Kris0003

Hey Guys, I'm really struggling with my CLK at the moment. Wednesday night car ran really rough and engine light came on, ran the codes p0366 came up, thought ill order CPS online and replace, Thursday morning just about to do 10min school run, went to start car cranked long time did not start, so thought leave it order new cps. Installed new cps Friday went to start car and same problem, cranks but will not start. I've checked all fuses and relays for starting, tried jumping battery and no change.

Here's a video of it trying to start:

Really grateful of any advice you can give and view the video see if it's something you have encountered before? Like with all our cars this is keeping me awake at night thinking the worst

I'm going to get it booked in a garage this week so I'd like to have some idea what's facing me.

Thanks for viewing my post

Kris0003

Glyn M Ruck

Check fuel pressure at the Schrader valve on the front fuel rail that connects the injectors to one another. Should be > 3.8bar or 55psi while cranking.

To start require:

1) Start enabled via EIS etc.
2) Fuel
3) Air
4) Spark at the right time.

https://mbworld.org/forums/c-class-w...t-process.html

Anker

I believe the tach should show movement during cranking if the CPS is working properly. You have zero movement, so I suspect it isn't working.

Rudeney

i don't believe the tach registers until the engine is running. However, if you have a scan tool that shows the engine speed, it will register while cranking.

Anker

Sometimes it is hard to remember whether something applies to my Porsche or my CLK. :-)

C3Duece

correct...tach should bounce until it starts. Some non OEM parts can show up DOA.

Kris0003

Thanks all for the replies so far. Quick update - new cps is Bosch direct replacement for the Oem one I took out. My sister has the slk with m271 engine and exactly same cps I removed from mine so tried her cps in mine and the same result - crank no start. I've charged the car battery overnight as the cranks had left it on its last legs, I'm just waiting on a fuel pressure test kit now, once delivered will test the schrader valve.

I've also took back seat out so I can hear the pump engage well the few second hum you hear. Can that still make this noise if broken, what sort of faults can it be if the pumps okay?

BenzAMG99

why don't you fill the tank up?

Glyn M Ruck

Yes the pump can still run but not produce enough pressure if the filter on it's intake is clogged. Your car is right at changeover point. You might have an in tank filter or an external filter that contains the pressure regulator.

You are going to have to check whether or not you have an external filter.

Don't fill the car up if you have an in tank filter or you are going to have to drain some fuel before removing the pump/level sender unit to replace the in tank filter.

Kris0003

I believe my filter is external to the tank behind the rear wheel arch plastic? Pump and sender are under the rear seat under bolted down compartments? Is this correct?

Glyn M Ruck

Your car could be either. They changed from external to in-tank in 2006. If it's external you should see it above & at the rear of the LHS of the saddle tank behind the LHS drive shaft to the wheel. If in-tank it is in the sender unit with the pump under those round covers under the back seat.

Kris0003

ive run the pressure test and the gauge was flickering between 50-60 psi during cranking. Also checked all spark plugs and they are all fine.
In the process of elimination what is next for me to check when the car is still not starting but cranking?

Rudeney

It might be time for a proper diagnosis with SDS to pull codes and check the function of the CPS, ECU, etc.

Glyn M Ruck

If the aircleaner is not clogged solid & you don't have a blocked Cat I agree with you Rodney. This car has the M271 engine so it's coil on plug. No coilpacks to fail, only single coils & then you would get a 300 misfire code. My worry is that the timing chain might have jumped that is so common on this engine if you don't listen to them carefully & react immediately you hear a slight rattle at cold start that shuts up the minute the oil pressure rises.

Kris ~ how many miles has the car done? Are you able to do a compression test on all cylinders?

I sincerely hope I'm wrong but that engine is making weird induction noises while cranking. Once the valves are bent they will crank over just fine.

Kris0003

mileage is just approaching 70,000. This is worrying, i will see if i can get a compression test on the cylinders . Wouldnt there be signs the chain was on its way to snap or fail leading up to jumping? I guess this is catastrophic if it has jumped and damaged the engine? Is the repair expensive would be cheaper to replace engine with another low mileage one?