M119 4.2 starting issue (140 CL)

[mercboiuk]

Good evening everyone.

I'm hopeful you knowledgable guys and girls will be able to point me in the direction of what could be going wrong here.

I have been driving my mother's CL420 for the past few days and have discovered a starting problem under very unique parking conditions.
The engine takes much longer and fair a bit of turning over to ignite when parked on a hill.
On a flat surface, it's fine and starts immediately and once started & moving, operation is completely normal.

Going on my very limited technical knowledge, I doubt it's anything electrical and my diagnosis is possible starvation of fuel somewhere. I expect to be told I know nothing of what I am talking about and I'm way off the mark, hence this thread. So my fellow MBClub Members, any ideas?

Many thanks in advance,
Darren

 

[Dieselman]

I suspect the car is parked front upwards when this happens, if so it does sound like fuel is draining back to the tank either as a result of a hose leaking air in or a one way valve leaking.

 

[mercboiuk]

Oops! I forget to mention that it's happened when the car is parked front downward facing.

I haven't tried it with the front up yet. (Although I am concerned it won't start if I park on a hill again )

Darren

 

[diggerfil]

MMMmm...!! Odd situation with it struggling to fire up 'Only' when parked on a hill....

...if it happened all the time I would say it is the fuel pressure regulator on the rail (which would hold pressure of 45-60PSi for an hour or so) or possibly the fuel pump (which should hold enough residual fuel pressure to enable the car to fire up straight away!)

Not sure how or why the position of the fuel tank (away from horizontal) would cause a starting issue .....Wonder if the fuel filler cap is to blame?...not 100% sure but it needs to vent so as not to cause a vacuum in the fuel tank.

Others with more experience may be along in a bit, Good luck.