hi guys, my 2000 ML 320 dies every now and again and will not start up again, It cranks hard and strong, seems to be dry cranking so I checked for fuel pressure on the fuel rail and it's not building fuel pressure.

I changed the fuel pump and filter to the upgraded filter and lines and thought it was all good, but it just did it again!! Died in traffic, and will not build fuel pressure. I swapped the horn relay with the fuel pump relay and after a few tries it started again, but i'm not convinced it's a relay problem...

What else could it be?? is there a sensor or something that will shut off fuel supply or something if it's going bad? (will a bad crank position sensor do this)

The problem is intermittent however seems to be getting more and more frequent.

Any help would be much appreciated, I need a reliable car, I can't afford to have this happen with my baby boy riding along with me.

Thanks
Shalil



additional info:

It's got 110K miles on it and I just recently did the 100K service on it where I replaced:
Fluids: Engine, Transmission, transfer case, fornt and read diffs
Filters: Engine and Transmission
Spark plugs (irridium)
O2 sensors

more recently:
Fuel pump(BOSH) and filter

Current problem is not resulting in any codes either...

The culprit CPS - crank position sensor. there`s a lot of DIY/info in regards to this.

yep. Had this happen on my car last year.

Have you checked you fuse box fan to see if it is working? I have had simular problems. I removed the fan while looking for a replacment that doesn't cost over $200 and so far the problem hasnt returned. I will need ot get the new fan in before the weather heats up or im sure ill have problems again.

Changed the CPS and all is good, I have an extra crank position sensor : Bosch 0261210141 Engine Crankshaft Position Sensor for sale if anyone needs it, I ordered it only to find it's not the correct one for my ML...
$35 plus shipping takes it!

Thanks for the help guys

I`m happy for you,man.

Thanks bud, just wish I hadn't spent $400 on the pump filter and fuel lines tho....But I guess she's good for a long time now...

Unknown to many mechanics the problem can be solved by replacing the faulty ECM. I spend thousand of $ to find out that it was either the airflow sensor, nor the radiator coolant sensor or the spark plugs etc. Mercedes was apparently aware of that deficiency but kept the mechanics in the dark. However, in the US after aprox. 150 complains the ECM's were replace at Mercedes costs now matter how old the SUV was; unfortunatelly in Canada they refuse to honour to replace at their expense that faulty computer.

Wow, I sure am grateful thats not the issue with mine, the total bill for me came to $535, including the fuel pump, upgraded lines and filter, the CPS sensor(got 2 of them, the first one landed up being the wrong part, got it for sale incase anyone wants it, $35 takes it: part # Bosch 0261210141 Engine Crankshaft Position Sensor) and $60 for the MB tech to diagnose it for me, I did all the work myself, hence the savings...

But I was getting worried that it could be the ECM....don't even want to know what that would cost to replace...

So if a faulty CPS causes the fuel pump to not operate, how do you ever know if your no-start is due to a dead fuel pump or a faulty CPS?

well seems like the diagnosis can be made with a code reader, I have a good one and was not able to dig up the code(may be user error), the MB tech that helped me diagnose it used his fancy Snapon blue point reader to find the code that showed it was the CPS, however, it would be much cheaper to start with the CPS, Unlike me you would save $400...