I recently bought a 1989 300SE that had been sitting for long enough that the fuel tank was all gunked up. I removed the tank, washed it out with some impressive solvent, then paid someone a few bucks to pressure-wash it inside. Back into the car it went, and it’s now living happily there, and the car starts and runs.

However, in the process of taking the tank out and putting it in, I damaged the fuel level sending unit at the top of the tank.  It’s still out of the car. Today, I know exactly how much fuel is in the tank because I personally poured in a couple of gallons, but once I start driving the car, it’d be nice to be able to rely on the fuel gauge.  Besides, a big, gaping hole atop the fuel tank probably will make anything in the trunk (and maybe the cabin too) smell like fuel.

Now that the car starts, I’m focusing on the sending unit. I spent some time on a donor car today, trying to get a sending unit removed. I failed as to the sending unit itself, because I needed to rotate the entire unit, and for that I needed either an adjustable wrench or a massive socket (more than 40mm, I’m guessing) or a huge wrench — none of which I’d brought along.

However, I learned a lot, and I did get the wiring, which is part of the problem; I’d crushed the black plug at the top.

I’d feared that I’d have to remove the entire fuel tank to work on the sending unit, but, today I learned that I don’t have to do so. After I remove the rear seat back, I can see a shallow, black, plastic plug, and when that’s been pried up and removed, the top of the sending unit is easily accessible.

I love how logically these cars are designed!