How do I replace a fuel tank sending unit?
 

in a 1991 560SEL?

My gas gauge is flakey! Is it necessary to drop the tank?

On my '85 W126, I removed the rear seat back. The sender is on the driver's side on top of the tank.

If you have the power rear seat, all that has to come out, its under the lf rear seat back just below the shelf ledge, 46mm socket.

I've had success taking the units apart and cleaning them out in the past.

Don't be too disappointed if you still have a flakey gauge after replacing the sending unit.

Whwn I bought my 85 380SE the gauge would jump all over the place especially when nearing 1/4 to R level. Two treatments of Chevron Techron solved the problem. Gauge works perfectly.

You are lucky. One of my 124s has that problem, one doesn't. I swapped the sending units. It made no difference at all to either car.

Breeze of a repair
 

I think I posted something on the DIY forum. For my 1991 300d, it was a breeze to repair. The problem was that rust gets on the shaft from the former owners never filling it up all the way, or in my case, the car sat for months on end without much fuel in it, and so it rusted.

Take it out, hit it with a dremel or Rotozip, with a round sanding bit, to sand it down where needed, put it back. Read on how to do it first, if you don't see anything, e-mail me directly and I'll send info.

jeff
1991 300d, 99k