Poor starting on my w203 C220 CDI O3 Plate

[carlh2269]

This past week the car has been getting more difficult to start. Cranking over is good and there are no fault codes. When it does eventually start, the engine and performance is normal. You can switch off the engine and immediatley try to start again and it wont for about 10-15 secs of constant cranking over. There is plenty of fuel and the sympton's are the same for hot and cold starting.
Any ideas would be a great help.

 

[ajlsl600]

when was last time fuel filters were changed?

 

[Stability]

Check for air leakage on fuel lines via transparent pipes from filter whilst cranking.

Injector leak off test would be advisable aswell

 

[carlh2269]

when was last time fuel filters were changed?

It was serviced some 2 months ago and it has been okay since then until about a week ago. All the filters were changed at its last service.

 

[ajlsl600]

battery good, getting full cranking speed? issues with crank speed sensor..

 

[Rappey69]

heck for air leakage on fuel lines via transparent pipes from filter whilst cranking.

Injector leak off test would be advisable as well

+1 for the above ....

 

[carlh2269]

The cars at the garage and they say it could be the high pressure fuel pump.
Any thoughts!
The engine runs fine once its started so if its low fuel pressure whilst cranking wouldnt there be a malfunction code?

 

[mersum1es]

The cars at the garage and they say it could be the high pressure fuel pump.
Any thoughts!
The engine runs fine once its started so if its low fuel pressure whilst cranking wouldnt there be a malfunction code?

During start, low pressure does not trigger a code. However you can monitor it via live data of SDS. If its lack of pressure, usual culprit it, like said, o-rings of return lines, back leak of injectors. Yes, it can be hp-pump too, but it will be much harder to pinpoint. Sometimes it will leak outside when it is easy to see, rarely inner leaks may happen but then it usually cause troubles at high pressures too. In general, leaks and starting problems start at low temp, then escalate to higher engine temps.

So, is there air bubbles in return lines? How much injectors are leaking back?

 

[carlh2269]

I've checke

During start, low pressure does not trigger a code. However you can monitor it via live data of SDS. If its lack of pressure, usual culprit it, like said, o-rings of return lines, back leak of injectors. Yes, it can be hp-pump too, but it will be much harder to pinpoint. Sometimes it will leak outside when it is easy to see, rarely inner leaks may happen but then it usually cause troubles at high pressures too. In general, leaks and starting problems start at low temp, then escalate to higher engine temps.

So, is there air bubbles in return lines? How much injectors are leaking back?

I've checked further and it looks as though the pumps in the tank could be playing up.
I'm looking for wiring diagrams now to take it further.

 

[umblecumbuz]

Wonder what makes you suspect the tank fuel pump?
(Saddle tank on this model).

 

[carlh2269]

Wonder what makes you suspect the tank fuel pump?
(Saddle tank on this model).

I've done a bit more investigation and it seems that there are no volts at the fuel tank pump.
The timer relay, in the boot, doesnt seem to work as it should so there could be no volts across the coil.
I've yet to look into this one.