95 R1100GS Fuel Tank Water in gas cap opening

[Freeman1100GS]

I am a first time owner of a BMW. After I picked up my GS I washed and cleaned it up I went to put gas in it and there was standing water inside the rim of the gas tank opening. My first thoughts that it was the seal between the tank and the bolted housing of the fuel cap assy. Then I started to wonder if it was leaking from around the hinge or or maybe a bad seal on the cap itself when I secure it down.

Any thoughts or advise?

 

[Cook1e]

I'm not certain that the 1100 is the same, but on the 1150 there is a drain-hole under the cap, in the recess round the filler neck. This is the end of a steel pipe which goes through the tank and connects to a rubber drain tube on the right-hand side.

The steel pipe is prone to blocking up with rust and crap. it can be cleared with e.g. a length of scrap bowden cable and a degree of patience...

 

[DrFarkoff]

AS you sit on the bike and look in the fuel tank filler area, If you take the front as twelve o'clock and the rear as 6 o'clock

If there is water still in there? Use a syringe or something to remove it, Pet shops and farm shops oftem have 50 ~60Ml syringes) a sponge or microfibre cloth will also do but try not to let the water get into the fuel tank obviously

Then at 9 o'clock there should be a small hole DON'T POKE anything in there YET!!!! All you will do is compact it into the hole and make it more difficult to remove!!!!

This the filler area drain and is a metal tube wound around the filler neck which then connects to a small rubber hose which exits the fuel tank pump flange (there are two of these smaller pipes exiting the fuel pump flange One is the Fuel tank Breather and the other is the Fuel tank filler drain)

They meet at a plastic straight connector which is on the right side of the bike just behind the black plastic cover

Start there and disconnect the lines and You could try blowing into each pipe The one that you can hear air hissing into the tank is the breather

With the other one will probably be blocked You can try scooting Penetrating oil in the area of the drain hole and leave it a while and blow again

IF you have a compressor with a blow nozzle you can hold it back from the hose and scoosh air at the hose and see if it releases the dirt out "But" Don;t plug it into the hose and blow high pressure air up the pipe!! You will blow the hose off in the tank

Its basically get that dirt out of the hole and once the plug is out you can clean it with a bit or 0.6 mm Mig wire or bowden cable

When you are using penetrating oil You can give an initial squirt of WD40 to loosen stuff in the drain hole BUT don;t spray it liberally down the hole as WD40 degrades rubber I am not sure of its effect on the hose through the tank !!!

Once you have the hole clear you can use some rubber friendly spray to help move stuff out ACF50 is good to treat the rust

And if you have to remove the Fuel pump flange or the filler cap ?? Order the New O Rings before you start !! 100% they will swell once they are exposed to air and then you are screwed if you are in a hurry !!!

 

[oblertone]

... you can also use nylon strimmer line for this most delicate of tasks

 

[Freeman1100GS]

Thank you all for the response and being so thorough. I will do exactly as you say.

 

[wreck diver]

Wise words from Dr F about the o ring ��
I recently did the same job and sure enough the O ring wouldn't re seat!

 

[JohnnyBoxer]

I had to do this again, yesterday.............right PITA

It's a bi-annual job