I'm having a hard time starting the ML430. When the engine is cold, the first attempt results in the engine cranking over but not starting. Then immediately afterwards, the second attempt is always successful. What could be causing this? I have 53k miles on the vehicle; and just replaced the spark plugs/airfilter and that didn't solve the problem. I'm thinking that it could be one of the sensors...but I'm not sure how to test those???

Several possibilities including a "bad" flywheel sensor, ignition switch, or fuel pressure bleed-off.

IF you depress the gas pedal is there any difference?

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MERCEDES Benz Master Guild Technician (6 TIMES)
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Mercedes Benz Star Technician (2 times)
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27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Yes I've tried depressing the gas pedal while trying to crank it over, that didn't seem to do anything. Is there an easy way to test the sensors that you speak of?

Try using the other key. Someone has suggested that this might have been a problem for us once before. The keys transmit a signal that tells the car's computer it's ok to run.

I've tried using the original key that came with the car, and also the brand new key I got for it a couple of weeks ago. The results are the same...always takes two times to get the engine to start??

I would want to see if the fuel pressure drops after shutting of the engine first! You would need to connect gauge to the fuel rail.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

I guess I'm not sure what you mean by checking if the fuel pressure drops after shutting off the engine first?? Either way I don't have a pressure gauge to connect to the fuel rail. Could a bad input sensor (O2, MAS, etc) cause the engine to crank over on the first try, and then finally start the engine the second try?? Sort of like if the sensor needed some time to warm up...

The usual or more common symptom to a problematic flywheel sensor is the engine will be at operating temperature and it exihibits stalling or difficulty when restarting.

When the engine does start is it smooth as silk or does it cough and sputter a tad?

When the engine does start, it is smooth as silk. And runs like a champ. I mentioned my concerns to the local MB dealer and he thinks that it is probably a bad crank shaft sensor. What do you guys think of his assessment? He also says that for $103 he can conduct a full diagnosis which will pin point the problem for sure. Should I have the car diagnosed? What harm can come from a bad crank shaft sensor, other than it taking two times to start the car??

Not a bad investment for a known problem.

It was the fuel pump/filter and line assembly. Parts/installation for $527 out the door. Thanks for all of your help!

My 2000 ML430 start ok and shut off after a while. And it takes 15 - 20 minutes or longer to start again. When start runs fine is suddenly the engine shutt off again. Please help......

Help anyone! My ML has the exact same problem as dipinj. I changed the fuel filter/regulator and the three attached lines myself and the problem remains. Did you have the fuel pump changed also? $527 is around the price quote that I got for the work I performed, the pump would have raised this significantly. Also Magic, have your Crankshaft Position Sensor checked. I had the same problems in July of '06, cost was $454.56.

Yes the pump was replaced. It is the most crucial part of this replacement. I found a local shop (specializing in MB) which gave me that deal. The dealership was asking around $1200.