mfx999

Ok so last couple of months my car (c200 kompressor 2001 stationwagon) kept dying out on the road kinda randomly from time to time, some times more often than others. I changed the fuel filter maybe a month ago but the problem still accured, now im thinking the fuel pump. Is there any easy way to find out that it is the fuel pump that is actually the problem? one friend of me told me i could unplug the fuel hose from the engine and try to switch on the ignition and see if any gas is coming out from the house, if not, the pump should be broken.

Thanks

B3Hulk

you should get a fuel pressure tester , its a lot easier and safer and barely cost anything ($20) from your local auto store.

Here a video explaining the process

C230 Sport Coup

You'll have a shrader valve on the fuel rail, that's where you check the pressure. I bought a pressure gauge from Harbor freight, but later found out I could've gotten on for free from my local auto parts store. They loan tools.
Not sure if they do that where you live. Another thing to look at would be the crankshaft position sensor, or the cam sensor....but each of these would likely throw a code and give you some indication.
Read the codes. You can bluetooth OBD reader on ebay for like 10 bucks and then get the app Torgue for your phone for free to read the codes.

mfx999

Thanks for help!, seems like it was the fuel pump that didn't want to co-operate anymore, changed it and now it works just fine

RWDlifer

Fuel pump failure is insidious on these cars, I personally think everyone who has over 100k should preemptively change it, or risk ending up stranded on the side of the road at 2 am in middle of night.
Your fuel pump WILL fail. Where will you be when it happens?

C230 Sport Coup

Glad you got it taken care of! Mine craped out at about 210k miles. It pretty much went all at once while I was on my way to work. I started noticing it about 5 miles before I got there on the freeway I had no power. I managed to nurse it into the parking lot and then had it towed home. I did the work myself . But not too much later it failed again because one of the hoses popped off. If you did the work yourself I strongly recommend going back in and putting tie wraps on the hose connections around the outside, and I used a special tie wrap tensioner to pull the tie wrap as tightly as possible and also I paid attention to the type of plastic that the tie wrap was made of so it would not be affected by the gasoline. So all is well now.

mfx999

I did the work my self yes. Hoses popped off? that sounded weird, i think i connected them properly but who knows what could happen.

LexBrett2

So the fuel pumps are a weak spot on our cars. I'm constantly watching my fuel pressure since I'm running nos, see pics.

Is the fuel pump just under the passenger rear seat? Seems like changing it out would be too bad??

C230 Sport Coup

Well, 210K + actually just checked my service records, somewhere north of 220K actually, isn't bad. I wouldn't call that a weak spot after 14 years. When you pry the hoses off the old pump, you stretch the plastic a little doing it...be really careful you don't damage them. Mfx is so casual about the whole thing. Ha!

Anyway, no it's not too bad of a job. Yes, it's under the passenger side (ie right for all you limeys with your passenger side on the left).
But pretty scary with all that exposed fuel while you are working.
I mean one little spark...boom!
I tried to find a pump to remove the fuel, but couldn't really find a decent one, so I just skipped it, I had about a 1/2 tank.
I bought a fire extinguisher, which the guys on the forum got a kick out of since, if it did ignite, it would probably go up so quick I wouldn't even have time to deal with the extinguisher. Also static electricity could be the end of you! Be super careful.
Avoid using metal tools, wearing clothing that might cause static, or even moving around too much. Ground yourself to the tank if possible. At least put your hand on it
frequently to dissipate any stored charges before they build up enough to cause a spark. Open all the windows and doors, maybe even put a fan to keep the fumes down. The lower explosive limit of gasoline is only like .1% in the air vs. methane which is like 5% !

So after the fact, my mechanic pointed out that I should have put the tie wraps, said he always does or that the pressure may cause the hoses to pop off later.
So after the pump was replaced all was well, and suddenly about 2 weeks later....poof...the car dies. Luckily right around the corner from house. I went to the hardware store and bought a tie wrap tensioner and tie wraps.
Lucky for me, my mechanic there had already put me onto the hoses staying attached issue. Thanks *****!

The other thing you need is a special tool to take the cover off.
No one sold one locally. BUT Autozone has one to loan, and maybe even the fuel pressure gauge as well. But for certain Oriely has that.
Stupid thing I'd already returned it and had to go borrow it 2nd time, arrgh. Like 5 miles away.
Now I own the tool...still unopened in the package, the Lisle one.
Keep it in the trunk with my other tools,and the tie wraps etc. just in case it pops off again, I can get in there.
To relieve the pressure in the line pull the fuel pump fuse and crank the engine....it will sputter and die, and the pressure will be gone.

The other side has the sending unit thing, with all the hoses and a fuel level sensor for the other tank. They say it's best to replace both at once, but that's an expensive piece and has all the wiring and hoses that need to be fed over the other side, a PIA job.

FYI, I used a genuine Mercedes pump at over $200. Yeah, you can get one much less expensively, but I didn't want to risk it with something so important.

Dan Sang

I have a similar problem too. First it stalled and stopped completely. The battery /alternator light went off and I bought a new battery. Went well for two weeks then started stalling again. Checked the alternator with a mechanic and said it was fine. But it still stalls or has a hard start. I read your comments and kinda thing it's the same problem with the fuel pump. If anyone has a clue I would appreciate. Thanks