Gasoline leaking on the floor

Tiny
VIVEKHB
  • MEMBER
  • 2003 MERCEDES BENZ C230
  • 1.8L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 230,000 MILES
Leaking fuel lines on top of the gas tank when the car key is in 2nd position or when I crank the engine.

How to replace the sender fuel ports on top of the fuel tank?
How to lower the fuel tank?

Your expert opinion will be highly appreciated.
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Saturday, April 24th, 2021 AT 6:28 AM

16 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

You are lucky on this one. The fuel tank doesn't need to be removed, There is an access port under the right rear seat that can be removed to access the top of the fuel pump and module assembly.

If you look at the pics below, it explains how to remove and replace the fuel pump assembly. If you look at pic 1, it shows the location of the access port. The remaining pics explain how to access it.

Let me know if this helps or if you have other questions.

Take care,

Joe

See pics below.
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Saturday, April 24th, 2021 AT 10:28 PM
Tiny
VIVEKHB
  • MEMBER
Good morning Joe, thanks for your reply, but my car fuel pump is running fine, I can drive the car. But the fuel leaks along the left side of the tank (sending fuel hoses) on the floor as I drive. I tried to confirm with a torch light but I could not confirm as I have to lower the tank partially to have access to the lines coming from the sending unit.
Please, your help will be highly appreciated.
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Sunday, April 25th, 2021 AT 6:04 AM
Tiny
STEVE W.
  • EXPERT
What Joe meant is that to repair it you need to access it and likely replace the assembly if that is what is leaking. This is because Mercedes used a split system with the pump on one side of the tank and the level sending unit on the other, but they are connected by hoses inside the tank. So in order to repair either one you usually need to access both due to the wiring and hoses. If the leak is on the upper side of the tank you should be able to see it through the access ports under the seat. That way you can determine if it's leaking at one of the fittings or if a line cracked or what the issue is. Your description sounds like a failed o-ring in one of the fittings and those are accessible through the back seat ports.
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Sunday, April 25th, 2021 AT 9:40 AM
Tiny
VIVEKHB
  • MEMBER
Thanks a lot Steve. I will proceed as you said and let you know the outcome. Thank you once again.
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Sunday, April 25th, 2021 AT 3:12 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Yep, Steve is correct. That is where I would suspect the leak to be. If you need to, however, I attached the directions for removing the fuel tank. I hope that isn't the case.

If you look at the pics below, they are the directions for removal and install of the fuel tank specific to this vehicle.

I hope this helps. Let us know how things turn out for you.

Take care,

Joe

See pics below.
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Sunday, April 25th, 2021 AT 7:03 PM
Tiny
VIVEKHB
  • MEMBER
Thanks a lot Joe. Hope I don't have to lower the gas tank. But I am very grateful for the detailed diagram. I will do the necessary and let you know as soon as the job is done. Thanks once again.
Vivek
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Monday, April 26th, 2021 AT 2:59 AM
Tiny
VIVEKHB
  • MEMBER
Hi Joe, good evening. I checked both the access ports under the seats and they were dry (no leaks at all). So I think it is the metal line on top of the tank that is rusted? Leaking.I removed the right rear wheel but which fuel tube should I cut, for in the diagram it says fixed fuel lines (9) to cut.I have removed the clip on that hose for your opinion.
I am sending you the actual picture of the car. The other picture of the gas tank (from the internet) which shows the steel line. So if that is rusted and leaking how should I replace it for it seems it is connected to the gas tank and the other end to the fuel filter. Can I replace it with rubber hose? What is the steel line for?Tomorrow I will partially lower the gas tank so I can have access to the steel line.
Your help will be highly appreciated. Thanks in advance.
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Monday, April 26th, 2021 AT 7:04 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

Rubber hoses at the top run to steel. They could be leaking there as well.

The reason that the steel line is used is for safety. It won't melt through like rubber and is stronger and less likely to be damaged if something from the road hits it.

Can you use rubber? You could. Just make sure it is a high-pressure fuel line. They also make special band clamps for high-pressure connections.

