Fuel leak? 1994 K75RT

[dac0811]

Hi, After a 20 mile ride this afternoon, I noticed fuel leaking from the underside of the tank, and down the air box. Any thoughts on what could be causing this? and the best way to diagnose the issue? Should I remove the tank and so forth?

Any insights would be greatly appreciated.

 

[PGlaves]

Yes, you should remove the tank to examine things. There are a couple of typical possibilities. There is a plate with wires running to it. That is power to the fuel pump and wiring to/from the fuel level sending unit. It is sealed with an O ring. Failure us rare but possible.

Corrosion along the bottom seam on the left side of the tank is also possible. This is where any water in the fuel tank will settle when the bike is on the side stand. Look for blistered paint along this seam.

Both possibilities are repairable.

 

[98lee]

David,

Since the leak is coming out on the right side, I would suspect the O-ring on the fuel level sender.

Fuel Level Float Oring - BMW K ; 62 16 1 459 608 / BMW

Fuel Level Float Oring - BMW K ; 62 16 1 459 608 / BMW

www.euromotoelectrics.com

 

[dac0811]

Many thanks for your responses--ordered the Oring, and will let you know the outcome.

 

[dac0811]

Just a follow up note: When I removed the tank, I found the sending unit to be in good working order, and the O ring intact...however found connections, to the right of the sending unit, on the underside of the tank, without hoses (and presumably missing hoses)--are these venting connections? and do they require special hoses, parts, etc? Guessing that whatever gets connected to these ports, the parts should run into the venting funnel?

As always, thank you for your help.

 

[PGlaves]

Those are vent/drain hoses that operate at atmosphere pressure so nothing fancy is required. Fuel resistant hose is nice.

 

[98lee]

Take a picture of the frame just in front of the cross bar that would be under those nipples when the tank is in place.

One of those nipples (the forward one) is the tank vent. Depending on what is at the frame area under that vent, I can tell you what is wrong.

 

[dac0811]

Thanks very much, Lee and Paul; Lee, please see attached additional photos--top-view and side view.

Best,
David

 

[PGlaves]

Lee will tell you that that little plastic thing is a funnel and no hoses need to be connected to the tank there.

 

[GTRider]

Looking at the stain on the frame and the bend in the side of the funnel, I’m wondering if the tank may have installed such that the spigots were outside the funnel and allowing fuel or water to escape the intended drain path?

Best,
DeVern

 

[98lee]

David,

I will also tell you that the “funnel” is officially called the “air accumulator” by BMW and is referred to as “the cup” by many brick riders.

What I see is a very deformed cup.The left side should be straight. What has happened at some point, is, that during tank installation, the nipples were forced to the left of the cup, instead of inside the cup, causing the tank overflow to go on top of your engine instead of inside the cup.

You might be able to straighten it with some heat or buy a new one

16 13 2 307 467​

AIR ACCUMULATOR​

0.03​

1​

$17.33​

Make sure that the cup drain is connected to the hose that exits down by the right peg plate.

 

[dac0811]

Many thanks for everyone's responses, and direction!

All the best,
David