450 SL in Denmark

Hi,

I am not too sure that it is the same with the US fuel vapor evaporation system, but I do not hear air noises when I open my tank. Christian can surely tell more.

What I hear more often is that dirt collects in front of fuel sieve in tank when pump sucks out fuel. Then you can drive a while and dirt blocks fuel outflow. You sit and wait, in the meantime dirt dissolves in fuel again. Then engine runs suddenly as usual.

Hi Peter,
I think you should check what Volker wrote.

Just install a fuel pressure gauge instead of the cold start valve and let the pump run permanently for an extended time.
 
Regards
Norbert

...just diconnect  the ventilation line from valve near the rear axle and see if something is changing ! You can also check if the line to the gastank is free with compressed air !

Hi everybody,

Thank you for your valuable input. I have picked up the car today and have taken it for a longer run in order to try to replicate what happened the other day (petrol coming out of the filler neck, engine running rough, etc.). The mechanic has provisionally hooked up another ECU (0280 002 007), which is for a complete other engine, I know (3,5 L), but we did that in order to ascertain that it is not a clogged fuel filter, fuel tank strainer, vent system, etc. and the care is running again. It is not buttery smooth as I suspect that this provisional ECU makes the car run rich. This is also confirmed by a CO measurement. Fuel pressure is stable at 2 bar.

The tank vent system has been looked through and there is nothing clogged and after a good run there is now only a very subtle "swoosh" when I open the tank cap. Nothing is spilling out.

Could it really be the ECU? Something is indeed pointing in that direction.

Volker, is there any way for you to test my ECU if I send it to you? - and if it is indeed bad, do you have any good xxxx xxx 005 on your shelf that I can purchase?

Best, Peter

Hi Peter,

I have asked Christian to answer your question of fuel spilling out of tank neck as I am not too familiar with US tank evaporation system.

However it is for sure that this was not caused by your ECU. I recommend that you find that fault first and if it is found switch back to your original ECU to verify if all faults are gone. Of course I will further support the donor of flowers if your fault continues. And yes I have a proper ECU as well.

Hi Volker,

That sounds good. The theory of the mechanic is that because none or only a small amount of fuel was consumed by the engine, the vast majority of the fuel was sent back to the tank through the return line, thereby causing excessive turbulence in the tank.

I will go for an afternoon/evening drive and see what happens. As explained, the ventilation system, including the valve under the car has been checked.

Br. Peter