IF you are unable to see the leak via the ports, then I honestly recommend removing the tank. If you lower it slightly, you may see the leak but may not be able to repair it.

Also, I made a copy of your first picture and circled a component. I'm having trouble orienting myself. If you look at pic 2, can you identify which part I circled? I don't like the looks of that. It looks like either a tracking arm or a control arm. Make sure the rust isn't
to a point it's weak.

Let me know what I can do to help.

Joe
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Monday, April 26th, 2021 AT 7:37 PM
Tiny
VIVEKHB
  • MEMBER
I got you Joe. I will look at the car and confirm what that component is that you have circled.I wanted you to comment on the thin metal fuel line on the gas tank, I am sure it is that line that is rusted and?Leaking.
Please your expert comments on that.
Secondly, which fuel hose to cut, both or only the one that has the filler tubing attached?
Please let me know. Thanks in advance.
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Monday, April 26th, 2021 AT 8:56 PM
Tiny
STEVE W.
  • EXPERT
It looks like you are missing one clamp and someone changed the filler neck rubber line already. In this image the yellow circles a missing clamp and a replaced clamp on the filler. The xe'd purple lines should be plastic if I recall so those shouldn't be leaking unless they were cracked. The largest is the filler line, the next largest should be the vent tube and the smaller one to the right is the vacuum line from the EVAP testing.
I would drop the tank and look at the lines before you cut anything. The small line in your internet image that runs from the filter over the tank is the pressure fuel line that runs to the fuel rail. It is D in the image I added, If you want to run the line the factory way you would drop the tank and replace the line all the way to the front of the car. If the line is only rusted over the tank you could reroute it around the tank but only if you can get to the line in front of the tank. You would remove the clamp from the line where it connects to the hose on the fuel filter, then find that line in front of the tank. How you repair it depends on what material you want to use, For steel you could find the front line and cut it in a spot in front of the tank, then run a new steel line from there back to the fuel filter connection, You could likely snake it up over the tank and form it in place, it wouldn't be locked into the tank but as long as you secure it there shouldn't be a problem. The hard part will be connecting the new line to the original. As long as they are the same size and very clean you could use a compression fitting to join them. The system doesn't run at extreme pressure so that would work. However you will want to verify that is okay in your area first.
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Monday, April 26th, 2021 AT 11:47 PM
Tiny
VIVEKHB
  • MEMBER
Hi Steve/Joe good morning, I was able to lower the gas tank just enough to confirm that the fuel line was leaking. I used a compression fitting but I could not pass over the gas tank so I manipulated by passing below the tank. I am not happy with the job but I at the end of the day I saved tons of dollars.
Thank you very much for your valuable support. I thank your team for their valuable support. Stay blessed, bye.
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Thursday, April 29th, 2021 AT 6:50 AM
Tiny
STEVE W.
  • EXPERT
Great to hear you got it repaired enough it isn't leaking. Now that you know the way the line ran and where it is you could do a nicer repair in the future if you wished. Or you could be like most of us and do that "temporary repair" that lasts until the vehicle meets the crusher in 10 years. LOL
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Thursday, April 29th, 2021 AT 11:57 AM
Tiny
VIVEKHB
  • MEMBER
Yes Steve, I definitely will improve next time I do have a leak problem. Thanks once again for your expert opinion. Have a blessed weekend, bye.
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Thursday, April 29th, 2021 AT 3:18 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Great to hear you got it fixed. Please feel free to come back anytime in the future if you have questions or need help.

Take care,

Joe
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Thursday, April 29th, 2021 AT 8:53 PM
Tiny
VIVEKHB
  • MEMBER
Good morning Joe, thank you once again for your valuable support. Surely will be in touch for any help as I like to work on my car, it saves tons of money. Have a blessed weekend.
Vivek
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Friday, April 30th, 2021 AT 5:40 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
You are very welcome. I hope to see you in the future.

Take care,

Joe
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Friday, April 30th, 2021 AT 7:16 PM

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