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Q: my engine cranks but does not start

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hi. ive got a mercedes E300 TD from 1999 and the issue is that the engine just turns and turns but does not start, i think it might be the fuel pump but im not sure, its been two months since the car drove last time.

My car has 343750 miles.
My car has an automatic transmission.

A: While it is natural to suspect a fuel pump ...

While it is natural to suspect a fuel pump right away when a car does not start, there is a good chance other issues could also be going on here. Diesel engines, like the one in your Mercedes, need two things to start up. The first is proper compression, the second is the correct amount of fuel being injected into the combustion chamber at the right time. If your engine has good compression, (meaning the vehicle is not losing compression in the cylinder head due to bad piston rings, bent valves, or a blown head gasket), then we can begin to suspect that a lack of fuel, a weak battery, or failing glow plugs are behind why your Mercedes Diesel engine is not starting.

However, to really know if your vehicle has good compression, it is highly recommend to enlist the assistance of a certified technician to stop by and go over your Mercedes with you in person. They will have the experience and tools needed to accurately check both the charging system and the fuel pressure and determine why your Mercedes is not starting. From there, they can let you know exactly what repairs are needed.

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