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04 C230 / 01 E320
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Discussion Starter #1
I HOPE THIS HELPS SOMEBODY ELSE OUT THERE . I REPLACED THE FUEL PUMP IN MY WIFE'S 04 C230 KOMPRESSOR (MECHANIC TOLD US THE FUEL PUMP WAS TOAST) BUT STILL WAS GETTING NO FUEL TO THE ENGINE WHICH OF COURSE WOULD NOT START . AFTER MESSING WITH IT FOR SOME TIME , I ORDERED THE FUEL SENDING UNIT FROM "PARTS GEEK . COM " (WHO BY THE WAY SHIPPED IT OUT VERY QUICK ). AFTER CHANGING THE SENDING UNIT WHICH COMES WITH THE FUEL LINES ATTATCHED WHICH RUN TO AND FROM THE FUEL PUMP , THE CAR STARTED RIGHT UP . AS IT TURNS OUT , THE FUEL PUMP NOR THE SENDING UNIT WERE BAD . THE FUEL LINE THAT RUNS FROM THE PUMP TO THE SENDING UNIT HAD BLOWN UP LIKE A BUBBLE GUM BUBBLE AND BLOWN WIDE OPEN . THE PUMP WAS JUST PUMPING FUEL RIGHT BACK INTO THE FUEL TANK. INSTEAD OF SPENDING $600 ON PARTS I PROBABLY COULD HAVE BOUGHT A $12 FUEL LINE SPLICE KIT AND BEEN DONE. ONLY PROBLEM IS YOU CAN'T SEE THAT PART OF THE FUEL LINE WITHOUT REMOVING THE FUEL SENDING UNIT . AND THESE ARE VERY FRAGILE AND EASY TO BREAK WHEN REMOVING THE FUEL LINES.
 

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2004 CLK 240 Coupe
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11,377 Posts
THE FUEL LINE THAT RUNS FROM THE PUMP TO THE SENDING UNIT HAD BLOWN UP LIKE A BUBBLE GUM BUBBLE AND BLOWN WIDE OPEN . THE PUMP WAS JUST PUMPING FUEL RIGHT BACK INTO THE FUEL TANK.
Interesting - but can you clarify? :confused:...

When you refer to Sending Unit, do you mean the Fuel Level Sending unit? There are 2, one in the left tank side (B4/1) and one in the right tank side (B4/2). These are just floats with electrical outputs to the SAM for fuel level indication. They do not not need fuel lines from the pump.

As I understand it, on your C230 the fuel pump is inside the fuel tank. Can you confirm that your fractured fuel line was inside there?
 

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04 C230 / 01 E320
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Discussion Starter #4
FUEL PUMP / SENDING UNIT

YES , IT'S THE FUEL SENDING UNIT THAT IS BEHIND THE DRIVER'S SEAT . IF YOU BUY ONE OF THESE , THE FUEL LINES THAT RUN FROM THE FUEL PUMP TO THE FUEL SENDING UNIT COME ATTATCHED TO THIS $240 PIECE OF CRAP. ALL THE WIRES THAT CONTROL THE FUEL PUMP ALSO RUN THROUGH THE FUEL SENDING UNIT AND THEN OVER TO THE PUMP . THE PUMP IS EASY, TOOK ME 15 MINUTES TOPS TO PEPLACE . THE FUEL SENDING UNIT IS MORE OF A PAIN IN THE &%#$! THIS THING LOOKS LIKE SOMETHING YOU'D EXPECT TO FIND IN A YUGO OR GEO METRO . WHAT'S HAPPENED TO MERCEDES ?!
 

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2010 C200 CGI /W203/SLK230/W202/230E/280SE
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Hey Scott, that upper case is also a PITA to read!!

Oberoi
 

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04 C230 / 01 E320
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Discussion Starter #6
YES , IT MAY BE . I'VE BEEN AN IRONWORKER FOR 33 YEARS AND MY HANDS AND FINGERS DON'T WORK WELL ON A KEYBOARD SO TYPING IN ALL CAPITALS IS EASIER FOR ME. PRAY MR. ARTHRITIS DOESN'T CATCH UP WITH YOU OR YOU'LL BE TYPING THE SAME WAY.


