C3 Fuel leak (sending unit)
Thread Starter
Instructor
Joined: Jul 2012
Posts: 174
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From: McDonough Georgia
C3 Fuel leak (sending unit)
My car has been smelling funny (like fuel) for the past few months. I never suspected the fuel tank because it was replaced with a new tank back in 98. Today I decided to inspect the spare tire and things got real interesting. I looked up to where the sending unit is located and noticed a dark greasy substance that smelled a lot like fuel. The spare tire was covered with fuel as well. It appears to be coming from the very edge of where the sending unit is located. This is new to me so any advise will be greatly appreciated. I'm not sure if I need another fuel tank or just the sending unit gasket. Thank you!
Le Mans Master
Joined: Jul 2006
Posts: 8,117
Likes: 104
From: charlotte north carolina
there's no way to know what you need until you remove the sending unit. drain what gas you can into suitable containers by cutting the rubber hose (you'll want a new one, anyway). place a large plastic tub under the sending unit and remove it(about a quart of rusty gas-water mixture will spill out). then report back here.
Thread Starter
Instructor
Joined: Jul 2012
Posts: 174
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From: McDonough Georgia
there's no way to know what you need until you remove the sending unit. drain what gas you can into suitable containers by cutting the rubber hose (you'll want a new one, anyway). place a large plastic tub under the sending unit and remove it(about a quart of rusty gas-water mixture will spill out). then report back here.
Thread Starter
Instructor
Joined: Jul 2012
Posts: 174
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From: McDonough Georgia
You might be right. The red area which I suspect is the "O" ring seal feels real gummy. Does anyone know if a special tool is required to remove the sending unit?
Le Mans Master
Joined: Oct 2006
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Technically, yes a special tool is required. BUT- a small brass hammer and a medium size punch works very well.
Looking at your picture, the lock is positioned so the locking lugs need to be rotated counterclockwise. One of the tabs you can tap on is just above and to the right of the sending unit wire. (there are 3 of them). As you tap on it, try and keep the inner ring as centered as you can- makes it much easier to turn.
Disconnect your sending unit (twist and gently pull), and drain the tank as above.
Looking at your picture, the lock is positioned so the locking lugs need to be rotated counterclockwise. One of the tabs you can tap on is just above and to the right of the sending unit wire. (there are 3 of them). As you tap on it, try and keep the inner ring as centered as you can- makes it much easier to turn.
Disconnect your sending unit (twist and gently pull), and drain the tank as above.
Thread Starter
Instructor
Joined: Jul 2012
Posts: 174
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From: McDonough Georgia
OK, here's what I discovered:
The main pipe that feeds the fuel had a weakened solder joint (see picture). In an effort to save a few bucks, I cleaned the area with sand paper and re-soldered it using silver solder. I reinstalled the unit and I am leak free. A new strainer and gasket was installed as well. I'm not sure if my repair will last or even if soldering it with silver solder is appropriate, but it's working. Please comment if you think my repair won't last and if a better solution might be to just order a new sending unit. Thanks!
The main pipe that feeds the fuel had a weakened solder joint (see picture). In an effort to save a few bucks, I cleaned the area with sand paper and re-soldered it using silver solder. I reinstalled the unit and I am leak free. A new strainer and gasket was installed as well. I'm not sure if my repair will last or even if soldering it with silver solder is appropriate, but it's working. Please comment if you think my repair won't last and if a better solution might be to just order a new sending unit. Thanks!
Last edited by ONeill202; Jun 23, 2013 at 05:43 PM.
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Thread Starter
Instructor
Joined: Jul 2012
Posts: 174
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From: McDonough Georgia
Last edited by ONeill202; Jun 23, 2013 at 07:47 PM.
Thread Starter
Instructor
Joined: Jul 2012
Posts: 174
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From: McDonough Georgia
Last edited by ONeill202; Jun 23, 2013 at 09:04 PM.
Melting Slicks
Joined: Aug 2012
Posts: 3,487
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From: Titusville Florida
On my 76 I have to. Well you don't have to drop the tank completely but you do have to take everything else apart as if you were going to take it out then just rotate is 90* towards you then you can pull out the send unit, just had to do that on mine last week.
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Melting Slicks
Joined: May 2009
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2024 C3 of the Year Finalist - Unmodified
I removed the tank to clean and restore, as well as install a new screen on the pickup. My aggressive cleaning apparently weakened the tube's solder joint, because it started leaking after putting everything together and filling with fuel.
After draining the tank again, I decided discretion was the better part of valor and opted to install a new sending unit. For around $120, it was worth it...considering the danger of fuel leaks and the pain in the a** it is to deal with. Hopefully your repair holds...but I was advised by an HVAC expert who regularly solders tubing...including aluminum...not to mess with it.
After draining the tank again, I decided discretion was the better part of valor and opted to install a new sending unit. For around $120, it was worth it...considering the danger of fuel leaks and the pain in the a** it is to deal with. Hopefully your repair holds...but I was advised by an HVAC expert who regularly solders tubing...including aluminum...not to mess with it.
Thread Starter
Instructor
Joined: Jul 2012
Posts: 174
Likes: 6
From: McDonough Georgia
I removed the tank to clean and restore, as well as install a new screen on the pickup. My aggressive cleaning apparently weakened the tube's solder joint, because it started leaking after putting everything together and filling with fuel.
After draining the tank again, I decided discretion was the better part of valor and opted to install a new sending unit. For around $120, it was worth it...considering the danger of fuel leaks and the pain in the a** it is to deal with. Hopefully your repair holds...but I was advised by an HVAC expert who regularly solders tubing...including aluminum...not to mess with it.
After draining the tank again, I decided discretion was the better part of valor and opted to install a new sending unit. For around $120, it was worth it...considering the danger of fuel leaks and the pain in the a** it is to deal with. Hopefully your repair holds...but I was advised by an HVAC expert who regularly solders tubing...including aluminum...not to mess with it.
Interesting -- Thank you! I'll definitely keep an eye on it and if it doesn't hold it's headed to the trash can.
Melting Slicks
Joined: Aug 2012
Posts: 3,487
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From: Titusville Florida