It's been said that the filter was replaced like 4x in this thread.

 

^ Yeah thanks Matt the fuel filter has deff been changed and I doubt it defective since its been a few months and this cold start has been since its gotten in the 30s. Now how would I go about checking the pressure on the fuel pump. Where does the thing hook up to?

 

How do you check the pressure of fuel pump on these cars? Do I have to remove the seat to access the stuff?

 

There is a port at the end of the fuel rail - you will see a small cap looking like the tire valve cap. Remove that cap and you can screw a fuel pressure tester on to that port.

 

Is that the thing under the engine cover like where you release pressure for when your'e changing the fuel filter?

 

I just had the Camshaft thing done at the dealer since they were leaking so thats all good now and the car is still starting hard everytime I turn it on. It always takes me like 3 tries to get the car to run. Here is a video of me starting the car. Its been fully warmed up prior to this, only turned it off for few min to get something in the house.



It takes this long everytime and sometime I have to crank it 3-4 times.. Been like this for over a month since the temp dropped.

 

yes, that's it. It looks like tire valve. Remove the cap and attach fuel pressure gauge and read the pressure before starting. I have a feeling the fuel filter is not holding the fuel pressure. I believe the pressure regulator is integrated as part of the fuel filter. Fuel Pressure test would confirm/disprove my theory.

or, put the key in ignition turn to position to 2 (don't start), hold the key there for 3 to 4 seconds and let the fuel pump pressurize the system, then try starting the car. See if that helps.

 

Get this sorted out yet? My 07 started last night on the 3rd key cycle, and would not start at all (tried 3 full key cycles, then gave up.) this morning. I know mine is a different engine, but acts the same as yours does in the video.

 

Oh crap John - any codes on Star?

 

No codes in STAR Battery voltage is 12.29V, so I am going the leave the car on trickle charge all day, while I am at work, and see what happens. I am going to stop and get a new CPS, as I suspect that may be the culprit.

 

12.29V should still be enough to start it. Damn that sucks.

 

Agreed, but it seems sometimes these cars are a little picky about voltage. I know it has started in the past with even less voltage with no issues. Surprised my only 4 year old battery is that low though

Picked up a CPS at the stealer, $50 later.

 

It might be that low due to all the starting attempts, no? Doesn't it cycle the starter for 15 seconds each time to try? This would be the first CPS failure of a 07 I've read about on here, but you are at unusually high mileage over a lot of the others. What are you at now?

 

Matt, yes it cycles the starter for 15-20 seconds on it's own then shuts off. The night that is gave me problems first (last Friday), it took 3 cycles before starting, but then I drove ~1 hour/40 miles, so it should have charged almost completely. Then, Monday morning I tried 2 complete cycles with no start, and left it as is. Then, ran STAR on it this morning. One part of STAR said battery voltage was 12.6V, then 12.1V in another spot. I measured it with my DMM at 12.29V direct at the battery.

Yep, I may be the 1st 07 C on here with a bad CPS, but I see failures on other models of similar mileage.

I am just shy of 83K miles now.

 

CPS is probably a good call.

 

Hey, No I havent had a chance to fix it yet, I've been pushing my luck and driving the car like this. It never fires up on first try for me anymore, 2 or 3 cranks later it starts and off I go. I don't think its anything with the engine more like something ignition or fuel related. My battery is fine too. So you are saying a new CPS fixed your problem John?

 

Don't know yet if the CPS will fix the problem. Bought the sensor yesterday, and just tried to replace it, but it is VERY difficult to get to. You have to sit on the motor/radiator support, and the sensor is buried at the back of the engine, and I barely can get my hand between the cylinder head and firewall. I'll try again this weekend when I have more time.

Charged the battery all day yesterday, and took it off the charger last night. Voltage this morning was 12.89V and the car still wouldn't start, so battery is not the issue.

 

That damn CPS is even more difficult to replace with the M272 quadcam heads.

 

Yes it is. You can't see the sensor, it is going to be one of those replacement by feel jobs.

Before I replace it, I am going to double check fuel pressure. My buddy that borrowed my fuel pressure tester is dropping it back off today.

 

Damn John, I hope you get this sorted soon. I know you must be highly frustrated.

 

John, I have replaced the CPS on my '07 C280. I removed the air filter assembly, then MAF, then the plastic elbow that comments MAF to throttle body. Once those parts were removed, I could see the CPS connector while standing next to the battery and looking towards the CPS area. Standing near the battery and putting the left hand from the trans dip stick area, throttle body, start feeling for the connector, you won't be able to put 2 hands in there. So, you will have to be very patient and take your time. While putting back the screw, be careful not to drop the screw :-)

 

pcy - were your symptoms the same as John's?

 

Yes, it is frustrating, especially since my Jeep is dead too. I don't like having any of my vehicles non-functional, and I have 2 of the 3 down now, and my wife is without a running vehicle. Plus, the Mercedes is scheduled for the body shop Monday morning. Since I just changed jobs, I can't take a day off to take care of it. It is equally frustrating, as the Mercedes shouldn't be this damn unreliable. Oh well, hopefully I'll get them both sorted out this weekend.

PS: Still have no plans of abandoning it anytime soon, I am still happy with it considering all that has happened lately.

 

I was gonna say something about my 05 vs your 07 reliability but as soon as I do oil will explode out of my adapters into my ECU and cost 3 billion dollars to fix.

To be honest, my car is running quite *****ty lately, too. I'm getting a ton of things done today (is in the shop now) and hopefully it will be sorted.

 

Thanks for the tips Didn't consider trying from the passenger side, since the CPS is on the driver's side. But, I did notice there is much more room on the passenger side then the driver's side. The whole dropping the screw thing is what I am most worried about. When I replaced one of the camshaft magnets, I dropped one of the bolts, and it didn't drop out So, I had to get a replacement from the dealer. A couple of weeks later my wife found the bolt in the driveway Trying to source a magnet insert or magnetic E8 Torx socket.

Since I wanted to pull the MAF to clean it anyway, I will try your method.