Fuel Gauge Only Goes to 7/8-No Gas Tank Pressure

[arnel]

My 99 E430 gas gauge is only reading 7/8 full after I fill up the tank. It's been doing this for the last few fill ups. I'm not sure if it's related, but I also notice I don't get that suction sound when I remove the gas cap. I recall always getting a de-pressurized sound when I used to remove the gas cap.

I've seen posts on trying fuel injection cleaner or cleaning or replacing the fuel sending unit. Anybody think that's my problem? I'm not comfortable removing and cleaning the fuel sending unit myself, but I wanted to get some feedback on what it might be before I bring it to the dealer and they charge me an arm and a leg replacing parts that aren't broken.