Crap! Gas gauge acting funny again.

[john berry]

Well, after replacing the float sending unit in the tank of my '88 300CE it's acting funny again. I thoug it was fixed. When I'm getting low on gas, below a quarter tank it jumps back up to about a third of a tank. It seems to jump around between the acurate level and about a third of a tank. I thought I had the thing fixed. What could possibly be wrong? On advise from the MB dealer, I banged the dash a few times with my fist and the needle in the guage didn't budge. So he said it has to be the sending unit. Any advise?

Also, the low fuel light comes on when a quarter tank is remaining. Is this correct. It seems early.

Thanks for you help.