Hi there,
Faulty crank sensor and even bad fuel pump relay should not prevent your starter from cranking the engine. Did any of you ever considered faulty ignition key switch contact block in steering column? Posible burned (dirty) contacts in your starter relay?

 

Anybody in this thread find the problem ? Mine is doing the same thing as original poster.

 

Eventually got situation sorted.
The previous owner to me had installed an extra alarm, which was entirely unneccesary.
The alarm caused the control system behind the dash to create some kind of power surge to the starter motor.
Had to get a new starter motor in the end, and control unit. But this may not have been essential if the problem had been identified.

 

I have a 98 SLK that too has starting problems intermittantly. ie key on but will not crank. May run OK for a week or so then nothing. leave ait a day or two & it starts 1st time! Everything has been checked from forum posts, ie battery, starter motor key-batteries, selector inhibitor switch. The auto electricians think its the imobiliser circuit but its got them stumped. I've read all ther posts it seems to be a common fault across all Merc modlels yet no posts on an actual solution . Someone must have fixed theirs out there by now - please help.
PS have resoldered the K40 board went OK for a week thern back t ousual. Been towed a few time now sob

 

starts but cuts off,fuel injectors are working but wont run but about 30 seconds an cuts off

 

88 300 ce having problem keeping it running,stars an runs about 30 seconds an cuts off

 

different problem to this thread - mine will not crank

 

another different problem
Who has solved the problem of not cranking. Lots of poste but appart from the chap with the aftermatrket alarm fitted no-one has come back to help us out
The fault codes are all communication errors must be the imobiliser but how to fix? Comon Merc owners help me out
MBenz80 had 2 good theories anyone find this the real problem?

 

It's likely that there is more than one problem.
You can verify immobiliser situation with an amp meter by checking that the correct power is being delivered to the starter motor when you turn the key.
I bet it is.. I think it's the starter motor. I think something has caused surges to it, and wrecked it..
Sean

 

thanks Sean - My auto electrician ran a wire to the starter motor from the battery. With the key on it cranks over fine but will not fire
It must be something to do with an imobiliser circuit. Any one know how to isolate & repair it?