Looking for a crank sensor or fuel pump sensor

And you're looking at these because you've performed a diagnosis to see that something has failed? Then you've tested for power and ground to determine that the sensor(s) are not responsive? Guessing isn't the best choice. First, if you're asking about the crankshaft sensor or fuel pump sensor (if there was one), you don't even know if you're lacking fuel or spark in the first place. A good diagnosis that will end up saving you money in the long run is what you need to have performed. This will determine if you have a fuel delivery or supply issue or a spark / ignition system issue. Once you find out that part of the equation, it can be pin pointed further to find out what the source of failure is. Guesses are just that -- guesses. And you can maybe guess right, but far more often it's throwing money down the drain and even then -- replacing known good Mercedes parts with replacement parts of sometimes inferior quality...that even complicates things more potentially...