Fuel leak from top of tank while filling...

inthepyramid

New member
Hey, I'm hoping someone can help me out. 07 3500 Sprinter Fedex Van(Diesel). Starting yesterday, while fueling the tank and once its full or getting full, it starts leaking or overflowing from the top of the tank, I'm guessing maybe from the Fuel Sending Unit Seal? I think it continues to slowly leak throughout the day while I'm driving, as I've wiped the bottom of the tank clean only to find it later on still wet/dripping.
If anyone has run into this issue or may have an idea what could be the cause of it I would greatly appreciate it.
Thanks!
 

GEARS

2005 140WB standard roof
It sounds like the vent hose is no longer connected.

This is known to happen if you fill up from the fatty hosed pump like the semi trucks use.

If you use the big pumps it's best to pay attention to how much fuel you need and throttle the pump down during the last few gallons.

You'll find out more about the tank vent hose by doing a search.

:cheers:
 

mean_in_green

>2,000,000m in MB vans
It's easy to drop the tank down onto the floor with a long board and a jack. You'll have a clear view of the top and whatever the problem is should quickly become apparent.

There are quick disconnects in the fuel lines in front of the tank.

You need to remove the black cover plate at the top of the filler neck to reveal the filler neck retaining bolt. Once you've done that (don't drop the bolt into the tank!) you just need to undo the six torx bolts / three straps underneath.

If it's just a quick look you want you can partially drop it just by undoing the filler neck bolt and lowering it just enough to look over the top.

Bear in mind that if you decide you want to remove the tank completely you'll struggle to do it without having the van up on blocks / ramps as the filler neck isn't removeable from the main tank. You only need to raise the tank side six inches or so to create enough space to tip the tank and pull the whole lot out.
 

inthepyramid

New member
Thanks for your help guys. I dropped the tank last night. The plastic retaining nut that keeps the sending unit down was split. I ordered a new nut and sending unit seal, but until it comes in I used plastic cable ties to keep the nut together. Thanks again for the help
 

irsa76

Member
Another common issue is upfitters drilling through the floor into the tank, had to replace a few Ambulance tanks at the dealer because of this.
 

220629

Well-known member
...
I used plastic cable ties to keep the nut together. Thanks again for the help
Cable ties will work.

FWIW. When I've been unable to get similar parts I have taken a file to make a shallow groove(s) around the nut and then wrap tightly into the groove with some wraps of stainless steel braided picture hanging wire available from Home Depot. As long as the wire fits properly I consider that method permanent for DIY rather than dropping the tank again. It's as strong as the original design when tightly locked into the groove and the ss wire won't deteriorate. vic
 
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