inside the tank.  Have you looked in there with light to make sure nothing extra in the tank?

[tkisling]

Yep, worked fine with it outside the tank. Me and my dad think it must be sticking on something in the tank.

[DCC]

Yep, worked fine with it outside the tank. Me and my dad think it must be sticking on something in the tank.

Hmmm, maybe it's touching something on its way down. Try to rotate a few degress the sender and see if there is any difference.

[Quantum TD]

Check the ground screw.

It's located under the carpet along the front edge of the rear seat. Basically, pull the rear seat, and then peel back the carpet on the passenger side (enjoy the goo!!!).

You'll find the ground screw for the sending unit buried under the mess of goo and nylon hair. Unscrew it (phillips), and install a larger DIAMETER screw. Make sure it's the same length. The larger diameter will freshen up the metal contact and improve the gauge reading.

I've done this several times to old Caddy trucks. It's the only thing that fixes the gauges.

Good luck

[tkisling]

Did your gauges hang somewhere in the middle like mine?

[Rabbit on Roids]

when my gas gauge is about on the empty mark, well into the red, it only takes 7-8 gallons to fill up my rabbit. so it reads way low..

[Baron VonZeppelin]

Tkisling - does your fuel gauge go back to Empty when the car is off ? Or does it still hang midway ?

After doing an oversize ground screw - if no change - the next thing to check would be to siphon or drain most all of the fuel out of tank - and recalibrate position of the sender in the tank until it reads E on the gauge.

[tkisling]

The needle does drop when the key is off.

[Baron VonZeppelin]

Okay, if the ground screw upgrade is no help - then you'll need to do the other thing i listed.

[tkisling]

The gauge magically started working on Sunday until today when it jumped back to above 1/2 a tank again after being below 1/2.