Water in the gas tank

[johngellis]

I continuously strive to keep the r1150r running as smoothly as possible.

For a couple of years I have noticed it seems to run differently even when out on the same ride and wasn't sure if it was just my imagination or tiredness. Eventually I realised that it was smoother when the gas tank was full than when going towards empty. At this point I was thinking it needed a new fuel pump.

I was discussing with a BMW club member and he remembered an incident where he had water in the tank caused it to run very roughly when close to empty.

Since I have never completely emptied the gas tank and the bike is 12 years old I thought I would give it a shot.

WARNING empting a R1150r tank is an extremely messy process. I ended up with gas all over the garage floor. I used a pipette with a rubber ball to get the last of it out. I left it out in the hot sun for a couple of hours to dry it out.

The operation was successful and the bike is running much smoother now, and cold start and cold tickover is much better. I guess you don't need much water in the tank to cause a problem.

The other point of interest is that the tank actually holds 5.5 US gallons. I just verified this on filling it.

[towerworker]

Glad you were able to get the problem resolved. Fuel pickup is not totally on the tank bottom although there is the "tip over" procedure to get some of the fuel from the left side of the tank to the right where the pickup is. Handy when you run out before you get to a station.

[AZBMWRIDER]

How does the seal on the fuel tank cap look ??

[kirby]

5.4 gal Usable!

[peels]

most ive ran down to... ahem, ran OUT at a stoplight, and then refilled to was: 5.3. I did NOT know about the "tip" procedure to slosh gas over to the side lol Pushed the bike 2 blocks.

I had water in my gas issue once, because drain line to canister was clogged. Noticed when my kids washed my bike for me, the next day i got gas, there was a puddle next to the fill cap when I opened, and it drained right into the tank. I watched it happen. Since removed canister, line drains to beneath the bike now. picked with weedeater line and Blew out that hose with air.

no problems now.

[lcarlson]

I think I would've tried a can of dry gas before going through all that....

[CycleRob]

johngellis, There are simple explanations for the weaker performance when the tank is near empty, especially if you, like me, are essentially forced to use 10% Ethanol gasoline.
1--Ethanol additive readily absorbs all water and water vapor that enters your bike's fuel tank -AND- the water entering the fuel delivery truck (tank+hoses) and possibly the worst of all, the service station's underground fuel tanks.
2--If you seldom ride your (Black?) bike and it sees many hours of parking lot sunshine, the fuel would loose potency through normal vapor loss.
3--Riding in the rain frequently, especially if the charcoal canister was removed, would invite more water and water vapor into the fuel tank.

Now about that canister (the bold text to connect with the response):

I had water in my gas issue once, because drain line to canister was clogged. Noticed when my kids washed my bike for me, the next day i got gas, there was a puddle next to the fill cap when I opened, and it drained right into the tank. I watched it happen. Since removed canister, line drains to beneath the bike now. picked with weedeater line and Blew out that hose with air.

The water drain line from the hidden exterior of the under fuel cap area does NOT (should NOT) go to the canister! It goes down to the right footpeg area "street drain". It's welded in place, small diameter, curved steel line inside the fuel tank frequently gets plugged up by road dust/dirt and internal rust that develops from stagnant rain and wash water. When it is plugged, rain/wash water will not drain away on the side stand like it's 9 O'Clock position was designed to do and the really disturbing water wave addition peels noticed happens all too quickly. Credit peels thinking for using weedwacker plastic line to poke out the crud deposits. I struggled with the much stiffer .028" safety wire which jams easily in the curves and is not as slippery or flexible as the plastic cutting line.
When you remove the charcoal canister, because it's ugly, damaged or you think it is not needed, the vapor vent line from the fuel tank is connected to the street drain line where it can and will inhale water vapor with temperature changes. It will even inhale liquid water if you ride from a hot sunny road into a cold rainy downpour while on the highway when the temperature change causes the steady internal fueltank pressure reduction.

The 3 lines going to the canister are:
Top--to the solenoid purge valve.
Middle--to the fuel tank VAPOR line.
Bottom--to drain liquid fuel from a fueltank overfill to the street drain hose.

The fuel canister gets destroyed by rain/wash water when the PO/Owner/Mechanic errantly swaps the correct hose connections at the two plastic male connectors that were stupidly placed right next to each other by the factory, ensuring that they will be mixed up, even by factory trained BMW mechanics!! To check for the correct hook-up, blow thru each line that goes toward the fuel tank. One will give increasing back pressure as if you were inflating a large balloon and should be connected to the line going to the canister center port. The other one will hiss (or spurt water drops) in the closed fuel cap area and it connects to the downward routed street drain hose. This borrowed and modified pic depicts my advice:


For non-ABS bikes:


My 2002 R1150R ran beautifully with it's charcoal canister correctly in place for almost 8 years and 63,874 miles.


Hopefully the topic was enhanced and not highjacked.