KEYHOLE , TO CLARIFY A BIT- YES THE FUEL LINES ARE INSIDE THE FUEL TANK AND BOTH LINES RUNNING TO AND FROM THE PUMP , PASS THROUGH THE FUEL SENDING UNIT . YOU CAN'T SEE THEM THOUGH WITHOUT PULLING THE PUMP AND THE SENDING UNIT OUT . AND YES THERE IS A FUEL LEVEL SENDER ON THE PUMP AND SENDING UNIT BOTH . THE FUEL SENDING UNIT AS THEY CALL IT DOES MORE THAN JUST SEND A SIGNAL TO THE FUEL GAUGE . IT CONTROLS THE FUEL PUMP YOU COULD SAY .
 

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2004 CLK 240 Coupe
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KEYHOLE , TO CLARIFY A BIT- YES THE FUEL LINES ARE INSIDE THE FUEL TANK AND BOTH LINES RUNNING TO AND FROM THE PUMP , PASS THROUGH THE FUEL SENDING UNIT . YOU CAN'T SEE THEM THOUGH WITHOUT PULLING THE PUMP AND THE SENDING UNIT OUT . AND YES THERE IS A FUEL LEVEL SENDER ON THE PUMP AND SENDING UNIT BOTH . THE FUEL SENDING UNIT AS THEY CALL IT DOES MORE THAN JUST SEND A SIGNAL TO THE FUEL GAUGE . IT CONTROLS THE FUEL PUMP YOU COULD SAY .
Scott. I'm not trying to flog the issue to death here - but my W209 has the same fuel system design as your W203, so I'm interested in your hands-on experience.

I have attached a WIS drawing below, showing the components inside the fuel tank. I can identify the pump and the level sensors. But I cannot find the 'fuel sending unit' that you refer to. Can you clarify further please?
 

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04 C230 / 01 E320
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Discussion Starter #8
KEYHOLE, YEP THAT LOOKS LIKE THE SAME SETUP . IN THE PICTURE ON THE BOTTOM (THE ONE WITH THE CAR ) THE PUMP IS ON THE LEFT . THE TWO FUEL LINES ARE RUNNING OVER TO THE FUEL SENDING UNIT ON THE RIGHT . THAT'S THE PART THAT'S UNDER THE DRIVERS SIDE BACK SEAT. THAT ENTIRE PART IS THE FUEL SENDING UNIT . THE FUEL LEVEL SENSOR IS JUST ATTATCHED TO IT . THE FUEL SUPPLY LINES AS WELL AS THE ELECTRICAL CONNECTIONS ALL RUN THROUGH THE FUEL SENDING UNIT . THERE ARE FOUR ELECTRICAL CONNECTIONS ON THE FUEL SENDING UNIT BUT ONLY ONE ON THE FUEL PUMP. ONE OF THE FOUR CONNECTIONS ON THE SENDING UNIT RUNS (ALONG WITH THE FUEL LINES ) OVER TO THE FUEL PUMP. THE PUMP , SENDING UNIT , FUEL LINES AND WIRING ALL RUN FROM ONE SIDE TO THE OTHER INSIDE THE FUEL TANK. LOOK UP "PARTSGEEK.COM" AND PUNCH UP 2004 C230 FUEL SENDING UNIT AND THEY HAVE A GREAT PICTURE OF THIS THING WHERE YOU CAN SEE THE OFFENDING FUEL LINES . AMAZING HOW CHEAP THESE THINGS ARE MADE. JUST PLASTIC. I REPLACED THE WHOLE SYSTEM AND SHE'S RUNNIN GREAT . ALL BOSCH PARTS BY THE WAY .
 

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I have a 2005 c230 kompressor sedan. Was running fine, thought I would clean the throttle body so I did unplugged the plug to the throttle body plugged back in now it won't start? Have tried over and over and over. Checked all the fused of the whole car and still nothing. There is a humming noise at the throttle body when I turn the key on, like it's getting power? Any ideas?
 

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Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
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Hi, welcome to the forum! You should consider starting a new thread for this issue as it has nothing to do with this almost 5 year old thread on fuel pumps and senders.
 
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