Gas Leak - 2002 R1100S

[chrisfrank]

I get an intermittent gasoline leak when I first start up the bike to go to work in the morning. It drips down from the area in the picture . Its leaks enough to create a small puddle under the bike within a minute of startup - and has forced me to drive my truck to work four times in the past month. In the picture, I've got the tank propped up with the engine running trying to recreate the leak. Of course, it only leaks when everything is reassembled. All the hoses feel tight. Any ideas?

[Noblehops]

Originally Posted by chrisfrank

I get an intermittent gasoline leak when I first start up the bike to go to work in the morning. It drips down from the area in the picture . Its leaks enough to create a small puddle under the bike within a minute of startup - and has forced me to drive my truck to work four times in the past month. In the picture, I've got the tank propped up with the engine running trying to recreate the leak. Of course, it only leaks when everything is reassembled. All the hoses feel tight. Any ideas?

I went through a thrash with this, and I'll tell you what I explored and what it was.

Where you are pointing there is what I call the equalization hose, which is designed to let the fuel level equalize from one side of the tank to the other. It's held on to the tube with single-use fuel injection clamps. That's a possibility. I suspected my hose and that joint, replaced it all, and it turned out not to be the issue.

Second, you're obviously right below the fuel pump assembly and a giant o-ring joint. I'd be tempted to service the fuel filter and replace that O-ring between the plate and the tank, paying particular attention to getting even pressure on the six screws to the tank. That's my guess as to where the problem is.

Third, you can sometimes detect a small leak with spray powder deodorant. Spray it in the area of the leak, recreate the leaking situation, see if there is a telltale track through the powder.

Finally, you could have a leak in the joint there the aluminum is welded. I had a leak at a weld point in my tank as it turns out, and ended up having to replace my tank, swapping over the filler neck and cap and fuel pump. The good news is that good used tanks go by for somewhere near $100 from time to time.

More about my chronicles here:

http://forums.pelicanparts.com/bmw-r1100s-r1200s-tech-forum/608975-spruce-up-2001-1100s-light-3.html

Good luck!

N.

[JimMoore]

It could be there or it could be at your quick disconnects. On a bike that age I'd start thinking about replacing all the fuel lines and clamps, and replacing the crappy BMW QDs with some trick QDs from beemerboneyard.

If you don't watn to go to all that trouble I might try putting another clamp on all the spots that are clamped now.

[tjs]

maybe an illusion but it looks like your missing 1 of the allen bolts on the plate. i have seen them overtightened to the point the head breaks off. If this is so it is most likely where the leak is. My brother broke one and it leaked a very small amount of gas from that area. 2cnts from tjs

[chrisfrank]

When it leaks, the leak is pretty big - 4 or 5 drops per second. Makes me think it's from a pressurized gas line. A friend with a Suzuki DR650 said his gas tank/pump setup is the same. He said vibration can cause a crack where the metal gas tube goes through the big round plate. He suggests using JB Weld around that area. I've started it up a dozen times since last night and can't get it to leak. I understand one of the gas lines is an outlet from the pump and the other one is a return line to the tank. Is that right? Which one is the high pressure feed line? How does that work anyway? I tried the white powder trick to try and pinpoint the problem. No luck with that. At the very least, I'll double-up on the hose clamps before putting it back together.

[JimMoore]

Originally Posted by chrisfrank

I understand one of the gas lines is an outlet from the pump and the other one is a return line to the tank. Is that right? Which one is the high pressure feed line? How does that work anyway?

The lower line is the feed line. Upper is return. They're both under pressure though, so it could still be either one.

The fuel pump runs all the time. High pressure fuel goes to the fuel pressure regulator, where it is sent to the injectors. Excess fuel comes back to the tank via the return line.

[WillieMcG]

Hi
I know this is a long time later.. Did you find the source of your leak? I have exactly the same problem.

Regards

Willie

[scotland]

I also have a similar leak ('04 R1100S, All Stock). If you could please..what was the final resolution of your leak?

I removed the tank and found nothing obvious, although with my aged 'Cycle' I will be replacing the the fuel lines at a minimum.

Thanks in advance...Kirk

[jkeating]

Dealing with this same issue on my bike. My leak is clearly coming from the area of the tank’s service plate and seems to “fix” itself after the bike runs for a bit, and is used regularly. Only to return if the bike sits a while (more than a few weeks). I removed the tank today and will be using that as an opportunity to service the innards of the tank; hoses, filter, gasket,... i don’t believe my issue is related to the integrity of the tank itself because of the intermittent nature of the problem. I suspect it’s the gasket at the service plate, but I’ll report back after I’ve gotten the tank serviced, and/or fixed the issue. I hope you others will as well.

