carigmbamg

My C32 started yesterday and ran for about 20 seconds before dying. Now it just cranks and never starts. I can smell a slight gas smell from the exhaust, I have no malfunction, fuel pump fuse is OK. I have searched the web for help, but nothing too close to this. The B service was just done last fall, but the car sits a lot these days. It has less than 50K on it. I live a long ways from any dealership, so help would be greatly appreciated.

inflectionpt

check your cps (crank position sensor).

Budget Baller

CPS

Get an OBD reader. There's probably a stored code.

carigmbamg

I am getting my OBDII out to get any codes, but was wondering how to "check the cps". Is there a way to do this without installing a new one?

Budget Baller

Usually the CPS going out will throw a code which is enough. But, there is no way of that I know personally to test the CPS other than to change it.

When my CPS went out there was a stored code.

carigmbamg

Got ScanTool OBDII connected and got no logged or pending fault codes. The timing was registering as -54.

lizardjack

Can you actually hear the pump when you switch the ignition on?

carigmbamg

Assuming the fuel pump is in the back, I opened the rear seats up and as I turn the key just short of starting, I can hear what sounds to be a relay in the trunk click, but no whir of a pump. I checked the fuel pump fuse yesterday and it looked good. I unseated and reseated all the relays in the trunk too.
I thought that I read in a post, that if the CPS was bad that it would disable the fuel pump. Is that true?
I have found a Bosch 0261210170 Reference Mark Sensor (Crank Position Sensor) on Amazon for $45.
Further help is appreciated. Thanks

lizardjack

Most likely the pump is dead or connector on the rear SAM melted.
CPS has nothing to do with the pump, it does manage the injectors though.
Check for power supply to the fuel pump. I cannot believe that both main and aux pumps went down at same moment.

ScottW911

What was the outcome?

It sure sounds like the CPS to me. I had the same issue a few months back.

I had an interesting side effect from replacing it here:

https://mbworld.org/forums/c32-amg-c...sion-jerk.html

Read through it and you will find the cheapest place to order a CPS and the codes the car should throw.

carigmbamg

Just got the CPS in the mail today, still waiting on the E8 torx socket to arrive, plus I have to tile the bathroom walls and floor before I can start (says the boss). I will post as soon as I can get the car up on jacks and try my hand at CPS surgery.

lizardjack

Waste of time/money IMO

carigmbamg

Lizardjack, the tank was replaced two years ago under extended warranty (just before it ran out), so hopefully it is not associated with the fuel pumps, but doesn't mean that it couldn't be.

ScottW911

I paid an indy $100 to install mine. It turned out to be some of the best money I've spent. It took the pros 2 hours and several devices I did not own, to get to the CPS. The actual fix is easy. The location sucks.

Good luck to you.

W203Ramos

could be anything but we've all gone through this and i'm pretty sure it's theCPS . good luck

lizardjack

Those two lines above are sufficient for me to come to conclusion that this is the fuel supply issue! If you are confident with your newly installed pump, then check relay, fuse, connector on the rear SAM.
CPS in 99% dies gradually and it always shows it's symptoms when the engine is hot.
Anyway, good luck to you. And please post the results upon resolution.

lizardjack

Do not take the offence but if you'd have more clues to engine management system you'd never tie CPS to engine load equation algorithm.
CPS is simple gauge that "tells" ECU there and at which phase pistons are located to enable most efficient fuel injection and ignition timing.
It's either work, or doesn't!
Most likely, in your case the technician who you had to install it for you fixed (accidentally) bad connection on the throttle body for example or any other coincidence.

W203Ramos

replacing the cps is a good place to start instead of assuming that your fuel pump is dead or rear sam is melted we try to be optimists here on the forum but based on your description seems plausible that.... cps it is. symptoms have nothing to do with the engine being hot or cold, it just so happens that the car has to be running first in order to experience the symptom....usually.
John

carigmbamg

Update, fired up for a second today, but died and just cranked. Flexible 1/4" shafts now delayed until the 11th. So much for good weather to do the job this weekend. Back to tiling.

Beaker

I've had both my CPS go and my fuel pump go, will tell you what happened for both..

CPS - The car would literally just stop in the middle of the road and lose all power. Then it would start up again sometimes the 3rd time sometimes the 30th attempt. I was told the heat did not help trying to restart it but once it started again it usually would be fine again for that entire trip. I got a CEL code reading to know it was the CPS. I drove the car for over a week though even though the CPS was dead but when the car dropped dead randomly in the middle of a highway I had a enough. It probably stopped working 3-4 times, thankfully these were on quiet streets and not major roads.. nothing leading up to when it just stopped and would not crank over again (however it always did 20minutes - 2 hours later at some point)

Fuel Pump - The car again died without warning.. this time though I could not get it started. The car would crank over for 5-10 seconds sometimes but idle very rough, at about 500 not even 700 then just die out. Was obvious it was a fuel supply issue going on.

So from your first post I would 99% say it's a fuel issue and not CPS related.

mbz03

Cps it happen to me too I did it, it was a pain on the *** good luck

carigmbamg

OK, installed the new CPS today and NO luck!

I checked to make sure that I had spark and I was getting spark. Relay for the fuel seems to activate when trying to start. Thinking of renting a fuel rail gauge to check for pressure. Thoughts?

lizardjack

Just push the needle of valve on the fuel rail. I am sure you will not have any pressure at all.

carigmbamg

I did push in the needle and no pressure, but the car was not cranking at the same time. Does the fuel rail stay pressurized? If so, I would agree that fuel supply is the problem. I will check voltage at the pumps and continuity on the pumps.

lizardjack

If the fuel system works flawlessly, there should be a pressure remained in the line all the time.