Bit of an odd bubbling noise...

[Fishtank]

So I was doing an oil change yesterday and while draining the swingarm, I heard a constant bubbling sound. I traced it, as best as I can tell, to the fuel pump area. It seemed like a steady sound of air leaking into the tank but there was no sign of any fuel trading places with it.

I searched the forum and only came across one other post asking a similar question and relating it potentially to a faulty fuel pressure regulator but there were no replies to it. I can understand if the regulator is failing to hold pressure and bleeding it back into the tank, but that shouldn't result in air being introduced into the system. I thought one option may be the tank vent valve being blocked causing a vacuum in the tank, but I tested the drain line and its clear (got a nice little octane buzz in the process :black_eyed: ).

My bike is a little stumbly around the 3000 RPM range but I have some troubleshooting planned to address that, just in case that may be connected.

Any thoughts from the experts?


Extra details:
2008 XB12ss
12,000'ish miles
K&N filter
Stock Exhaust & ECM
94 octane (Ethanol free)

 

[Outlaw]

See if the noise goes away when you remove your gas cap.

 

[Cooter]

Probably just the gas in the tank cooling off while the bike sits during its oil change and pulling in air through the vent like it's supposed to. Meh, you have other things to worry about than worry about that.

What Outlaw said in different words:up:

 

[34nineteen]

I've had 2 bikes that boiled fuel and it usually is a very faint bubbling, almost hissing sound. Its similar to when you heat up water on the stove, and the boiling just start. If its not negative pressure building in the tank, I'd check for overheating 2nd.

On my SS it was the rear head sensor that was failing, and the bike was overheating. The 1125 was just a hot beast. LOL

In some cases it will push fuel out of the breather tube and you'll see it dripping on the ground on the LH side of the bike.

 

[Fishtank]

Thanks guys.

34, what were your indicators of the failing heat sensor?

 

[34nineteen]

Thanks guys.

34, what were your indicators of the failing heat sensor?

Boiling fuel, bike felt warmer than normal, and the fan wasnt turning on after shutdown.

When I grounded the wire that normally went to the heat sensor, the fan turned on, so I realized it was likely the heat sensor.

 

[Fishtank]

Boiling fuel, bike felt warmer than normal, and the fan wasnt turning on after shutdown.

When I grounded the wire that normally went to the heat sensor, the fan turned on, so I realized it was likely the heat sensor.

My fan does seem to be working, it stays on for 2-3 seconds after a ride and its not that hot up here yet, 60-75*F. I'll look into the wiring diagram, take some temperatures and do some digging on it.

 

[Lusiphur]

I overfilled my tank for the first time ever the other week.

Man, these things sure do make a ****load of noise and stink like hell while it's cooling off when that happens.

You can actually see the gas sloshing around, almost like waves on a beach.

 

[njloco]

Don't feel bad, I did the same thing last week.

 

[Cooter]

Sooo, a guy named FishTank is worried about a bubbling noise?



SharkBait! Moohaha!

 

[Lusiphur]

HAHAHA now that is ironic.

Fishtank
Burn some fuel off and let us know if it goes away. I think mine took about 20 miles to drop the level far enough.

BTW, Buells with a stock ECM have a torque drop between 3200 and 3500 rpms depending on the engine. You might be feeling that.
American Sport Bike did a huge muffler Dyno comparison years ago. Attached are 2 Dyno's of stock setups. XB9 and an XB12 Dyno

XB9


XB12

 

[Fishtank]

Gee thanks Cooter, now this is what I'm going to think of when asking questions on the forum...

You, Lunatic, Silver, Lusiphur and the other senior members can sort out who is who, for some reason I imagine Lunatic as the red one.


Lu, I will have to check again after I fuel up but I haven't noticed the scary bubbling lately, may have been a one-off.

I doubt it is the torque drop, it just feels like it pulses when under steady load around 3-3500 and it can get stumbly in the idle and lower revs. If I roll into it, its smooth.

 

[34nineteen]

Thanks Coots, now all I can think of is that the OP has one of those diver/treasure chest aquarium things in his fuel tank.

 

[34nineteen]

Gee thanks Cooter....
You, Lunatic, Silver, Lusiphur and the other senior citizens.

Fixed it for you

 

[Fishtank]

Thanks Coots, now all I can think of is that the OP has one of those diver/treasure chest aquarium things in his fuel tank.

Yup, its my automatic Seafoam dispenser.

 

[Lusiphur]

Normally, I am the little blue fish in the upper left.
Quietly lurking, but give me a topic I am passionate about and I become the big mouth in the middle.

 

[Cooter]

Yup, its my automatic Seafoam dispenser.

Oh daym, that's funny for a whole bunch of reasons:tongue-new: