My C32 Days are over.
- I dont think it is a fuel pump because my car have never stalled out in the past ,no problems starting previously, no check engine light, no sudden loss of power while driving.
- I dont think its a battery because everything else is functioning.
- May be Starter?
- May be Alternator?
- May be CPS or fuse.....
Any help will greatly be appreciated.




A good simple test is to squirt about a tablespoon of fuel into the throttle body. Crank the car and if it coughs a few times, then you are likely not getting fuel to the injectors.
Note it could be many other things, like a crank position sensor (CPS) that needs a replacement. Bad CPS would not give spark. These usually fail when warm and come back when cool. But you never know.
I will have a friend come by later on today and run a compression test for me, hopefully that will tell me if its something with fuel pump or compression.
Are there any fuses or relays I can check by myself? without taking to dealer, or is this something they will have to hook up to STAR.
Quick Question: If it is the fuel pump, does that mean i also have to replace the sending units as well. Ive been searching online for some but have notice that some fuel pump assempbly's come with sending unit and others does not.
Last edited by amgrobaspach; Feb 14, 2018 at 03:01 PM.
Trending Topics




Once you know it is fuel you can work on fuse, relay or pump diagnostics. Keep asking questions so we can help.
Easy way to know if it is CPS - is to replace it with a known good Bosch part. Then keep a known good spare in the glove box for the next time it fails. Replace every 50K for good luck. My wife had one quit on her, which killed the engine, which freaked her out. I replaced it and all is well. But no way does she want that to happen again.
Don't bother with checking compression, unless you are curious. That is rarely the problem (like 1:100,000).
When the spark plug is out, ground the plug and check for spark. If you see spark, it is almost always NOT the problem.
The Best of Mercedes & AMG
Check you fuel pressure first.
Around 5:00pm my buddy showed up to take a look it and to surprise the car started up but I was holding the throttle down as well. It bugged then started.
I then let the car run for about 5min-10min because I was afraid if I turned it off, that it wouldn’t turn back on.
After about 10min of the car running I drove to a nearly gas station and put 3galons of gas in the car just Incase the fuel gauge needle wasn’t working properly. once I got back home and turned the car off, I then tried to start it up again to see if it would start. To surprise it cranked right up not 1 not 2 not 3 but about 5 Times perfect time wihhout even touching the throttle.
I still don’t know what hell it was and afraid it might happen again.
Last edited by amgrobaspach; Feb 15, 2018 at 09:55 PM.
http://thefabricatorseries.com/build...uel-pump-issue
Basically the W203 has a saddle tank (2 fuel tanks) and one fuel pump. The fuel return from the FPR/filter is used to siphon fuel from the driver's side to the passenger side where the fuel pump is. If the FPR fails the passenger side of the tank will run out of fuel when theres still plenty of fuel on the driver's side. The car has 2 fuel level senders (driver and passenger sides) and what you see on the fuel gauge is an average of the 2. On my car with an icarsoft i980 scanner I can see the individual signals from the passenger side and driver sides. When my fuel pump was failing one of the symptoms (besides loss of power) was that there was more fuel on the driver's side than the passenger side which should NEVER happen if the system is working correctly. If you've determined your fuel pump is healthy (56psi at the rail) the next step is the FPR/filter which is easy to replace with basic tools. If that doesn't do it then the next suspect is a blockage in the cross over pipe between the 2 sides like the article above.
https://www.pelicanparts.com/techart...uel_Filter.htm
Last edited by tjts1; Feb 16, 2018 at 12:56 AM.
Long story short, life up your back seat, take off your driver side fuel tank cover and pull off the larger connector. If your prongs are good keep investigating your fuel system because I do agree with previous viewpoints of your issue being very, very likely related to fuel.
The fix was 2 hours of labor or like 225 bucks which is much better than buying the entire fuel tank/pump assembly which is the only way they sell it.




