W202 C250 TD How To Bypass Fuel Pre Filter

[Sinc1964]

Hi all,
I have been having the usual W202 problem of difficult starting due to air getting into the fuel lines and allowing the diesel to flow back to the tank overnight.
Usual thing, park it with the nose pointing downhill and it will start fine.
I have replaced all the clear plastic fuel lines with genuine MB parts, fitted new O rings all round, replace the rubber fuel lines with new ones, replaced the steel fuel lines.....still the diesel flows back to the tank overnight. The clear plastic fuel line to the fuel pre filter (near the main fuel filter) is always empty of diesel every morning. I have fitted a fuel primer bulb (as per old school Peugeots) which helps but fed up of having to use this all the time.
Is there any was of by passing the fuel pre- filter ???

 

[carat 3.6]

I'd be willing to bet that you have leaking delivery valve seals, but the only way to bypass the pre filter is with a length of rubber pipe fitted onto the plastic ends of a spare pipe.

 

[a111r]

Is the top of the injector pump wet by the steel lines' unions? DV leak clue, if so.

Did you change the shut of valve O-ring? Another prime contender.

 

[wu56Shoozz]

You can buy a non return valve from Facet and break into the line and install, there are different sizes of fuel line so you would need to measure to fit..

Similar to this:

Fuel Non Return Check Valve One Way Petrol Diesel 8mm New | eBay

 

[Auto-mobile]

Is the top of the injector pump wet by the steel lines' unions? DV leak clue, if so.

Did you change the shut of valve O-ring? Another prime contender.

As above.

 

[Sinc1964]

Hi,

Shut Off Valve seal has been replaced as well as the DV seals.

I have tried fitting one way valves, but they all seem to fail after a couple of weeks.....whether the diesel itself destroys the internals ??