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1Back to top Go down   K1100LT Fuel Tank  Empty K1100LT Fuel Tank Tue Jun 29, 2021 7:36 pm

brickrider2

brickrider2
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I returned from the MOA rally a wiser rider.  That's a good thing because I have an issue with the tank that has me puzzled.  The cap is wet and has soaked the underside of the tank bag.  At one point on a very hot afternoon, the engine stopped abruptly.  It only returned to life after I opened the cap.  I thereafter was obliged to carry the tank bag behind me - not the optimal spot, for sure. But to return to the point of the engine stopping, if there is inadequate venting of the tank, why would fuel be escaping around the edges of the cap?  Mind you, this only happens when the tank bag is in place over/on the cap. That suggests to me that the seepage around cap and the engine stalling are related.  
By way of background, I should say the cap was apart within the last year for a rebuild.  However, there were plenty of miles ridden post-cap rebuild without incident.  The engine stopping and the weeping/seeping fuel cap are recent wrinkles in my relationship with the Big Red Beast. 
Any ideas, doubts or WAGS?  What's goin' on?   scratch


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1996 K1100LT
    

2Back to top Go down   K1100LT Fuel Tank  Empty Re: K1100LT Fuel Tank Tue Jun 29, 2021 9:13 pm

RicK G

RicK G
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I was reading yesterday that it's getting fairly hot around your place, have you considered the possibility of a vapor lock due to hot fuel.
One thing I found recently on my new to me K1200GT was that a wasp had taken up residence in the breather thus making vapor escape from the filler cap when pressure built up in the tank. I was getting a faint smell of fuel when I was stopped.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

3Back to top Go down   K1100LT Fuel Tank  Empty Re: K1100LT Fuel Tank Tue Jun 29, 2021 10:23 pm

robmack

robmack
Life time member
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There are two vents in the tank terminating in the lower right side.  One is to drain rainwater that collects around the gas cap.  The other comes from the Burrito just under the gas cap that vents air and fuel overflow should the fuel and tank become hot. If the tube is blocked the only escape path from fuel is from the Burito which means it leaks out the cap.   It's possible the vent tube is blocked in your tank.  Use compressed air to blow out any possible debris.  Ir use a flexible but stiff wire to poke up the tube and dislodge any possible debris.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

4Back to top Go down   K1100LT Fuel Tank  Empty Re: K1100LT Fuel Tank Wed Jun 30, 2021 12:03 am

RicK G

RicK G
admin
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If you use compressed air to clean the hole make sure the cap is open because I have seen how more than a few lbs of compressed air can reshape a tank, they tend to become a very different shape from the what they were and they don't fit back on the bike.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

5Back to top Go down   K1100LT Fuel Tank  Empty Re: K1100LT Fuel Tank Wed Jun 30, 2021 3:45 pm

moriarti

moriarti
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Life time member
Hi I replaced both pipes on mine just to be sure  Very Happy


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1984 k100 rs red/black VIN  0004449
    

6Back to top Go down   K1100LT Fuel Tank  Empty Re: K1100LT Fuel Tank Thu Jul 15, 2021 3:22 am

brickrider2

brickrider2
Life time member
Life time member
I pulled my fuel tank and checked the hoses that connect to the underside.  Both are clear.  The hose that connects to the pipe nearer the forward end of the tank has a valve more or less in the middle, and the other end attaches to a fitting on the crankcase. Is this connection correct? I don't really understand why it should be connected there....  I separated the valve from the hose and found that I could blow through it.  It has a very narrow opening, so it cannot pass a high volume of air,  but it seems sufficient for venting the fuel tank.  
Perhaps I'm over-filling the tank?  I estimate that I leave about 1 1/2 inches of air between the surface of the fuel and the filler opening.  Could that be too little?  This seems unlikely, as I've filled loads of tanks to roughly the same level without issues.  I'm tempted to pull the hose off the sump fitting and instead route it down and back to the rear of the bike.  With the valve in the hose there seems to be no possibility that contamination would find it's way up the hose and into the fuel tank.  Alternatively, I could resign myself to touring without a tank bag, as the cap doesn't "leak" when there is no bag resting on it.  I'm not keen on that as I find tank bags to be very convenient. 
Otherwise, I'm out of ideas.
I was unable to find a burrito in the tank.


