I have to replace the two fuel sending units in my 1999 C280.

Does the gas tank have to be removed to replace them or can they be reached under the back seat?

 

Someone feel free to correct me if I am wrong... I think you have to access that tank (and corresponding sending units) from underneath the vehicle. If I remember correctly, that tank is plastic. Nonetheless, be careful about what you beat around in there, even if the tank is empty you'll have extremely flammable vapors. My C43 has two round access 'ports' - for lack of a better term in the front slope of the tank. They're located at the 45 degree slant of the tank. The whole float assembly is accessed through that port. You have a 280 so I might be wrong, my C43 began its life as a C280, so I'm only guessing it's the same. Removing the rear seat cushion is a snap - you have a toggle at the front of the cushion (one at each side of the cushion). Toggle/push laterally from side to side - I believe towards the the door and push up on the cushion - voila! Once you're there you will be able to tell if you can access your tank. Hope this helps.

I had an intermittent fuel sending unit problem and it went away, for now. Bought all the parts but while it works I'm not undertaking the task (I always back-up the gauge) and it's usually ready for a fill up at around 280-290 miles on the odometer (in-town driving).

I contemplated how to best tackle the problem and my strategy was to get the car down to empty (if the sending unit didn't work again). Jack up the front in order to have the remaining fuel slosh back with gravity. And finally remove those fuel sending unit 'doors' to R&R the fuel float. Those 'doors' look like plastic portholes.

 

The fuel senders (2) have to be accessed from under the vehicle. It really is something best done on a hoist and not on jack stands. One sender is easy but the other can be tricky due to the jet pump hoses in the tank. Tangle these up and you won't get any fuel after 1/2 tank.

 

I agree, I don't have a hoist though. At any rate, it has been a problem with many of the W202's - I only have the problem very rarely and it's when I 'overfill' the tank.

 

Thanks for the help!

I was overfilling the tank which probably hurt the sending unit(s). Now when I fill up, I only round up to the nearest $.25

I ran Chevron Techtron cleaner a few times which seemed to help.

Now when I fill up, the gauge stays on empty for 25 miles, then goes up to full. I can live with this small annoyance if it stays this way.