If the engine cranks, then the first check is the fuse on the OVPR located next to the battery under the rain drip tray...it hase a 10 amp fuse located under it's clear plastic flip top. Check the fuse and check the manufacures date on the relay. If more than 5 years old, renew the relay... Mercedes updates these nearly every year. About $89.00.
Coils fail too, check for a spark whilst cranking by holding the coil wire 1/4 inch from a good ground.....CAUTION : Ignition is capable of 60,000 volts....do not test this way if you are not sure of what you are doing.
Additionally, you can use a test light on the terminals at the fuel pump with the ignition in the on position. if you do not have current, the fuel pump relay may be the problem. the relay is located in behind the battery behind the black cover. The fuel pump (2 fuel pumps on some models) is/are located under the floor panel close to the rear axle on the drivers side.
If you are sure you do not have spark then your problem could be the crankshaft position sensor... it is a magnetic device that sits in the bell housing at the back of the engine and feeds directly to the ignition control module located on the inside of the engine compartment on the driver side... remove the wire from the module and measure for a resistance of around 900ohms... if it is far below that... then that is the problem... if not that it could be the module itself... This problem plagued me for over a month and many replacement parts later.... from a wrecker yard luckily... it funally solved the problem... Good luck...
start by disconneting the fuel filter on the engine side then turn the key if there is no fuel getting through then it is a clogged filter. if tht is not the problem then your screwed. start by disconneting the fuel filter on the engine side then turn the key if there is no fuel getting through then it is a clogged filter. if tht is not the problem then your screwed.
They are both very important. But a clogged fuel filter will stop the engine from even running. A clogged air filter will hurt performance and mileage but will not stop the engine from running unless it is totally clogged. Replace the air filter every 30,000 miles and the fuel filter every 50,000 miles.