E320 Engine stalls while driving and or will not always start

[Grumpy]

Howdy folks, I am looking to the brains trust here. My wifes E320 has decided that it does't want to start when warm. When it does start, it then runs for about 10klm's and refuses to start until it cools a bit. Or at least, that's what it appears to do. I initially diagnosed it as a fuel pump relay. I replaced it with immediate good results, however 30klm's later, it wouldn't restart for ages. What I do know is, the fuel pump relay is new and good. The fuel pump appears to be good, although I haven't done a pressure test. Filter good as well as coolant temperature sensor is good. I guess the crank sensor or cam sensor could be dodgy, however in my experience they don't appear to be consistent with the issue. So I am hoping someone has some good advice for me. It's a real good car, so it would be a pity if I decided to park it in one of my paddocks.

Kel

[CraigB]

I don't know your model but on a W126 a bad fuel accumulator can make warm starts difficult. Although once running its not normally a problem. Also on a W126 if I was suspicious that the new fuel pump relay could have an intermittent fault, you can bridge two of the pins so it runs constantly and that would just tip you off short term if it changed the behaviour. Just thought i would share that but hopefully and expert will soon follow with info.

[Grumpy]

Thanks Craig, yes, done the jumper wire trick. Doesn't help it start when it stops.

Kel

[Ivanerrol]

Are we a M104 or M112?

M104 temperature sensor can be suspect

[Grumpy]

( Ivan) It's a w210 E320 2000 I isolated the coolant temp sensor and thought it fixed it. However it happened again. ie. did about 15k and it stopped and wouldn't start until it cooled down. Fuel pump made its usual sound when not starting.

Kel

[Ivanerrol]

Any fuel smells around the fuel pump?
2000 era we are in the era of computerization.
Also. 2000 - update or older model? Update has some more OBD built in.

[Ivanerrol]

I had a CPS fail on my W204.
Initially warm start failure. Cheap to buy the part but a bollocks to change over. - Didn't cause engine failure while in operation though.
Buy some MAF cleaner. Try that. MAF's are $$$$

[Grumpy]

Any fuel smells around the fuel pump?
2000 era we are in the era of computerization.
Also. 2000 - update or older model? Update has some more OBD built in.

No smells, it's a good clean car, never had any problems. Yes it's an update model. I will try an crankshaft position sensor and see how I go :)

Kel

[John Green]

My money would be on the crank angle sensor. Get a loom set up so that you can plug onto it when it wont start and see if it is open circuit. This is a typical failure, when it get hot it expands and goes open circuit, the engine control module doesn't know what the crank is doing, so it shuts down. Then the sensor cools and contracts once again making contact and away you go until it heats up again.

[Grumpy]

All fixed and running like a dream again. Thanks for advice from others. It was the crank angle sensor. I managed to pick up one just around the corner from from a mate. Cheap easy fix, it took me about 20 minutes all up. Fortunately I had the correct tools for the job and many years of work experience :dance: .

Kel