Kostas20

Hi all,

I recently bought a 2003 C32 (less than 2 weeks ago) and just returned from a great road trip (Calgary to Vancouver). While parking back into my parking spot the car went into a very rough idle with absolutely no throttle response when I pressed the accelerator. I turned the car off and back on again to the same situation. The car then began to stall out quicker and quicker with every restart until it will now not even turn over.

After much research into the problem on this forum I have discovered that it is most likely a throttle body and/or sensor issue as well as possibly a fuel pump issue. After reading the thread about a previous owners situation with very similar issues and having to replace the fuel pump ($$) I am hoping that is not the problem.

I did a sneaky ecu reset with no change to the problem. (I heard the click so I know I did properly) The last resort before I call a tow truck to have it looked at by MB is a TB reset. My problem is I am having trouble removing the clip to be able to reset the TB and can't find anywhere on the forum instructions on the clip removal. This is probably because it is easy to do, unfortunately for me I just can't seem to get it to disconnect.

If anyone can help me with the steps to disconnect the wiring clip for the TB that would be much appreciated. Also, if anyone has any other suggestions on what I could do to remedy the problem or at even help diagnose it that would be much appreciated as well.

Lenin

How long has it been since you got stuck? Did the car have a chance to cool off and the behavior still the same? Regarding the fuel, there is a schrader valve on the passenger side of the fuel rail. Start removing it and see if any fuel comes out. use a rag. It is not that easy to disconnect the TB wiring clip. I don't have any smart recommendations but I also doubt it will make a difference. This may turn out to be a bad CPS (crank position sensor) but check the fuel first.

Kostas20

It happened yesterday evening, had a couple hours of cooling with still no change. Did not get a chance to try again this morning before leaving for work to see if it cooling down completely makes a difference.

When I get home from work I will see if any fuel comes out when starting to remove it. What would that outcome tell me? (If fuel or no fuel begins to come out)

Lenin

It will tell you if the fuel pump is working or not.

Kostas20

Cold start resulted in the same problem, no change. Didn't get a chance to open the schrader valve, will need to get smaller pliers or pick up the actual removal tool.

C3Duece

can you pull the codes from the computer? that would help a lot.

Kostas20

Unfortunately I don't own a code reader yet. Any suggestions on where to get one and what to get?

Kostas20

I should also mention that I have no CEL and there is "no malfunction" currently either. If that helps figure out what may be wrong.

insame1

The Torque app for android is the best and cheapest reader I have ever bought. You need to buy a Bluetooth dongle for the obd too.

Lenin

Does Torque app read hidden codes? Would it show anything if there is no CEL?

insame1

It reads stored codes. I know that star picks up things it does not but you can also use it to monitor sensors and troubleshoot. check out their site it does many cool things.

Lenin

I know its a cool app even with a slow refresh rate. Just didn't know it would read codes even if the CEL is not present. Thanks for the info.

Speedriven1

Disconnect the tb and turn the key in on position then off, plug tb back in. Sometimes this resets tb

Supgee

Sounds like a throttle body issue, but could also have something to do with fuel pressure like stated above. I know it sucks, but not having any tools or code reader and then asking for help is kind of moot. Even if we gave you the right idea, what are you supposed to do ?
Take it to someone who has knowledge... but first step is... #1 read codes #2 measure fuel pressure

Kostas20

Sorry for the delayed response, didn't get a chance to do anything until today.

I had the entire schrader valve removed at the end of testing it with the engine trying to turn over. Not a drop of fuel came out.

I picked up a code reader and the only code it picked up is P0442 - which I believe is "Evaporative Emission Control System Leak Detected (small leak)" My guess is probably due to the lack of fuel getting to the engine??

I believe this is looking more and more like my fuel pump is toast. I found instructions to replace the fuel pump through the back seat and after lifting up my back seat it is indeed accessible.

Anyone have any other thoughts on what my problem could be or what else to test/look in to.

Also, the fuse for the pump is still good, unfortunately.

Lenin

If no fuel came out when you put the key in position 2, then the fuel system is not moving any fuel into the rail (dahhh!). Double check the fuses. Just to be sure. It is fuse #4 of the rear SAM in the trunk.
I would then open the passenger side access opening to the pump and test the voltage on the pump while the key is in position 2.
Also, if you are not sure what you are doing, and/or you have some funds available to take it to a qualified mechanic, do it, since this can be so many other things. But if you want to continue, I'm sure that the forum will help you.

Kostas20

This past weekend I tested the voltage coming to the pump. When there was in fact voltage I was a bit depressed thinking of the cost of having to order a new fuel pump this week. Before I walked away from the car I plugged the wiring harnesses back together. I hear a faint purr from what sounded like the fuel pump. I went to the front seat and decided to give it a shot and try starting the car again. To my immense surprise, it started up almost immediately!!

I had learned to begin resenting the car after such a major issue less than 2 weeks after purchase, but that first stomp on the pedal after it came back to life and I fell in love all over again.

Not sure how I got so lucky, the connections looked fine, no corrosion at all. I am getting 3 codes now though. P0442 (had that earlier) and now P0460 "Fuel Level Sensor Circuit Malfunction" and P0453 " Evaporative Emission Control System Pressure Sensor High Input "

I did a bit of research on the codes through the threads but didn't find much. Are these to be seriously worried about? Should I take it somewhere? I still don't have a CEL so I am assuming they can't be too serious of an issue.

Lenin

That's good news. The only problem is that you don't really know what caused the issue and if it comes back, you can get stuck miles from home.
You should clear the codes and see if they come back. Also consider replacing the fuel pump. You can get an OEM or aftermarket for under $150.

Kostas20

So, unfortunately this issue has returned and this time the car will not turn over.

