W124 E280 starting query

[ap999]

My E280 owner's manual seems to suggest that when switching on the car I shouldn't need to depress the accelerator.

However, since buying the car, it has always required several attempts to start it and always required the accelerator to be depressed (sometimes fully) before it would fire into life. This occurs for both hot or cold starts.

Once started, the engine idles perfectly and moves through the rev range smoothly with no misfires. There are no stalling symptoms either.

Any pointers to what I should be checking in order to improve starting?


Thanks

 

[GP801]

The manual is correct. No need to depress the throttle when starting. Something is not right. Unfortunately I am not that technically minded but someone will probably point you in the right direction

 

[grober]

Could be several things. first- how old are your spark plugs? I would change them for new- can make a huge difference. They are not that expensive on that model I would recommend NGK BCP6E/6ES available in Halfords. Other possibility is your fuel pressure is falling rapidly when standing or taking time to reach operating pressure on starting the fuel pump- when was the fuel filter changed last?

 

[kth286]

yes - pehaps fuel pressure regulator diaphragm is slightly ruptured.

 

[ap999]

Thanks all.

Will try plugs first as a first step as a full service was over two years ago.

However, seeing as it drives fine, I think your diagnosis of the fuel pressure needs further investigation.

Is it easy to check the condition of the fuel pressure regulator? Secondly, where is it located?

 

[grober]

The fuel pressure regulator is a circular/cylindrical unit located at the end of the fuel rail that supplies the injectors. It will have a flexible black pipe attached leading to the inlet manifold to sense inlet vacuum. Part no A 0000781889---- not an inconsiderable £85 from MB. BUT CHECK with your VIN number. There is also a pressure take off point on the rail to check fuel pressure which I would advise an injection specialist should be able to test for you before you splash out on a new one