C240 Engine dying!

merc240wales

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have a '99 C class C240 estate (W202). Everything great until 2 days ago!

Engine would not start, turns over ok but would not run. 10 minutes later tried again and started ok. Next day arranged to have it checked by local indy and no fault codes logged. After leaving garage engine died while sat in traffic. Took 1 hour before it would start again.

Spoke to MB dealer and they suggested fuel pump relay so got one in case problem happened again. I did over 40 miles no problem and then died after 3 miles when engine was cold. waited 30 minutes and engine started. But cut out within 2 minutes. can only start after about 30-60 mins.

Any ideas on fix?

:confused:
 

television

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Change the crank shaft sensor and your troubles will go away,

£47 from Bosch service center or £90 from MB
 
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merc240wales

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thanks - any idea why you don't get a fault code in the system? Also is it easy to do on the V6 engine?
 

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merc240wales

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i fitted changed pump relay yesterday, but not sure if it is right one. I fitted relay in relay box under bonnet as shown by MB dealer. Is this teh right relay or is it in the back by the fuse?

Ian
 
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merc240wales

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Fitted new CPS and problem still exists. Good news is that it is happening when parked on driveway. Sometimes it starts and sometimes not! I can here fule pump running each if it starts or not.

Will get computer on it next week to see what is happening unless there is anything else i can try!
 

television

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Sorry about that. is there a spark all of the time when it is not starting
 
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merc240wales

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if i wait about 10 seconds after switching on before turning key to starting position it will start.

I did fill up with a full tank on Wednesday evening just before this problem started. Wondering if fuel was bad.

Ian
 

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I wish we could be of more help but some things are very hard over the net:-(
 

television

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Good point, easy to check with a volt meter on the engine ECU
 

turbopete

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it could be worth checking the fuel pressure regulator too. if it starts after ignition has been on a few seconds, but not if you attempt to start it straight away it could be faulty and taking a few secondsto allow correct fuel pressure. that said, it could be a partly blocked fuel filter so the fuel is slow at getting through to the engine? i was always told to start with the simple, cheap things first!
 
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merc240wales

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Thanks all for suggestions. Car would not start at all this morning despite managing to drive around for about 30 miles yesterday.

Thought EIS may be problem and went to get new one but MB sevice advised that they normally fail and not turn. As my still turned ok they suggested checking other things first. Also replacement cost is about £700!

Mechanic arrived at lunch time and checked for fault codes again - nothing at all. Suspected fuel pump as it appeared not to work sometimes so provided supply direct from battery - worked ok. Suggesting that ECU was not always starting pump! Come to conclusion it would have to go to MB to have ECU checked!

As battery voltage was getting low - below 12V with all the starting. I put it on charge and have since been able to start engine but not every time. Battery appears to be MB original. Anyone come across a battery problem/low voltage causing the problems i have?

Ian
 

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replace your battery with a new one and see do all your problems disappear

cheers
anyweb
 
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merc240wales

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Problem solved

had to take to MB dealer car would not start - they replaced CPS i fitted 2 days earlier and car runs fine!

Thanks for all the help.

Ian
 

television

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Pleased it was that, and all done.:D:D


For anyone reading this the CPS when good measures 1k ohm

when bad open circuit or up to 100k ohm.
 


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