I had it towed to a garage since it quit on me while not at home, and I do not have the tools or time to swap the pump myself anyway.

Lenin, as the forum has repeatedly pointed out, you were right! Thanks for the assistance before and I am hoping you can help me out again.

The same issues happened to me as back in the summer, car would not turn over and no fuel was getting to the engine. The garage first checked the relay and said it started and ran great. They took it for an extended road test and on the return it would not restart after sitting. They said they "knocked" the fuel pump and it started again, obviously the fuel pump is on it's last legs.

They told me the pump was going to be 2000 CAD and about 300-400CAD in labour, as you said Lenin, the pumps can be purchased for much, much, much cheaper. I found this one below:

https://www.rexbo.eu/pierburg/fuel-p...00717&at=11221

I am hoping someone can let me know if this is correct, to me it looks right.

One other concern I have is the following, I remember when the car would not turn over I could not hear the pump whirl with the ignition in the last position just before starting. Although I knew when the car would turn over after a couple attempts because I could hear a whirl before turning the key all the way.

This was heard on the driver side fuel tank access point, from my research thus far the pump is actually located on the passenger side. Is my research incorrect? Could the whirling pump sound just be traveling through the tank for me to hear it on the driver side? Or is the issue potentially something else as well?

Any help is appreciated, hopefully I am explaining everything adequately.

Lenin

Feeder: 7.21088.62.0
Main: 7.22013.02.0

Not sure what you are hearing/not hearing but if your car is already at the shop, maybe look into replacing both the main pump (on the passenger side) and the feeder pump (on the driver side).

Kostas20

The part numbers you posted are confusing me a bit.

The feeder part number matches what I thought was the main pump and according to the pierburg catalog, the part number for the main pump is another main pump for a BMW E39.






When looking at the Pierburg fuel parts catalog for the C32 it lists two part numbers:

7.21088.62.0 which is what I thought was the main fuel pump

https://www.rexbo.eu/pierburg/fuel-p...00717&at=11221

7.22466.93.0 which it looks like is the fuel sending unit

https://www.rexbo.eu/pierburg/sender...00268&at=11221


As you can see I am a bit confused to the two part numbers you posted. Based on what you said about swapping the sending unit and the pump this is insanely cheaper than what the garage quoted me. If this is correct I can get both for around 300CAD.

Kostas20

Update: I believe I have finally figured out the C32's in-tank fuel delivery system. Hopefully this will be useful for others in a similar, unfortunate situation. I have pieced this together with the help of multiple other fuel pump threads and Lenin's extremely helpful responses. Praise should also go to Gramma_Benz who contributed to multiple fuel pump issue threads from a couple years ago that were also a huge help in my research.


Passenger side fuel compartment contains a fuel pump assembly, which holds a main pump and a smaller aux pump. The aux pump feeds the main pump. The pump assembly does not provide power to the either pump it seems, the only component built directly into the pump assembly is the passenger side fuel lever.
This pump assembly can be found here:

https://www.rexbo.eu/bosch/fuel-feed...00267&at=11221

The two pumps that are housed with the pump assembly on the passenger side can be found here:

Main pump:

https://www.rexbo.eu/pierburg/fuel-p...13020?c=100717

Aux pump:

https://www.rexbo.eu/pierburg/fuel-p...00717&at=11221

Now what I myself to believe to be the main culprit for our C32 fuel delivery issues based off of other threads and my current situation is actually the driver side fuel sender unit which can be found here:

https://www.rexbo.eu/pierburg/sender...00268&at=11221

The reason I saw this is that others have said they have replaced the pumps with no progress, only progress is made once they change the two fuel pump assembly and the fuel sending unit. Since the fuel pump assembly only holds the fuel pumps and has a level unit (the power for the pumps is from the sending unit and wiring that runs from the driver side to the passenger side inside the fuel tank) it leads me to believe that if your fuel gauge works then you can save your money on the fuel assembly unit.

Since my car is at the garage already I am going to with the main pump, aux pump, and the sending unit. The garage quoted me 2000 CAD for the fuel pump. Through the links I have posted I can get the main pump, aux pump, and sending unit for about 320CAD shipped from the UK.

I will let everyone know how it goes, Lenin or anyone else please chime in some point today if anything I have said looks off. (I am going to order the parts later today)

Lenin

https://www.rexbo.eu/pierburg/sender...00268&at=11221 is just the connecting inside-the-fuel-tank fuel lines. Very unlikely you would need this unless someone was messing with it before or during the install.

https://www.rexbo.eu/pierburg/fuel-p...00717&at=11221 is the pump for the sending unit located on the driver side.

https://www.rexbo.eu/pierburg/fuel-p...13020?c=100717 is the main pump located on the passenger side.

To be on the safe side, replace both the main pump and the aux pump and get the two new rubber seals for the fuel tank. They now come in green color. The seals will seal the tank and will eliminate the gasoline odor inside the car.

scboost

lenin so is there 3 pumps?? main pump on pass side, baby pump that fills the pump housing and sender pump on driver side? what is the part number for the baby pump?

Kostas20

I may be wrong but I am pretty sure that the aux pump and the main pump are both on the passenger side, only the sending unit (link below) is on the driver side.

https://www.rexbo.eu/pierburg/sender...00268&at=11221

From the image shown in the link below you can see the two different units. One that houses the two pumps and the sending unit that powers them.

http://www.mbpartsworld.com/showAsse...rimLevel=20605

Additionally in this thread there are pictures that show the opened passenger fuel sending unit that houses both pumps.

https://mbworld.org/forums/c32-amg-c...low-rates.html

I am not saying that this is correct completely, just showing why I think this is the situation. Please correct me if I am wrong.