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I would like to thank the other people on the threads about fuel pump. I just installed a new fuel pump and fuel filter. My slk350 was working fine and pulled out of my driveway. About three houses down the car just died. I tried to start the car and it wouldn't. After about 3-4 tries it started and idled rough and died again. Put the car in neutral and pushed it back into the driveway. Hooked up my laptop to see if there was any codes. There wasn't anything showing and could read the car's information. I read how to access the rear fuse box and turned the key to position 2 to see if the relay for the pump was working. That checked out ok. Searched and the fuel pump seemed like the only reasonable issue. The motor would crank, but not start.

Ordered a new fuel pump and fuel filter since I was in there. Read through a DIY and began. Let me tell you...there is a ton of screws you have to take out. I ordered a reverse torx set on amazon and a siphon. Had to siphon out about 7 gallons to not be putting my hands in gas. If your tank is full take out gad from the filler if possible. There is two plastic clips on either side of the pump that you rotate to release. The hardest part was unplugging the cable that went to the sending unit. Plugging the new one was even harder. I ended up releasing the one corner to allow me to pull up the black box in the fuel tank that holds the fuel pump. It was still a pain, but eventually got it. The rest was easy and did reverse.

NOTES:
1. Unplug the battery - I took off the negative terminal
2. Wear clean rubber gloves - mine got cut so still got gas on my hands
3. If you have more than 1/2 tank - try and siphon out gas first before you open/take out the fuel filter - no idea if possible or not
4. Goes without saying, but no sparks/cigarettes obviously
5. I had a fire extinguisher just in case
6. If your in a garage open the door - you will have gas fumes once you take out the fuel filter (did mine outside)
7. Take your time - there is tons of screws
8. If possible break it up into two days - I took everything off first before pump got delivered. Once pump arrived I only had to take out fuel filter and release old pump. Put in new pump/filter and reassemble.
9. Wear a back brace if you have one - mine is killing me bending over for a few hours (Getting old)
10. Others mentioned taking off the fuel line on the drivers side engine compartment - braided line to release pressure (I didn't since I ran my lines dry)

Hope this helps - just wanted to give back since other threads helped me!! On a DIY scale its really not hard. If you are handy with a wrench and have common sense you should be fine (2-3 hrs). If not take it to a mechanic since your dealing with gasoline.
 

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Administrator 2009 SLK 55 AMG/Founding Member 2006
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Hello all. So I read both Fuel Filter and Fuel pump replacement. I can clearly see were the Fuel filter is in the pictures. Question I have is WHERE is the pump located???? Is it in the same hole, in the tank, underneath the fuel filter? How is the fuel pump mounted? What stops it from bouncing around in the tank?
 

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Fuel pump/filter

Hello all. So I read both Fuel Filter and Fuel pump replacement. I can clearly see were the Fuel filter is in the pictures. Question I have is WHERE is the pump located???? Is it in the same hole, in the tank, underneath the fuel filter? How is the fuel pump mounted? What stops it from bouncing around in the tank?
For anybody else that is confused by this, the round unit that is withdrawn from the back of the car contains both the filter and the pump. Hope this helps. :tu:
 

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Premium Member 2005 SLK55 AMG; 2005 SLK350
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Actually, the pump is inside the tank, not part of the filter. You do have to remove the filter to access the pump though.
 

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Actually, the pump is inside the tank, not part of the filter. You do have to remove the filter to access the pump though.
Hi Efair

Thanks for your reply. Are you sure? because this is the part that Mercedes have sold me, although even they seemed a bit unsure. I know that the sender unit is in the tank but haven't really looked that hard until I got this new part. Isn't the fuel pump the bit I have highlighted with an arrow? Help gratefully received.
 

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Premium Member 2005 SLK55 AMG; 2005 SLK350
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That's the fuel pressure regulator, not the fuel pump. I have seen these fail before, causing both over- and under-pressure at the fuel rail, which then causes all manner of strangeness. In our cars at least, the fuel pressure is not monitored via any sensor, so you have to rely on secondary indications, e.g. lean or rich mixture indications, injector timing at limits, etc.
 

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Thanks Efair
So where in the tank is the pump? Mercedes sent me a diagram but even they couldn't identify the pump for me?
My problem is that the car wouldn't start. After replacing the camshaft position magnets and clearing the codes, eventually the reader indicated fuel pump failure. No fuel at the rail .Checked the relay which was ok, testing across the terminals indicated a dead short. Would this be due to the regulator? I hope so as this is driving me mad. :) I suppose all I can do is change this part now I've got it and see if that cures the problem. Would still like to know where the pump is though if you could enlighten me.
Thanks for your help.
 

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Premium Member 2005 SLK55 AMG; 2005 SLK350
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Replacing the filter and regulator is a scheduled maintenance, so no worries with replacing it, especially if it's over-due. It won't help with a shorted motor though. The pump is #20 , and fits down into the hole in the un-numbered assembly right below it in the diagram. After draining your tank and removing your filter, 1) you have to remove the sender, 2)disconnect the pump electrical connector at the bottom, 3) twist the two knobs out of the way 4) lift the pump up and out.

There are tie-straps you may need to slacken or cut; be sure to replace them if so.

I've swapped the filter, but never replaced the pump; I'm just quoting the SSM.
 

