C220 Intermittent starting problems - No codes showing.

[Alex Crow]

Could well be an ECU fault - when the fault is present, if you leave the ignition on does the cooling fan run fast?

 

[Johng8seq]

Won't start when hot.

I've been having similar problems with my C220 for some time. Car wouldn't start when hot. Then wouldn't start at all unless I used "Easy -start" - then it would run all day if I let it. Changed the high pressure pump. Car would start when cold but not when hot. Changed the pressure regulator valve O-rings - still no better. Changed the CPS Bingo! It all worked for a week & then refused to start when hot. Today I tightened the clamp bolt on the CPS - now it is working again. I read somewhere that this bolt needs only to be finger tight - not true! The bolt needs to be tight so that the sensor is earthed to the engine - it has a brass insert in its plastic housing which needs to make contact witht he engine. Also I found a much easier way of accessing the CPS than any other description I found on the net. Mine is a 1999 model. I disconnected the water hose from the back of the inlet manifold. This allows you to get your hand onto the sensor to remove the co-axial plug, which then allows you to access the torq bolt with a socket +extension bar. OK so you lose a litre or so of coolant, but it's mostly water anyway! de John G8SEQ

 

[television]

So it was the CPS in your case.

 

[Alex Crow]

...I read somewhere that this bolt needs only to be finger tight - not true! The bolt needs to be tight so that the sensor is earthed to the engine - it has a brass insert in its plastic housing which needs to make contact witht he engine...

I wonder where you read that?
A new one on me!

If you find faults still present, check injector leak off at hot start next.