fullt tank reads 2/3 OBC shows range of 359 miles

[cobb535]

I have filled the tank twice now and this time I filled till the filler neck was full. The gague reads 2/3 after totally filling the tank and will go down as I use gas. The OBC range reads 359 miles and goes down as I use gas. The fill up at the gas stationg today took 8.5 gallons from a gague reading of 1/4 tank. I'm thinking fuel gague or instrument cluster since the computer gets the same tank level signal and reads what I think is normal. The car is a 1989 535 that I got recently. This is the first couple of times I have filled the tank.
I tested the sending unit accoeding to bentley. I got 58 ohms on a little over a quatrer of a tank on the gague but not on the pins Bentley told me to check. The car has a build date of 11-88 if this helps. I have another cluster and sending unit in my parts car (build date 8-88) but don't want to do unnecessary work.
Any help would be appreciated.

[Jeff N.]

Not familiar with the Bentley test but from what you describe I'm almost sure it's the sender.

Should be able to get one from a salvage unit. Not a hard swap. You'll want to do it when the fuel level is really low and you'll need 2 fuel line type hose clamps. (The sender and fuel pump are connected and come out as a unit; you'll need to undo the oetiker clamps and replace them with the fuel line clamps).

I had a bad sender and it pretty much worked as what you've described here.

Jeff

[mikell]

Ditto. Had the same deal - after a while, it got real intermittent. Changed out the sender and all went back to normal.

Be sure to run the tank as low as you can before you do the swap - reaching down into a tank full of fuel con't be much fun.