80F day,
40 mile ride - nothing strenuous - it did involve some stop and go traffic about half way through.

After I parked the bike (engine off), I heard a whine coming from what I believe is inside the gas tank.
The whine was intermittent lasting between 5 - 10 seconds but cycled on and off for over 5 minutes.
Do I have a problem or is this normal?

Cheers, M

How warm was your gas tank after the ride? Sometimes going into a cooler area like your garage with the tank being warm can cause the whine from changes in temperature. Kind of like when you put a fuel container in the sun and open the lid, you get a rush of fumes from the fuel expanding from the heat. Could be the reverse happening.

caferacer62 wrote:How warm was your gas tank after the ride? Sometimes going into a cooler area like your garage with the tank being warm can cause the whine from changes in temperature. Kind of like when you put a fuel container in the sun and open the lid, you get a rush of fumes from the fuel expanding from the heat. Could be the reverse happening.

The tank was quite warm, but it sounded a bit more electrical than that.

Still,, good point...

Cheers, M

It's whining because you haven't been nice enough to your bike lately. Treat it to an evening at a five-star hotel of its choice and the whining will stop (temporarily).

do you carry a pillion > ?
it could be her

I have kawasaki 250 in my shed that does that when I park it in the sun,(that would be about 2 years ago where I live).
I have never been able to pinpoint exactly from whence it came.
RT

The only thing I know of in the gas tank is the fuel pump. I would not think that should be going after you turn it off but under the gas tank is a mess of wiring going to the ecu. If it happens again see if you can pinpoint whether it is inside the tank or under. That will give you a starting point if you think the noise is electrical.

After your next ride (and the noise is there) open the fuel tank to see if the noise stops. If it does, maybe the vent in the cap is a bit blocked?

Worth a try at least...

On some cars, the fan continue to cycle until the engine cool down. (even if the ignition is turn OFF)
It could be the cooling circuit being modified to achieve this function. (I don't believe BMW had this system originally installed)
When the fan is on its way, it turns really slowly and whine.
Have you checked it lately?
With the fairing it's difficult to pinpoint if it comes from inside the tank or under the tank.
Maybe it's the relay inside the temperature monitoring unit....

CF

Crazy Frog wrote:

When the fan is on its way, it turns really slowly and whine.
Have you checked it lately?

CF

The fan spins freely - or did at least a few weeks ago. I changed the radiator.
But, I did note that when the fan kicked on in traffic, that it didn't sound convincing.

Definitely, the bike is getting hot and possibly vapour-locking. I have a couple of harder starts during my run yesterday.
The Pichler fairing seems to keep the bike hot - but being new to a K bike, I don't know what is normal.

I would have gone with the fan cycling on and off as the bike cooled down - that was the type of electrical noise it made - like a motor running - but I didn't hear the chop of the fan, just the whine of a motor.

Is the fan re-buildable? or should I source another?

Cheers, M

Let me add to this a little as Blakey mentioned the vent pipe.

When I fill the tank, as soon as I open the cap there is a pressure exchange. I don't know if the tank has too much pressure if if it is a vacuum - but there is definitely an exchange of gasses between the outside air and the tank.

I did change the vent pipe and saw some gas drip after overfilling the tank one time.

History:
This bike was a low mileage bike. 13,000 on the clock (supposedly). Certainly the last owner only did 1,000 miles between 1988 and me buying the bike in Dec last year (2011). I took off date-code 1991 tyres when I got the bike with the rotors and foot pegs looking like new.

Thus far I have changed the radiator (old one leaking) and replaced most of the rubber on the bike, ditto fluids. Re-built oil/water pump, greased all splines, new air filter et al.

I'll put some compressed air through the vent pipe to check for a blockage. I'll connect the fan to 12v to see if that runs OK.
Thereafter, I'm at a loss...

So the whine is not the fuel pump going on for some reason.

yankeeone wrote:So the whine is not the fuel pump going on for some reason.

I don't know that - as stated, the sound was easiest heard at the tank, but as Bert pointed out, there's a lot of fairing to mask the origin of a sound.

The big thing for me is that this is not a normal sound - so time to strip the bike down and have a look around

You can hear the fuel pump when you first push the start button and see if it sounds the same as the new noise.

Moto Smith wrote: I did change the vent pipe and saw some gas drip after overfilling the tank one time.

Do you have hoses connected directly to the vent/overflow/drain stubs underneath the tank,
or do you have a plastic "cup" attached to the frame underneath these stubs?

Inge K.

Inge K. wrote:

Do you have hoses connected directly to the vent/overflow/drain stubs underneath the tank,
or do you have a plastic "cup" attached to the frame underneath these stubs?

Inge K.

Hoses, I renewed both before Christmas - I was particular about the way the tank went on so as not to kink the hoses.

Another tid-bit of info - sorry I'm a little scatter-brained at the moment...
The bike didn't hold idle very well when hot in the stop and go traffic - It kept falling off the rpms.
Normally, the bike starts just as my thumb gets close to the starter button and purrs like a kitten on tick-over.

I'm going to repeat the ride this afternoon (same sort of temperature) as I have some groceries to get from town - I'll report back.

Other than that, the bike is looking and riding great.

I have two weeks before my first camping trip of the season.

Cheers, M

Moto Smith wrote: I was particular about the way the tank went on so as not to kink the hoses.

It was this i did have in mind, reading a lot about problems due to hoses getting kinked on US models.

If you fit the "cup" part # 16132307467 it`s lot less hassle when moving the tank on and off.
(and only one hose from the cup and down behind the footpeg bridge).

Inge K.

OK, second ride - a little cooler, but not by much.

First thing - a hard start.
Three x 3 second starter bursts - not normal for my bike.

The ride:
5@3750rpm 20 miles each way.

