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Fuel Leak?


tcausey

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Hello All-

 

Strange thing happened this afternoon. My '02 R1150RT has been sitting for 2 or 3 weeks on a battery tender. I normally ride at least once or twice a week all year so it's a bit odd for it to sit even that long here in Atlanta.

 

I went to the garage to start it up and liquid started puddling up right under the catalytic converter part of the exhaust. It was dripping and smoking as the exhaust started to get hot. I turned to the bike off and realized it was fuel. My first thought was a busted fuel line or something (which it may be) so I took the RIGHT tupperware off and check the QD (they're a bit further forward than the leak it seems) and while there is a ever so slight sign of leaking QDs, it really looks like a leak somewhere near where the fuel lines run under the airbox. (i do have a new set of QDs I plan to put on anyway (my 2nd replacement set . . . and yes they are good ones this time.)

 

I can clearly see wet fuel on the side of the transmission housing down and to the left of the QDs because it dried as I was looking at it. I start it up again to see it actually leak so I can find it and no leak . . . at least not that I can see yet and nothing that was as significant as when I first started it. I'm going to let it sit for a while again and keep trying.

 

I guess my question is: Could it been under high pressure or something with cold weather that would have caused a temporary problem?

 

Thank you.

Troy

 

 

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The fuel distributor and pressure regulator are forward of the air box and above the transmission. Much of this assembly is plastic, but includes a metal pressure regulator that is sealed with O-Rings. While it could be that the O-Rings are leaking under pressure, it could also be a crack in the distributor.

 

If there was an obstruction in the return line or if the return QD was disconnected the pressure can get quite high, perhaps twice the usual 43 psi.

 

Not sure what to say except that you need to figure it out before riding it (obviously).

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Got it. Oh yes. I will figure it out before riding. This is very helpful. What's the best way to get to it all? Removing tank I assume? Anything specific I need to know?

 

I'm pretty handy and I've got the remove the tank anyway to bleed the ABS unit, etc., but I don't want to bite off more than I can chew. I'll take any advice.

 

Troy

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Many here know more about getting to the regulator but in most cases you have to lift or move the rear frame although I don't think you need to remove the swing arm or transmission. Ugh.

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Did you try turning the key to on with the right side cover off? I don't think you have to actually start it to pressurize the system. Under pressure, you might get a better idea where it is squirting from. If I were the one who had replaced to QDs, I'd suspect I'd buggered up the ends of the hoses or not tightened the clamps enough when I installed the new ones.

 

 

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Did you try turning the key to on with the right side cover off? I don't think you have to actually start it to pressurize the system. Under pressure, you might get a better idea where it is squirting from. If I were the one who had replaced to QDs, I'd suspect I'd buggered up the ends of the hoses or not tightened the clamps enough when I installed the new ones.

 

 

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That's a good point. When I've measured fuel pressure, the couple seconds the pump runs when you turn the key on pressures the lines to about 40-44 psi.

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I did try turning the key on (and also starting it) with the right cover off and the leak seemed to vanish. At least an obvious one vanished. there was enough fuel the during the first leak that it was serious and it makes the most sense it was at the regulator location based on where things were.

 

 

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If anyone can provide me with a rough explanation of the best way to the regulator to at least inspect it, I'd be grateful. In the meantime, I'll keep searching as I'm sure it's here.

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Morning Troy

 

The usual & most common place for a fuel leak (ON A COLD BMW 1150 BIKE) is the "O" ring in the pressure side quick disconnect.

The fuel can run out about anywhere under the bike as it can migrate down a fuel hose & drip off the hose low point or drip off of another engine feature.

What usually happens is the quick disconnect "O" gets a little old & hard so shrinks a bit & doesn't seal real solid when cold.

What can happen is when the bike sits over night or longer a slight vacuum forms in the fuel tank & fuel hose system. Just enough to suck a degraded "O" ring slightly off it's sealing.

When the cold bike is keyed-on the "instantly pressurized" fuel gets by the "O" ring & leaks out under the bike.

After a sort leak period the pressure builds enough to seat & swell the "O" ring & it seals again for weeks or months on end until just the right circumstances for it to unseat or shrink again & you have another leak.

The place to start on your bike is to replace both quick disconnect "O" rings. Either use BMW dealer supplied "O" rings or take an old (removed) one to your local auto parts store & match them up.

 

Also-- when re-assembling the quick disconnects be sure to hold the quick disconnect trigger all the way down all the way through the quick disconnect re-coupling. If that trigger isn't held down through the insertion there is a chance you can nick the "O" ring as the quick disconnect goes together.

 

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Thanks D.R.

 

I can definitely do this. Which one is the pressure one? I'm actually going to replace the QDs (and perhaps hose) most likely as the "bottom" one is leaking a little bit at the hose clamp. The pressure could have forced a serious leak at the hoseclamp for the first minute or so I guess. It was just a LOT of fuel yesterday, but given that it's not leaking so profusely now, perhaps it's not at the regulator.

 

I'm a bit nervous about the regulator because it appears to be considerable surgery to replace which means I should do the splines, etc. while I'm under it.

 

Since Winter is just starting here in GA, perhaps I'll do the QDs and then see if I get leaks anymore and then worry about the other problem as I'll still have time to fix it before real riding season.

 

 

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As usual, DR has provided an excellent diagnostic roadmap with detailed explanation.

 

The lower plastic line is high pressure line coming from the tank to the distributor. The upper is the return hose back to the tank.

 

When I replaced my QDs the hoses were very hard and had to be clamped very tightly because of that. When I had the in-tank fuel hose failure last summer, I replaced all the internal and external hoses.

 

It might be a better plan to either:

 

1) just replace the o-rings, or

 

2) replace the QDs and external hoses.

 

Some other time, when you feel ready for it, you should plan to overhaul the inside if it hasn't been done in 5 years.

 

RB

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Thanks RB. I had been reading about your in tank hose failure. I have replaced the filter in the tank 2 years ago and before spring, I was going to do it again when I remove the tank for ABS unit bleeding. Perhaps I'll do all internal and external hoses then.

 

Looks like I have a plan for the short term. Thank you both immensely.

 

 

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There have been several reports of these bikes leaking at start up on cold days. Doesn't happen on warm days, and doesn't happen except at the first start of the day. The cause has almost always been the hose clamps at the QD, and not the QD themselves. Snugging up the clamps has fixed the problem. Of course, if you already have a leak from the QD itself, then the o-ring may have been damaged when the QD were reconnected at some time in the past.

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flars. The more I inspected it and with the input from you, DR and Roger, this is the only clear explanation of what happened as I had a slight leak from the QD hose clamp area anyway. I actually replaced the metal OEM disconnects with Jiffy-Tite ones that I had in my toolbag and then make sure the clamps were nice and tight. No leaks at this point and I'll just keep watching over as I ride and start it over the next couple of months.

 

In March I'll replace the hoses with some other service items.

 

thanks again.

 

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