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Moto Board => Tech => Topic started by: GregP on September 12, 2021, 11:02:50 AM



Title: 2001 S4 Fuel Tank Overflow Drip
Post by: GregP on September 12, 2021, 11:02:50 AM
I have been dealing with fueling issues and a fuel leak for the past year with my old girl and just when I thought I got it all sorted, the fuel overflow hose is dripping fuel pretty aggressively. Any suggestions on what I might be looking at or how to address this would be appreciated.

A little context to go with the question. I had the entire fueling system in the tank to the fuel injection system replaced last year and then sprung a leak at the tank hinge. Finally had the hinge welded and she is fuel tight. I reinstalled the tank and the fuel lines and they are all dry at the tank. Filled her up about 2/3 this morning and took it out for a ride to get fuel back in the system. Everything runs as it should but after the ride, the overflow hose is dripping a drop of fuel every 3 seconds. I have never had a drip from the overflow hose before so it is a little concerning.


Title: Re: 2001 S4 Fuel Tank Overflow Drip
Post by: stopintime on September 12, 2021, 12:02:05 PM
Overflow line not tight?


Title: Re: 2001 S4 Fuel Tank Overflow Drip
Post by: ducpainter on September 12, 2021, 01:48:49 PM
I have been dealing with fueling issues and a fuel leak for the past year with my old girl and just when I thought I got it all sorted, the fuel overflow hose is dripping fuel pretty aggressively. Any suggestions on what I might be looking at or how to address this would be appreciated.

A little context to go with the question. I had the entire fueling system in the tank to the fuel injection system replaced last year and then sprung a leak at the tank hinge. Finally had the hinge welded and she is fuel tight. I reinstalled the tank and the fuel lines and they are all dry at the tank. Filled her up about 2/3 this morning and took it out for a ride to get fuel back in the system. Everything runs as it should but after the ride, the overflow hose is dripping a drop of fuel every 3 seconds. I have never had a drip from the overflow hose before so it is a little concerning.

It's dripping from the end of the rubber hose?

Sounds like a perforated steel tube in the tank, or a leak where the overflow hose, from the cap, attaches to the steel tube.


Title: Re: 2001 S4 Fuel Tank Overflow Drip
Post by: GregP on September 12, 2021, 05:30:42 PM
Dripping from the bottom end of the hose where it routes out below the swing arm. Still bone dry at the base of the tank where all hoses attach. 


Title: Re: 2001 S4 Fuel Tank Overflow Drip
Post by: GregP on September 13, 2021, 05:33:28 AM
It's dripping from the end of the rubber hose?

Sounds like a perforated steel tube in the tank, or a leak where the overflow hose, from the cap, attaches to the steel tube.

Is it possible the heat from the hinge welding damaged something inside the tank? Welder used the lower heat technique of welding in an effort to minimize damage to the paint. Tig v. Mig?


Title: Re: 2001 S4 Fuel Tank Overflow Drip
Post by: ducpainter on September 13, 2021, 02:05:37 PM
Is it possible the heat from the hinge welding damaged something inside the tank? Welder used the lower heat technique of welding in an effort to minimize damage to the paint. Tig v. Mig?
Not likely. Pull the cap, and check the hose connections to the steel tubes, and the cap bung.


Title: Re: 2001 S4 Fuel Tank Overflow Drip
Post by: GregP on September 13, 2021, 05:35:00 PM
Not likely. Pull the cap, and check the hose connections to the steel tubes, and the cap bung.

Thanks. I’ll pull it apart this weekend. In the interim, it appears to have stopped dripping with about 2 cups of fuel having dripped out of a 2/3rds full tank. Is it possible there is a point that it won’t drip below a certain fill line?

I put a mark on the bottle to make sure it hasn’t moved when I check it tomorrow. (Just checked it and the drip has stopped.)


Title: Re: 2001 S4 Fuel Tank Overflow Drip
Post by: ducpainter on September 14, 2021, 04:02:19 PM
Thanks. I’ll pull it apart this weekend. In the interim, it appears to have stopped dripping with about 2 cups of fuel having dripped out of a 2/3rds full tank. Is it possible there is a point that it won’t drip below a certain fill line?

I put a mark on the bottle to make sure it hasn’t moved when I check it tomorrow. (Just checked it and the drip has stopped.)
Yes, the tube connections are close to the top of the tank. I'll bet one of the rubber hoses is split.


Title: Re: 2001 S4 Fuel Tank Overflow Drip
Post by: GregP on September 16, 2021, 06:29:17 AM
Yes, the tube connections are close to the top of the tank. I'll bet one of the rubber hoses is split.

Thanks again for the support.

Unfortunately, the drip has started again, albeit much slower.  The bike has not been moved or even disturbed, so I am a bit confused why it stopped and started again. ???

Time for a long ride to drain most of the fuel and a dive into the tank this weekend.


Title: Re: 2001 S4 Fuel Tank Overflow Drip
Post by: ducpainter on September 16, 2021, 01:47:34 PM
Thanks again for the support.

Unfortunately, the drip has started again, albeit much slower.  The bike has not been moved or even disturbed, so I am a bit confused why it stopped and started again. ???

Time for a long ride to drain most of the fuel and a dive into the tank this weekend.
Temperature shift up?

Split lengthened on a hose with a dip downward into the fuel level?


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