OK I confess to tank pipe confusion !!!

[johnnyalpha]

BMW K75S 1987 approx 70K on clock. New to me from a famous online auction site.

I have been having water in the tank/fuel problems.Got a new rubber tank gasket under the bottom of the cap.
Drain holes line up at 9 oclock position.

I thought it was a bad petrol station experience, but had a lot of water in my petrol recently.
Drained tank, new fuel filter and fresh petrol.
However, I find that I continue to get water into the tank/petrol , not nice situation.

So, fuel tank,petrol pump,filter and out of the tank to the pressure regulator and hence to injectors, I think I get that :)

BUT I am wondering if there is a pipe I have missing from inside the tank.
For instance where does the water or overfill go to after the drain hole by the filler cap ?

Please pity my state of ignorance, any information for my sad state of un enlightenment very much appreciated Best Wishes Johnnyalpha Scotland (where it rains,a lot )

[Laitch]

For instance where does the water or overfill go to after the drain hole by the filler cap ?

I think you might consider removing the cap assembly, draining the fuel, then checking the fuel cap drainpipe for integrity. It exits from the underside right rear of the tank—behind a tank vent pipe—and is attached to a hose that ends behind the right footpeg plate, or the pipe drains directlyinto a cup attached to the frame under the tank.

The attached photo is showing the rear interior of the tank. The drainpipe attachment point at nine o'clock is not quite visible at the right.

If that pipe is ok then wailing, moaning and gnashing of teeth—along with further consultation—will ensue.

[Scott_]

It has not been unheard of for the key lock assy to leak water into the tank..........

[Laitch]

It has not been unheard of for the key lock assy to leak water into the tank..........

So if the pipe is ok, following on from Scott_'s observation there's this.

[jaxon]

So if the pipe is ok, following on from Scott_'s observation there's this.

Heads up! That spring will get away from you. Completely empty your garage before taking that cap apart. It'll be easier to find later.

[bmwpyro]

Johnnyalpha, can you add a picture of your tank internals?

[johnnyalpha]

Thanks for the replies. I shall have to check all this out, unfortunately, using bus to commute,it shall be the weekend before I can. Still getting dark early here (Scotland) at this time of year. I don't have a garage and the bike lives outside,now covered with a stout waterproof cover for the moment.

So this plumbing is "solid" not rubber,mmmhhh

I take it that blocking the drain hole from the cap won't help ?

I shall investigate further, but now wondering if my plumbing is complete or maybe damaged somehow,painful !!!

BW Johnnyalpha

[Laitch]

I shall investigate further, but now wondering if my plumbing is complete or maybe damaged somehow,painful !!!

All will be revealed in the fullness of time.  :oldguy:

[milq]

Slight detour...is the cap actually vented or does the tank vent elsewhere?

[johnnyalpha]

Thanks for all the replies, pity I can't do much until the weekend.

shall update when I can

VBW J

[johnnyalpha]

OK, I got a hour or so of daylight, so I had a look at the tank.
Firstly I thought that a PO had deliberately blocked the hole with epoxy or something,I just could not get anything down
there. So I took a small nail and tapped it in very gingerly,it wasn't that hard,but it was gritty and crusty,then I had BREAKTHROUGH.
It all fell away and the hole was clear. Next step was to take some strimmer spool,and I was able to feed it right through until it popped out the bottom of the tank :)))) I then danced a wee jig. Then cleaned and cleaned with brake cleaner and strimmer plastic.
Then I dropped a small amount of water on the edge of the cap and was gratified to see it head down the drain hole, a wee bit more and it did the same :) 
Then I used silicone grease to seat the tank rubber seal,under it and on top, then re installed the cap.
Quick whiz up and down and the bike ran really well.

I feel reasonably confident that this has solved the water getting into the tank problem,time will tell of course.
This process of keeping the drain clear will now be part of my maintenance routine.

I would like to thank everyone for the input, I am indebted to you all.

BW Johnny Z

[Laitch]

I would like to thank everyone for the input, I am indebted to you all.

Good followthrough, Johnny!
I like shortbread so it would be ok to leave a small tin of it on the front porch when you're in the neighborhood. :giggles

[johnnyalpha]

Righto, nae bother at a' !  :)

[The Mighty Gryphon]

That trimmer line is a brilliant idea.  I have at least one bike I need to do that on now. 

Will be adding to my maintenance list as well.