06 r class fuel pump replacement.
Junior Member
Joined: Jun 2007
Posts: 41
Likes: 0
From: Vancouver Canada
1991 190E:1998 E320 4Matic wagon : 2000 E320 4Matic
fuel pump replacement 2006 R350 W251
How we removed and replaced a fuel pump on the Mercedes R class 350 W251. First you need to know that the fuel pump is underneath the right side of the car or passenger side (Canada) of the second row of seats. You need first to remove the seat to gain access to the pump
Remove the seat by removing the plastic covers at the back and the front of the seat rail. They cover the four Torx bolts that hold the seat rails to the chassis. I remove the covers by prying the front ones forward and pushing the rear runs backwards, I managed to remove them without breaking them. Once the four bolts have been removed the seat and rails simply lifts out. Slide the seat forward and backward for easy access to bolts. You now need to pull part of the carpet forward to expose the plate that covers the fuel pump access compartment. We cut the carpet to make access easier to the fuel compartment. The plate is not screwed in but a sealant has been used to attach it to the floor. We used a heat gun to heat the sealant and an Exacto knife and screwdriver to pry the cover off. Once the cover is off the fuel pump access is exposed and there is a locking ring holding the fuel pump in place. There is a special fuel pump lock ring removal tool but we didn’t have it and I actually ended up using a Dremel to cut the ring off because we couldn’t get it off with the tools at hand. I wouldn’t recommend this but it worked. Once the ring is removed the fuel pump pops up and is easily removed. There are three or four electrical connectors that need to be removed and approximately three hoses. It is a good idea to look at the new pump before removing the old one as the unit comes comes completely out. Before beginning the job buy your pump and a new lock ring and O-ring seal as well. It’s a good idea at this time to also replace the relay and fuse as they’re not expensive. There is a small fuel line connected to the top of the pump and clamped on , it does not have to be removed... it is part of the new pump. You will need to pinch the bottom of the fuel line that is attached to the top of the pump to remove it. The lock ring removal tool Is Lisle 63000 and sells for approx. $40. I don’t recommend cutting the ring off as we did, you could easily damage the threads on the fuel tank and not be able to reseat the ring
AutohausAZ sell the pump for $315 and the lock ring and seal for $34 USD. AlldataDIY allows 3 hours for this job. I am too embarrassed to say how long it took us to do it but will say that having the right removal tool and knowing where the pump and relay are and how to remove the seat that the job can easily be done in the 3 hour allotment
Remove the seat by removing the plastic covers at the back and the front of the seat rail. They cover the four Torx bolts that hold the seat rails to the chassis. I remove the covers by prying the front ones forward and pushing the rear runs backwards, I managed to remove them without breaking them. Once the four bolts have been removed the seat and rails simply lifts out. Slide the seat forward and backward for easy access to bolts. You now need to pull part of the carpet forward to expose the plate that covers the fuel pump access compartment. We cut the carpet to make access easier to the fuel compartment. The plate is not screwed in but a sealant has been used to attach it to the floor. We used a heat gun to heat the sealant and an Exacto knife and screwdriver to pry the cover off. Once the cover is off the fuel pump access is exposed and there is a locking ring holding the fuel pump in place. There is a special fuel pump lock ring removal tool but we didn’t have it and I actually ended up using a Dremel to cut the ring off because we couldn’t get it off with the tools at hand. I wouldn’t recommend this but it worked. Once the ring is removed the fuel pump pops up and is easily removed. There are three or four electrical connectors that need to be removed and approximately three hoses. It is a good idea to look at the new pump before removing the old one as the unit comes comes completely out. Before beginning the job buy your pump and a new lock ring and O-ring seal as well. It’s a good idea at this time to also replace the relay and fuse as they’re not expensive. There is a small fuel line connected to the top of the pump and clamped on , it does not have to be removed... it is part of the new pump. You will need to pinch the bottom of the fuel line that is attached to the top of the pump to remove it. The lock ring removal tool Is Lisle 63000 and sells for approx. $40. I don’t recommend cutting the ring off as we did, you could easily damage the threads on the fuel tank and not be able to reseat the ring
AutohausAZ sell the pump for $315 and the lock ring and seal for $34 USD. AlldataDIY allows 3 hours for this job. I am too embarrassed to say how long it took us to do it but will say that having the right removal tool and knowing where the pump and relay are and how to remove the seat that the job can easily be done in the 3 hour allotment
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Joined: Sep 2018
Posts: 14,679
Likes: 4,578
From: unbegrenzt
2017 GLE350 4MATIC
For a general idea on how this is done, go to Senior Leigh's channel on YouTube. He repaired a W221 fuel pump seal, and the pump is the next step in the same procedure. He is user @39039 on this site.
Senior Member
Joined: Mar 2017
Posts: 258
Likes: 50
R320, Astro, JSW, ST4
Pump is held down into tank by a lock ring screwed down over the mating flange.
(Pump housing, flange and locking ring are all made of plastic)
It is sealed with a large green o-ring.
When I replaced mine, my mechanic suggested to replace the locking ring and o-ring. Said they usually needed to replace it.
O-ring is sold with the locking ring, part #1644700230 https://newparts.com/product/genuine...enz/1644700230
$37+tax.
I thought to myself right / no way I'm gonna buy this kit it should be reusable. (I never needed to buy this with VW - their o-ring is easily reused)
I was wrong, the MB design is fiddly and does indeed work better with a replacement / fresh locking and o-ring kit.
