CL500 Engine Starting

[Jumbojim]

My V8 starts well from cold, but it turns over without firing for ages when hot, where should I start looking ?

 

[Sp!ke]

suggest getting the car on a Star machine rather than randomly throwing money at parts.

Saying that, my suspicion would be something like the CPS being faulty.

 

[fast28]

My CL500 started doing this causing the MIL to illuminate once the engine started. Read the engine diagnostic codes and the reader confirmed it was the crank position sensor, replaced it and problem solved.

 

[Jumbojim]

Sorry, but whst is the MIL light. and is it easy to change the CPS?

 

[fast28]

Instrument Cluster

A1e58 engine malfunction indicator lamp

CPS is at the rear of the engine, start from the left cylinder head (left hand side of the car) and go down to the engine block, it's located close to where the bell-housing meets the block.

 

[Jumbojim]

Thanks for all your help, I have changed the CPS, but alas it did not fix the problem and the STAR test did not show any other faults. Strange but true, can you suggest anything else?

 

[BlackC55]

The fundamentals need to be checked firstly.

When it faults is it loosing fuel pressure or spark?

 

[Jumbojim]

Thanks BlackC55( nice car), I had Newtons Merc. Specialist of Chichester use his STAR machine on it. I thought that would show if the SPARKS or FUEL were giving cause for concern. I got a 4 page readout, but the only ENGINE related reading was "ME-SFI-motor electronics 2.8" and that was ticked OK. Whatever that means?
Should I have gone to the Dealership in CHI or over to you in Horndean?

 

[BlackC55]

I know Darren very well. He is one of the best techs on this planet.

He probably needs more time with it to find the issue. The star won't show if it is loosing fuel pressure or a spark.

 

[Jumbojim]

Black55
Darren may be brilliant, but I took an engine problem to him and he charged me about £50 for a STAR run which had no significance, and another £50 to change the CPS which was not the cause of the problem, as there was no fault on the old CPS.
So is it unreasonable for me to feel a little cheated?

 

[fast28]

Sounds like a fueling problem, sometimes the check-valve in the fuel pump fails and lets fuel pressure drop in the fuel lines and injector rail. When the car is turned off the fuel returns to the tank via through the faulty check valve and fuel vapour fills the void in the lines especially where ambient temps have increased, the pump has to push fuel against this vapour which can considerably increase the time for the fuel to reach the injector rail on starting.Fuel pressure is OK once the fuel lines are full. It is likely, though by no means certain that a replacement fuel pump is required if fuel lines are not leaking and the fuel filter has been replaced at the correct service interval.

 

[BlackC55]

Black55
Darren may be brilliant, but I took an engine problem to him and he charged me about £50 for a STAR run which had no significance, and another £50 to change the CPS which was not the cause of the problem, as there was no fault on the old CPS.
So is it unreasonable for me to feel a little cheated?

That's for you to discuss with him.

If I can help just shout.

 

[Jumbojim]

Hi fast 28
What you say makes good sense to me, thanks.