Nada - nothing- zilch!

Idled just fine - no noises. I even let it sit for a while, nothing - BUT no fan either.

I hate miracle cures, as they can just as quickly become uncured - generally around the middle of Utah or Kansas.

I'm going to check the fan this coming Sunday.
Other thoughts...
Fuel pump or filter.
How do these present when they are on their way out?

Bike rides fine in all gears at all revs.

Cheers, M

yankeeone wrote:You can hear the fuel pump when you first push the start button and see if it sounds the same as the new noise.

The mystery noise was much louder - it could be heard 20 ft away (by an aging blacksmith!).

Cheers, M

where is your cat ?

What's the difference between your dog whining at the front door and your missus whining at the back door ?

If you let the dog in it'll shut up !

So here are some thoughts.

If the fan was suspect, (and I didn't hear it on the second ride), then the other issues would have presented themselves - poor tick-over, hard start (even when warm) and the mystery noise.
None of these were present during the second ride.

If there was a fuel delivery problem on ride one, would the bike have run leaner and therefore hotter causing an issue. Idle issue...

What does a vapour lock in the fuel system present like (sound?)

I had to shoot the cat as part of a problem-solving for another bike - so the cat is out.


Cheers, M

I see that your bike has 83-85 footrest bridges, could it be that you also got a older fuel tank?
Is it attached to the frame by two circlips or a single bolt?

The older tanks did have a noisy one way valve.....what I have in mind is that maybe your FPR
is acting up and release the pressure bit by bit when parked and the valve making noise.

And a malfunctioning FPR could give to low fuel pressure and make the engine run lean.

Inge K.

Dennis wrote:What's the difference between your dog whining at the front door and your missus whining at the back door ?

If you let the dog in it'll shut up !

While having drinks with some Australian servicemen while on detachment, one said to us We can always tell when one off your pomme jets have come in cause we can still hear the whinning after the engines have shut down.

BIG D

Inge K. wrote:I see that your bike has 83-85 footrest bridges, could it be that you also got a older fuel tank?
Is it attached to the frame by two circlips or a single bolt?


Inge K.

Ahh, that's only on the left side - the other side is different. - I think that this is an 85 to 91 type of bike.

I have two clips at the rear of the tank.
I have 4 lines to the tank.
1.)Vent from gas tank cap to rear foot-peg (overspill)
2.) Over-pressure vent to crankcase
3.) fuel out to injectors
4.) return fuel - comes to top of tank in front of cap

I would like to know how the tank breaths as I believe I have a vacuum in the tank.

Cheers, M

Moto Smith wrote:1.)Vent from gas tank cap to rear foot-peg (overspill)
2.) Over-pressure vent to crankcase

#1 (rearmost stub) is rain water drain, from a small hole on the left side of the cap flange.
#2 (frontmost stub) is the vent. and overfill........to crankcase .

#2 connected to the crankcase is US only............Euro models have the earlier mentioned "cup".
On the US models it`s also a check valve on this line (at least on the K11`s) which could make noise.

This thread might be some interesting reading for you.

Inge K.

Inge K. wrote:
#1 (rearmost stub) is rain water drain, from a small hole on the left side of the cap flange.
#2 (frontmost stub) is the vent. and overfill........to crankcase .

#2 connected to the crankcase is US only............Euro models have the earlier mentioned "cup".
On the US models it`s also a check valve on this line (at least on the K11`s) which could make noise.

This thread might be some interesting reading for you.

Inge K.

Thanks Inge,

It's nice to know that someone else had this problem.
I'll check the vent lines.
As stated earlier in this thread, I do get a short hiss when I open the gas cap, even a day or two after riding.
I do not smell gas after the hiss so I am presuming that the tank is vacuumed and that the air is going in, not coming out.
The lack of partial (air) pressure within the tank would cause the gas to vapourize at a lower temperature.

I'm going to check that the fan is working and check the vent lines. I'm also going to have a good look at the cap - as that is the air into the tank system.
I may re-route the vent line to a cup and get rid of the check valve along that line.

I'm thinking that the fan didn't work as it should, causing a heating of the gas lines and tank. The tank had 120 miles on it so 2/3 used and maybe in vacuum. A small vapour lock caused my idle RPM to fall off and also caused hard starting - even when warm.

And if that doesn't do it, I'll look at the fuel filter and FPR.

Cheers, M

Ok, this from Max BMW parts web site

16111453641 FILLER CAP 0.74 1 $210.54

This cap does NOT come with a lock cylinder and key. Must be purchased separately. Found in most cases in Main Group 51. We recommend this filler cap.

06 16112309403 FILLER CAP - KAT/SHED 0.93 1 $210.54

This cap does NOT come with a lock cylinder and key. Must be purchased separately. Found in most cases in Main Group 51. This cap has been known to not vent properly, causing a vapor lock and your machine to not run. We do NOT recommend this cap.

The conclusion - at least for this bit.
I am not the first person to take a look at my gas cap it appears. Someone previous to me had taken the valve off the cap and then replaced it. In replacing it, they failed to get the two cast iron knubbins at the end of the lock into the receivers of the cam piece that operates the latch.
I have about 1/16 groove where the cast iron knubbins have been sliding over the bottom of the cam receiver.
Further, there is a almost complete crack around the cap just above the lower seal.
The tightening of the three (triangular positioned) screws on the ill fitting lock/cam combo seems to have caused cracking over time.
I could see me standing at a gas station some time in the future with the cam not working if I hadn't have found the crack.

That's how I discovered the blurb about some caps causing vapour locks from Max BMW.

So currently the K is grounded pending a new cap and I'm back on the 650 singles.

Cheers, M

If anyone would like photos of the offending parts I would be happy to take them, otherwise I'll leave it be.