Be absolutely sure your lift pump needs replacement, through good testing. They don't fail often.
(I guess I might as well take the opportunity to mention I have a good used unit on the shelf for R320 $100 + shipping
Probably fits ML diesel fine.)
(Pump housing, flange and locking ring are all made of plastic)
It is sealed with a large green o-ring.
When I replaced mine, my mechanic suggested to replace the locking ring and o-ring. Said they usually needed to replace it.
O-ring is sold with the locking ring, part #1644700230 https://newparts.com/product/genuine...enz/1644700230
$37+tax.
I thought to myself right / no way I'm gonna buy this kit it should be reusable. (I never needed to buy this with VW - their o-ring is easily reused)
I was wrong, the MB design is fiddly and does indeed work better with a replacement / fresh locking and o-ring kit.
Be absolutely sure your lift pump needs replacement, through good testing. They don't fail often.
(I guess I might as well take the opportunity to mention I have a good used unit on the shelf for R320 $100 + shipping
Probably fits ML diesel fine.)
Last edited by B34chBum; Apr 15, 2021 at 09:46 AM. Reason: correction
Newbie
Joined: Jan 2022
Posts: 4
Likes: 0
R350
How we removed and replaced a fuel pump on the Mercedes R class 350 W251. First you need to know that the fuel pump is underneath the right side of the car or passenger side (Canada) of the second row of seats. You need first to remove the seat to gain access to the pump
Remove the seat by removing the plastic covers at the back and the front of the seat rail. They cover the four Torx bolts that hold the seat rails to the chassis. I remove the covers by prying the front ones forward and pushing the rear runs backwards, I managed to remove them without breaking them. Once the four bolts have been removed the seat and rails simply lifts out. Slide the seat forward and backward for easy access to bolts. You now need to pull part of the carpet forward to expose the plate that covers the fuel pump access compartment. We cut the carpet to make access easier to the fuel compartment. The plate is not screwed in but a sealant has been used to attach it to the floor. We used a heat gun to heat the sealant and an Exacto knife and screwdriver to pry the cover off. Once the cover is off the fuel pump access is exposed and there is a locking ring holding the fuel pump in place. There is a special fuel pump lock ring removal tool but we didn’t have it and I actually ended up using a Dremel to cut the ring off because we couldn’t get it off with the tools at hand. I wouldn’t recommend this but it worked. Once the ring is removed the fuel pump pops up and is easily removed. There are three or four electrical connectors that need to be removed and approximately three hoses. It is a good idea to look at the new pump before removing the old one as the unit comes comes completely out. Before beginning the job buy your pump and a new lock ring and O-ring seal as well. It’s a good idea at this time to also replace the relay and fuse as they’re not expensive. There is a small fuel line connected to the top of the pump and clamped on , it does not have to be removed... it is part of the new pump. You will need to pinch the bottom of the fuel line that is attached to the top of the pump to remove it. The lock ring removal tool Is Lisle 63000 and sells for approx. $40. I don’t recommend cutting the ring off as we did, you could easily damage the threads on the fuel tank and not be able to reseat the ring
AutohausAZ sell the pump for $315 and the lock ring and seal for $34 USD. AlldataDIY allows 3 hours for this job. I am too embarrassed to say how long it took us to do it but will say that having the right removal tool and knowing where the pump and relay are and how to remove the seat that the job can easily be done in the 3 hour allotment
Remove the seat by removing the plastic covers at the back and the front of the seat rail. They cover the four Torx bolts that hold the seat rails to the chassis. I remove the covers by prying the front ones forward and pushing the rear runs backwards, I managed to remove them without breaking them. Once the four bolts have been removed the seat and rails simply lifts out. Slide the seat forward and backward for easy access to bolts. You now need to pull part of the carpet forward to expose the plate that covers the fuel pump access compartment. We cut the carpet to make access easier to the fuel compartment. The plate is not screwed in but a sealant has been used to attach it to the floor. We used a heat gun to heat the sealant and an Exacto knife and screwdriver to pry the cover off. Once the cover is off the fuel pump access is exposed and there is a locking ring holding the fuel pump in place. There is a special fuel pump lock ring removal tool but we didn’t have it and I actually ended up using a Dremel to cut the ring off because we couldn’t get it off with the tools at hand. I wouldn’t recommend this but it worked. Once the ring is removed the fuel pump pops up and is easily removed. There are three or four electrical connectors that need to be removed and approximately three hoses. It is a good idea to look at the new pump before removing the old one as the unit comes comes completely out. Before beginning the job buy your pump and a new lock ring and O-ring seal as well. It’s a good idea at this time to also replace the relay and fuse as they’re not expensive. There is a small fuel line connected to the top of the pump and clamped on , it does not have to be removed... it is part of the new pump. You will need to pinch the bottom of the fuel line that is attached to the top of the pump to remove it. The lock ring removal tool Is Lisle 63000 and sells for approx. $40. I don’t recommend cutting the ring off as we did, you could easily damage the threads on the fuel tank and not be able to reseat the ring
AutohausAZ sell the pump for $315 and the lock ring and seal for $34 USD. AlldataDIY allows 3 hours for this job. I am too embarrassed to say how long it took us to do it but will say that having the right removal tool and knowing where the pump and relay are and how to remove the seat that the job can easily be done in the 3 hour allotment
Last edited by Sweerbaby101017; Jan 24, 2022 at 01:00 AM.