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1996 K1100LT
    

7Back to top Go down   K1100LT Fuel Tank  Empty Re: K1100LT Fuel Tank Thu Jul 15, 2021 4:09 am

moriarti

moriarti
Life time member
Life time member
Accepting that the cap is without fault, maybe the weight of the bag and pressure from the rider leaning on it IS the cause of the problem. As a simple test make a ring from firm rubber or some such about 3cm thick that fits round the cap fix to tankbag with double sided tape. The idea is to remove pressure from tank cap. Just thinking outside the box. scratch


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1984 k100 rs red/black VIN  0004449
    

8Back to top Go down   K1100LT Fuel Tank  Empty Re: K1100LT Fuel Tank Thu Jul 15, 2021 6:58 am

92KK 84WW Olaf

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@moriarti wrote:Accepting that the cap is without fault, maybe the weight of the bag and pressure from the rider leaning on it IS the cause of the problem. As a simple test make a ring from firm rubber or some such about 3cm thick that fits round the cap fix to tankbag with double sided tape. The idea is to remove pressure from tank cap. Just thinking outside the box. scratch
The OEM tank bag does not sit on the cap itself to prevent this very problem. The very thick base part stays in place on the tank for refuelling and has a hole in it to open the cap.

Using a different tank bag sitting directly on the cap is going to depress the cap and possibly flex and intermittently break the seal.

The cap does NOT vent the tank at all, the internal pipe vent does it. I have and do inverted the tanks if I have them off the bikes and they don't leak through the cap on me.


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 40,490 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 42,640 miles.

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

9Back to top Go down   K1100LT Fuel Tank  Empty Re: K1100LT Fuel Tank Thu Jul 15, 2021 7:56 am

Laitch

Laitch
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@brickrider2 wrote:With the valve in the hose there seems to be no possibility that contamination would find it's way up the hose and into the fuel tank.  
 
I was unable to find a burrito in the tank.
Your valve-in-the-hose theory is right on the money except if the valve fails—which it does. Smile   The valve/hose setup leading to the crankcase was developed to meet California emissions standards but can cause excess pressure problems in fuel tanks. There is a service bulletin explaining the condition. Part of the remedy is removing the valve and routing the hose as you have described. The other part is blocking the crankcase port. A short hose fitted to that port then doubled and zip-tied will do the trick.

The buritto is difficult to find unless a mirror and flashlight is used or you have stalked eyes like a lobster. It's fastened to the tank's ceiling just forward of the fuel tank opening.


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1995 K75 81,000 miles
K1100LT Fuel Tank  Usa-lo10
    

10Back to top Go down   K1100LT Fuel Tank  Empty Re: K1100LT Fuel Tank Thu Jul 15, 2021 1:47 pm

Shep

Shep
Platinum member
Platinum member
Describe what you mean by the word "Burito (Burrito)"  please.
Shep


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Model        Production Date/Serial Number
K100RS      1984 July/ (F0040448)
K100RS      1986 Dec/ (H0142581)
    

11Back to top Go down   K1100LT Fuel Tank  Empty Re: K1100LT Fuel Tank Thu Jul 15, 2021 2:49 pm

robmack

robmack
Life time member
Life time member
Forward and just under the gas cap is an aluminium cylinder with crimped ends, used to handle fuel overflow. Its shape reminds you of a burrito. Therefore, it has that nickname.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

12Back to top Go down   K1100LT Fuel Tank  Empty Re: K1100LT Fuel Tank Thu Jul 15, 2021 5:12 pm

Shep

Shep
Platinum member
Platinum member
Thank you.
I now have a better idea of what I am looking for.
Shep


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Model        Production Date/Serial Number
K100RS      1984 July/ (F0040448)
K100RS      1986 Dec/ (H0142581)
    

13Back to top Go down   K1100LT Fuel Tank  Empty Re: K1100LT Fuel Tank Fri Jul 16, 2021 5:48 pm

brickrider2

brickrider2
Life time member
Life time member
Using my dental mirror I was able to see that in my tank.  It's  purpose eludes me. Be that as it may, peering through the port reminded me again of what a complex fuel tank K-bikes have.  There are a lot of complicated bits within.


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1996 K1100LT
    

14Back to top Go down   K1100LT Fuel Tank  Empty Tank Fri Jul 16, 2021 10:46 pm

daveyson

daveyson
Life time member
Life time member
I'd attach a dry hose to the barb for the fuel return hose and blow air in to feel or hear if it comes out the vent hose near the right foot peg plate. 

I think of the burrito as a cavity for the tank vent pipe to minimise the pipe scooping up sloshed fuel. It has a hole on top to minimise pressure differences inside and outside the tank, and a hole in the bottom so that any fuel sloshed in can drain out.


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11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

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