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.

[yal]

I thought this usually happens becuase of a bad ground connection in the trunk near the antenna?
Someone please correct me if I'm wrong. Thanks.

[mpolli]

If it was a bad ground then wouldn't it happen at more random times? Not just when it is below 1/4 tank? I am guessing sender, but I don't have knowledge of that specific car. I searched and found a thread "300CE fuel tank problems" but it is a little unclear what it is talking about. Might help you.

Mike

[csnow]

Yeah, I have that too. Replaced the sender to no avail. Gave up.

[raymr]

Ditto. It wags all over the place below 1/2 tank, but the low-fuel light still comes on at the right time. I think it only happens while moving, so it seems it would be related to fuel sloshing around in the tank.

[sstk100]

I have a 1988 260E and the gas gauge works some of the time, then not at all for a while.

Any ideas?

Thanks!

[brewtoo]

Hmmm...lots of us have this bouncing gauge problem but I've never seen a fix posted. Our '91 bounces. Our '90 does not.

I swapped the sending units between the cars and it made no difference. I tightened the big ground on the driver's side of the trans and it helped some, but it's still not right.

[schumi]

I posted a fix that worked for me about 2 posts previously.

Originally Posted by brewtoo

Hmmm...lots of us have this bouncing gauge problem but I've never seen a fix posted. Our '91 bounces. Our '90 does not.

I swapped the sending units between the cars and it made no difference. I tightened the big ground on the driver's side of the trans and it helped some, but it's still not right.

[schumi]

I had a similar problem that resolved after using some redline fuel system cleaner, available at pep boys. since you replaced sending unit, your problem may be elsewhere.