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Ok .... the ongoing saga of an SLK fuel pump, so I'm managed to release the fuel pump from the tank. This is done by moving the spring loaded catches as shown in my pictures. The pump housing then comes out by pulling up. You will need to disconnect the filter assembly and push the pipes inside the tank to allow the pump body to come through the hole. Hope this helps some other poor blighter :)
 

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Next problem is Does anybody know the way to take the plastic pump housing apart?
I've got some dodgy photo's of the screwhead but I've never seen anything like it, Torx, Phillips and Straight screwdrivers don't work. Do I need a special tool? anybody give me a clue? TIA
 

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Super Moderator UK SLK 55 AMG 2007
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Next problem is Does anybody know the way to take the plastic pump housing apart?
I've got some dodgy photo's of the screwhead but I've never seen anything like it, Torx, Phillips and Straight screwdrivers don't work. Do I need a special tool? anybody give me a clue? TIA

Hmm!


Might be a special tool.
I'll have a look on the system but I struggle looking for special tools.


If any other mods/minions happen by please have a look.
 

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Super Moderator UK SLK 55 AMG 2007
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I can't find anything that looks useful.


We have a new member who is ex service dept.


I'll tag him and see if he can help. He's UK too.

@Topaz


I've pm'd him too.
He looks to be online regularly.
 

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Oh Thank you so much Avel Du
I've still got a day or so before the new pump arrives, it may already be in the housing I don't know yet, so I'm loathe to start hack sawing through this housing if there is a solution.
Any help you can give me is truly appreciated and hopefully it may help some other member at some time in the future.

Thanks again
Dazz
 

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Registered 2005 SLK55 AMG
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I would wait and see what part you get before you do anything else, although it's been a while I don't remember having take the fuel pump assy apart when replacing pumps in the past. It's normally a straight swap over.. I could be wrong however.

Also how did you test for a short?

From the pictures I can't make out at all what the head is to be honest! Can you get better shots with more light? At a guess they look like an security bit called 'snake eye' - they come in various different sizes. I can't ever remember them ever being used on Merc's but you will be able to see from the picture on the link below as to whether it will fit the screw head better than I can from that picture. They could also be one way shear bolts that use a flat heads, but taper on one side and 'tighten only' they will need drilling out. Both complete guesses until we can get a better photo. Again though, I would wait and see what part arrives before going any further.

https://www.securitysafetyproducts.co.uk/security/security-screws-fixings/snake-eye-security-screw-driver-insert-th5.php
 

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Greetings, First off a big shout out to all the guys that have helped me on this one.
Efair, Avel Du and Topaz. Ok last up I was struggling to get the plastic pump housing apart.
Mercedes wanted £350 for the pump, I should imagine that it would come with all of the necessary parts ready assembled in the plastic housing I was talking about with all of the pipes and wires etc. As I am a cheapskate I thought it was a bit excessive so I managed to source a pump online for £50 (brand new). £300 for some plastic , wire and tubes...... Really Mercedes?
So the plastic housing , in the end I just had a temper tantrum with it and gave it a pull, lo and behold it came apart, no screws nothing just 4 lugs holding it together .... winner :)
So what I had to do is take the 2 rings off the old pump and fit them gently (don't hammer it) to the new pump, these along with the rubber type restrainers are what hold the pump loosely in the plastic housing, I did struggle attaching the main pipe to the pump and it would probably be better to get a really small jubilee clip instead of trying to force the existing clip on.
And that was it, put her back together and she's running like a dream :)
The pump I bought was made by the same company that made the original VDO
Moral of the tale is .... shop around, struggle a bit and use this forum and the great people on here.
 

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Registered 2006 SLK55 AMG
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Help with stuck connector on fuel pump

Well I am at this place too and could use some help understanding how the hose connector to the pump works. I have the ears of the connector pried outwards (pictured), but after some serious pulling in that enclosed space it hasn't even budged! How hard to I need to pull? Am I missing how the connector locks to the flange on the pump?

Thanks up front for any help!

tn

Greetings, First off a big shout out to all the guys that have helped me on this one.
Efair, Avel Du and Topaz. Ok last up I was struggling to get the plastic pump housing apart.
Mercedes wanted £350 for the pump, I should imagine that it would come with all of the necessary parts ready assembled in the plastic housing I was talking about with all of the pipes and wires etc. As I am a cheapskate I thought it was a bit excessive so I managed to source a pump online for £50 (brand new). £300 for some plastic , wire and tubes...... Really Mercedes?
So the plastic housing , in the end I just had a temper tantrum with it and gave it a pull, lo and behold it came apart, no screws nothing just 4 lugs holding it together .... winner :)
So what I had to do is take the 2 rings off the old pump and fit them gently (don't hammer it) to the new pump, these along with the rubber type restrainers are what hold the pump loosely in the plastic housing, I did struggle attaching the main pipe to the pump and it would probably be better to get a really small jubilee clip instead of trying to force the existing clip on.
And that was it, put her back together and she's running like a dream :)
The pump I bought was made by the same company that made the original VDO
Moral of the tale is .... shop around, struggle a bit and use this forum and the great people on here.
 

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Hi Gents,

Could someone confirm the P/N for FUEL PUMP in a SLK55 R171 2009?
I believe it is the same as the 350 discussed here, but cannot be 100% sure.

Thanks !
Fred
 
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