c124 poor tick over and fuel evaporation system fault?

[glynandrews]

Hi Guys,I wonder if anyone could shed some light on this problem as its driving me mad!I have a 1993 ce220.The tick over is too slow and as its a bosch system has no means of adjustment.I have replaced the air flow meter which ade no difference whatsoever!I have traced through the vacuum pipes and after many hours found that a vacuum pipe is attached to the fuel evaporation system on the n/s inner wing.If i remove the vaccuum pipes and connect together it ticks over almost perfectly.The only problem is that this then seems to cause vacuum issues in the tank resulting in a hiss when the cap is removed.There is a bad smell of fuel in the car which seems to stop once this is done.I have tested the valve on the fuel evaporation system valve which doesnt ever seem to get any voltage?The question is where should the voltage be controlled by,its a new valve too just in case.I have found that if i connect the pipes back to front its almost perfect?Bizarre and doing my head in!!I have bown down the pipes to the tank and all seems clear.Could i run an ignition controlled live to the valve?Much baffled and any info gratefully received.

 

[kth286]

the purge valve on the the inner wing should pulse at approx 2 beats per second to allow the fumes from the petrol tank to be drawn into engine and burnt.

You should hear it and feel it with hand.

But, the conditions have to be correct for the valve to be pulsed.

At idle the engine has to be fully up to temp for example.

The pulse is controlled via the main engine ECU.

You should get the whoosh when petrol cap is opened.

Is the engine getting fully up to temp ?

 

[glynandrews]

Hi and many thanks for the reply.Yes the engine is getting fully up to temperature but the valve doesnt seem to be getting any voltage?it doesnt click at all.It is a new valve and definately works as i tried sending a feed to it.