johnand

So, if you have been following this thread: https://mbworld.org/forums/c-class-w...ard-start.html you can see that my 07 C230 will not start. I replaced a known revised CPS, and still no start. Hooked up a fuel pressure gauge, and I have no pressure. Then, I checked the fuel pump fuse and relay, and they are good. Then, I tried to find the fuel pump under the seat to test it, and then I got a little confused. Here are the pics. This is the passenger side:



This is the drivers side:



So, after some digging around in WIS wiring diagrams, I found the wiring for the pump which is on the passenger side. But, then I am confused with this. Clearly the fuel line is attached on the driver's side, but the fuel pump on the passenger side has no fuel lines? How does that work? Where is the wiring for the 2nd level sending unit? Any help in sorting this out is appreciated. I don't want to tow it to the dealer to fix.

d1no

http://www.installuniversity.com/mb/w203/w203/fp.html

Thats a DIY for fuel pump replacement on 02 c240.. Hopefully not much has changed and those pics help you a bit.

cpbeasley

so the other side is just a fuel level sending unit?

Glyn M Ruck

See my reply PM to yours.

The pump is on the LHS (drivers US) side on 99% of W203's. I have seen one car with it reversed.

Glyn M Ruck

Yep - That is how most cars are. But John has the final W203 with the fuel filter in the tank. From his pics above the pump is still seems to be on the drivers side of his car unless they moved it to make space for the filter. What I don't understand is why the wiring is so heavy to the passenger side which used to be a level sensor only.

I think those plastic covers need to come off to see all the pipe routing.

d1no

Oh ok, So my 2005 c230k has the same setup as the c240 from installuniversity link? I would have to get that tool for the locking ring? So in the 2007s since the fuel filter is in the tank they have to get to the tank to change it out or what?

splinter

If you haven’t already finished…
Almost certain the right hand side is the pump proper; mine was.
Some wires & hoses that connect with the RH pump run in the tank from the level sensor.

On the road as I post this. Will update further this evening if need be. Good luck amigo.

Glyn M Ruck

John - I have trawled through the EPC & your car seems to be a crossover vehicle that looks more like a W204 than a W203 in this regard

The W204 has the fuel pump on the RH (passenger US) side of the car & one of the sensors & other gubbins on the LHS.

Your fuel system is not the same as earlier W203's

Glyn M Ruck

splinter - my car is configured like yours but most on the forum are not (US at least)

Glyn M Ruck

Your car should have the set up like installuniversity. There is one easy way to check which side the pump is mounted. Put your ear to the rear seat & listen for which side has the pump whine. If you can't hear it with the engine running the let the car stand overnight and you might hear it more easily as you switch on to crank. With the seat out you can clearly hear where the pump is. I should also point out that the 4 cylinder engines have a different injection system to the V6 although they share most tank etc parts.

Your car should require the ring tool but the only way to know for certain is to check. Benz changed at some VIN number that I can't find.

Your car should have the external filter next to the tank with the built in pressure regulator. John's car has the filter inside the one tank module.
Your car s/b like this - Ignore the fact that this says M272 engine - John's car has M272 & the filter is in the tank:

https://mbworld.org/forums/attachmen...unction-1-.pdf

This - which side is the fuel pump nonsense of Benz got me into trouble with a member in my early days on the forum. I had presumed incorrectly that all cars were RHS. I also got involved with ChrisBrown's car which has a noisy pump & that was LHS IIRC.

johnand

Thanks for the replies. I am 99% certain the passenger side is the pump side. Those are heavy gauge wires as Glyn pointed out, and the color code matches what the WIS diagrams say is M3 (fuel pump). I realized when I was thinking about it that Splinter is right, and there has to be fuel lines and other wiring running to the other side.

Parts.com has the pump for $173. Going to call the stealer in the morning and see what they want for a pump.

Glyn M Ruck

I think you are correct - do you get 12 volts at the RHS plug?

johnand

10.89V while cranking. Does that sound ok?

Glyn M Ruck

Yes - the pump should be fine with that! As I said in PM the older Pierburg & Bosch pumps had 7 to 15 volt operating latitude.

johnand

I figured as much from what you said. The top of the pump says VDO. Maybe the sending unit?

Glyn M Ruck

No actually - VDO makes fuel pumps & maybe Merc has moved from Bosch & Pierburg to VDO.

I noticed the VDO in your top pic. They obviously make sensors & gauges as well. With bean counters around maybe VDO got the new contract. Imagine they would have to meet the same spec.

I'm old shool. If it has a Bosch injection system I wish they would keep it all Bosch. When I see all the trouble they have had with crap Delphi injectors on the diesel Blue Efficiency range I have to ask - why did they change???

johnand

Agreed.

The drivers side pic shows a Delphi part. Not sure if it is a pressure regulator, sending unit or what? I'll look at the schematic just for curiosity.

So, with all that said, I now am 100% sure the pump is toast. The real question is why it failed so soon? Think the fairly large quantities of E85 that passed through it had anything to do with it?

Glyn, I know you frequent the 204 forum, so any pump failures you can recall? I doubt there is many 204's up to the mileage of my 203, but interesting to see if the 204 start seeing early pump failures.

d1no

Thanks for the reply Glyn. So lets say I do require the ring thing, is there a way to take it out without it because the tool alone cost over 100 bucks. Yes my car has the fuel filter under the car next to the rear driver wheel. I might be having to replace my pump too if it fails soon.

Hey John how'd you get that price on the parts.com website. For me it shows 230$ when I look it up

LILBENZ230

I'm not sure why E85 would cause a fuel pump failure since the car is rated to work with E85. This sucks, though. How many days now has it been a garage decoration?

Glyn M Ruck

You can butcher the rings off with a screwdiver & hammer, piece of wood & hammer, I've seen people expand pullers & rotate them. All methods are tacky but can work. You could even file & weld up a tool if you are good at that.

Glyn M Ruck

Indeed - John's is a Flexfuel car but the pumps run flooded & the E85 might have chewed the insulation off of the armature windings.

Alcohols can do awful things - I know - we had to tolerate Sasol heavy alcohols in our fuel for years & I have plenty of experience in Brazil with their hydrous & anhydrous alcohols.

LILBENZ230

Interesting. It seems Mercedes should have done what was necessary to make sure that didn't happen before saying it was okay to use E85.

Glyn M Ruck

There have been a number of fuel pump failures on the W204 - generally at very low mileage.

Example - https://mbworld.org/forums/c-class-w...ight=fuel+pump

Glyn M Ruck

Yup! they probably did not test far enough. In SA Benz vehicles were quite good on alcohol laced fuel but BMW's had huge trouble - screwed up their injection systems big time in those days. Benz who used many similar parts had, had them plated differently & changed all elastomers to be alcohol proof.

Benz over the years has cheapened many things to keep their cars cost competitive & it shows. I still remember the day Jürgen Schrempp informed the German board that their cars were "over engineered"

LILBENZ230

Ahh.. they should be engineered and then priced, not priced then engineered.. IMO.