It’s winter where I am, so don’t expect a super fast repair and report.

[scotland]

This bike had not been ridden or started for a couple of months or so. Took it out for a 'maintenance run' and after a few miles I noted the leak running down one of the pre-formed hoses near the 'plate'. I let it sit and cool down, then set up a cooling fan in the garage and ran it for several minutes @ various rpm's..No Leak. Then just when I was going to shut it down, it again began leaking down one of the pre-formed hoses. When I pulled the tank I could see a lot of age cracking/splits at the hose ends.

My thought is that if it was leaking from the 'plate' to tank O-ring..that it would drip down the tank, rather than down a hose (unless it was a 'bigger' leak that may then transfer fuel over to the hose). So, two hoses at about $60 on order and the process of elimination begins..taking the down time to address a couple other things as well, ie charcoal canister removal, new battery, etc.

Will update this accordingly...Hopefully it will not be a long 'replacement' process of other components.

[BadToTheBown]

When mine happened, new hoses. I made a mistake in trying fuel line from local auto parts store, which were not metric, just close. They leaked to, could get it to stop with extraordinary clamp tightening, right answer proved to be the correct metric lines...replaced them all...good luck...

[square4man]

My 04’S would drip when 1st started after winter nap (months). Drip stopped within a few minutes but because it only leaked while the bike was running and not sitting with a full tank I suspected supply/return hoses. I bit the bullet and replaced hoses, fuel filter and O ring. Those molded hoses are expensive but you don’t want to have to do this often. Got my stuff from BeemerBoneyard and EME. Good luck.

[scotland]

Thanks for the feedback B'toB' and S'4man! Finally got the 2 pre-formed hoses (supply #13537687246..return #13537687245). Installed, ran for a while in-place (w/cooling fan) and then rode for several miles..NO LEAK, although I feel more miles are necessary for full confirmation. I used the BMW reusable hose clamps (#17121461500)..these clamps are larger than the crimp-on type, and if used under the tank, inspect very carefully when tank is re-installed..there is not much room between the fuel lines and other components. I had to rotate/adjust the return line clamp as it was rubbing/touching against the oil-cooler tubing..(which in itself was very difficult to see/ascertain!!).

While the tank was off, I also removed the charcoal canister, following the directions of this and other sites. I since noticed a rougher idle and some intermittent 'popping and coughing'..not sure if the canister removal is a contributing factor, or that it's just time for a throttle body sync (been about 7k to 8k miles)?!..while the valves were recently adjusted.

BTW..I really like the suggestion/method (found on this site) of laying the tank on its side, while supported by the right cylinder head & stabilized w/bungees . It is great for a quick 'look-see' or minor intervention to the area.

[scotland]

Correction..the 'rubbing/touching' of the fuel hose clamp was actually the Feed/Supply line.

[BadToTheBown]

double check for a vacuum leak with the hoses...just a guess...

[punkassjim]

Just to chime in that I had a similar leak, and it turned out to be brittle/cracking fuel line at the pump connections. Replaced the supply and return line with fresh BMW hose, and the fire hazard is gone.

[flatbutt]

Similar leak on mine and replaced all lines because I'm a replace over repair kinda guy.

[Niceboxer]

did you find/fix the leak yet? My tank was leaking at the inside weld of the bracket which holds the tank up on the frame, took me a while to finally find it. I was able to patch it temporarily with tank repair compound, but eventually replaced the tank. In my case, the weld probably failed when the bike was laid down at one point

[jkeating]

Finally got around to fixing this. I originally thought my leak was coming from the o-ring that seals the tank connection/access panel. Nope. It was one or both of the high pressure fuel lines. They were hard and brittle after 20 years. Since the tank was off the bike I replaced the fuel filter and all external lines. So far, so good.

[kulten]

Hi, I struggle with high fuel consumption (7,5l/100km roughly) and in the garage gas fumes are very obvious.

Could you pass what exactly parts I should replace? I guess some of them?
https://www.realoem.com/bmw/enUS/showparts?id=0422-EUR-05-2003-259S-BMW-R_1100_S_98_0422,0432_&diagId=16_0366

And last question will I struggle to do this by my self or will be pretty easy?