Mechanics

THE CAR WILL NOT START. ONLY CRANKS FOR TWO SECONDS

1999 Mercedes Benz SLK230 • 150,000 miles

The engine will not start. Only cranks over for 2 seconds and stops. Have to turn key all the way off and then try again. Engine is getting fuel and fire. It had a very bad fuel leak at one of the injectors which was just repaired
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Rnoel84
September 22, 2011.




There are a few possibilities.
As far as the car not starting. There are a few sensors that are part of the part circuit, but 2 that must be working properly and mounted properly to create spark at the right time. There is a camshaft position sensor that times the number 1 cylinder to be in time with the cam which is in time with distributor, thus creating spark at correct time. The is also a crankshaft position sensor, 2 on the larger motors, that make sure the crank is in time with the cam and is also part of the timing circuit.
One part that creates the start signal as well as the prime signal for the fuel injectors is the electronic Start control Unit. If this is failing, the starter will not turn the motor. It can fail intermittently and could be a possibility.

The leak at the injector is the most disconcerting. Fuel injection pressure is about 55psi at least at the fuel rail and can flood a cylinder quickly. This can cause hydro lock where the cylinder is so flooded with fuel that is locks up and cannot turn.

In any case, there are enough possibilities where you should get an OBD trouble code reader hooked up and get the trouble codes. Any repair shop will have one and can usually tell you what the computer sees as a malfunction. However, some mechanical malfunctions or intermittent failures will not throw a code. But you have a problem that occurs every time you try to start the car.

First, get the trouble codes and I will double check them for you. Second, the likelihood of the injector hydro locking the cylinder is pretty low, however it is something that could damage the motor. It takes a lot of fuel to do this.
Where is the leak coming from?
Was the injector replaced or just the seal?
If an electronic unit like the starter module is failing, it should throw a code.
There are enough possibilities that it will be a process of elimination to track down the problem. However, make sure you adress the above first as it is a good starting point.
I will keep an eye on this post for your reply. Whomever fixed the car might have already run and OBD check and have the trouble codes. So, call first to save a trip.



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