2005 W203 C200 Kompressor Won't Start

[johnsco]

Yesterday the car made two 15 mile trips in the morning.
After a 1 hour break it suddenly wouldn't start.
Plenty of petrol - Fully-charged new battery - Start motor OK - Car cranks over and over at full speed, but will not fire up.
Bother !!
As it turns over, it appears to make weak attempts to fire, but doesn't start.
There is a smell of petrol at the back
So ...
Without diagnostics, I am scratching my head.
I'm not familiar with this engine, but I'll ask here first
I may have to ask Rodley Motors to sort this for me (to my shame)
However - I'm looking for advice:
Am I correct in assuming that when I turn the key to position 2, prior to cranking, this starts the fuel pump running ?
If so, is there an easy place to open a fuel line to check for petrol ?
The metal-braided silver flexible pipe at the back of the engine on the LHS looks promising.
Without a scanner, is it possible to check for a spark ?
The old trick of removing an HT lead doesn't apply to this car.
My initial most-likely guess is the crank position sensor.
Not easy to check without a scan.
Any thoughts please - Before I seek professional help.

[At least, the car now locks OK]
Thanks.
J.

 

[johnsco]

Can anyone recommend a reasonable price OBD scanner ?
Preferably one that Euro Car Parts sell and NOT one that uses a smart-phone.
Thanks.
J.

 

[johnsco]

​

Euro only appear to offer this OBD reader.
Does anyone have experience of it ?
Good or bad ?

Streetwize OBDII Fault Code ReaderProduct Code: 553997350​

 

[Petrol Pete]

Replace the crank position sensor. Buy one from MB direct or at least a Bosch one.

 

[Petrol Pete]

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[johnsco]

Thanks Pete.
Crank position sensor .... That was my best guess.
Is it on the top of the back of the engine (as it was on the E430) ?
If so - I won't be able to do it.
I'm 74 ... Not as strong or nimble as I used to be ... I've no garage where I now live ... And I've no appetite for lieing on my back in the garden struggling to do it.
Is there any way of accessing it from above ?

I'm just going to check to see if there is a vid available.
Thanks for advice.
J.

 

[johnsco]

I can find no vid for the M271 engine.
The American vids only cover the V6 engine.

 

[Bellow]

There is a smell of petrol at the back

Just to be sure - the smell is from the exhaust tail pipes and not a leak underneath the car?

 

[johnsco]

I've just been out and had another go at it.
As the engine is cranking, and trying to fire-up, the exhaust is outputting puffs of smoke and unburnt fuel.
With the key on Position 2 (0-1-2), prior to cranking, I can hear a wining noise, which I guess is the fuel pump running..
I'm not very familiar with this car, and freezing my nuts off outside to learn more is rather beyond me these days.
So - I've bitten the bullet and rung Rodley Motors to ask them to collect the car and do the fix.
I hate being beaten by a job, but .... as we say ..... It's a good man who knows when he's beaten.
Thanks for for help.
J.

 

[Petrol Pete]

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[Gbrowncls55]

+1 for CPS

 

[DrNick]

In a previous thread, someone said that if you crank it and the rev counter kicks up then the CPS is sending pulses. Not sure I believe this but if you crank it and the rev counter resolutely stays at zero, it may add to the evidence!

 

[johnsco]

Thanks for the vid link Pete.
I actually found this shortly after I'd posted - post #7.
The job looks like something of a pig to do.
I'd have to get some additional tools to do it.
If it was summer, I'd have a crack at it.
In winter - It would be a case of hypothermia.
First thing, I'll get Rodley's to run a scan to confirm CPS (or not).
If it's CPS, I'll make sure they get one from MB or a Bosch unit.

 

[Petrol Pete]

I did the CPS on my C55. A 2006 203 c class was never designed to have an M113 V8 engine under the bonnet . To that end MB stretched the nose by about 4cm by using CLK parts...still didn't make replacing the CPS any easier . Even with the aid of my endoscope camera pretty much the whole job is done by feel.

 

[johnsco]

Our W210 E430 (facelift) had the wonderful M113940 engine.
But - The CPS failed on that in year 2015, while my former wife was driving it.
There was a bit more room to work on that car.

 

[Bellow]

.
So - I've bitten the bullet and rung Rodley Motors to ask them to collect the car and do the fix.
I hate being beaten by a job, but .... as we say ..... It's a good man who knows when he's beaten.

J.

Has the car being collected yet? If it hasn't been collected yet....
I'm not convinced the CPS is at fault. They tend to fail when hot and a typical symptom is stalling at a junction with hot engine and low rpm and denying restart until cooled. Also, it's function is to instruct the ECU to fire a plug. That is digital - it either does or doesn't. It cannot contribute to a weak spark and as your car is offering to start then there is some spark there.

I suspect weak spark, over-fuelling, or weak compression one or two cylinders.
To check for weak spark is as normal ignition systems - merely more involved. To check for low compression a compression tester (though smelling the coolant for petrol may indicate a failed head gasket) is required and as both of those require removal of the plugs, over-fuelling would likely be obvious.
If it is over-fuelling, the most likely cause is either a blockage in the air inlet tract or, a failed FPR (fuel pressure regulator). A FPR can fail internally allowing fuel to pass through to the inlet manifold. Remove the connecting vacuum pipe between the FPR and the manifold and if there is fuel present - that's the problem right there.

I'm not saying categorically that a blockage of the inlet tract or failed FPR is the cause of your problem but as they are both so easily checked I'd do that before the car is collected if it hasn't been already. Of those two suggestions, the failed FPR is the more likely.

 

[johnsco]

Thanks Bellow.
Regarding your comment about failure of the CPS - My previous failure (detailed in post #15) did occur, with the engine hot and running, when the car paused at a junction .
On this occasion, the car had completed a 5 mile run without any issues, and had then sat for around an hour before an attempt to restart it failed - and has continued to fail.
The car has not yet been collected.
I would be surprised at a blockage of the air inlet tract .... About 10 weeks ago, I fitted a new Bosch air filter, and have not disturbed anything round there since.
I'm unfamiliar with this engine (but learning fast !!).
Can you point me to the FPR and its vac pipe.
As I understand your post .... If the FPR fails, fuel will be sucked thru the vac pipe into the inlet manifold.
So that - After a failed attempt to start the car, the vac pipe will have petrol in it.
I'll go outside abnd have a look to see if I can identify the part.
Thanks again.
J

 

[johnsco]

OK - I've found a picture of it.
I'll go and have a look.
J.

 

[johnsco]

J.

 

[Bellow]

Can you point me to the FPR and its vac pipe.
As I understand your post .... If the FPR fails, fuel will be sucked thru the vac pipe into the inlet manifold.

Correct - internal failure leads to that.

So that - After a failed attempt to start the car, the vac pipe will have petrol in it.
I'll go outside abnd have a look to see if I can identify the part.
Thanks again.
J

See image below. Yours may not be identical but it will have a cylindrical canister part.
FPRs have three ports. Connection to fuel rail, overspill return to tank, and connection to inlet manifold. One of those could be direct ie, without a connecting pipe. Mounted directly onto the manifold or the fuel rail. Look in that area and you will find it. The one in the image appears to be directly connected to the fuel rail.