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brickme
Joined: 24 Jun 2012 Posts: 11
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Posted: Fri Jul 05, 2013 2:09 pm Post subject: Fuel Cap Leaking Fumes |
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Tried cleaning the rubber gasket and the mating surface, both of which looked discolored but it still smells around the closed cap and stinks up contents of the tank bag. Happens no matter how full the tank is. I did a quick search of the site and didn't find anything. Should I try replacing the gasket? Is there an issue of corrosion of the mating surface? Thanks in advance for sharing your experiences/solutions. _________________ '95 K1100LT |
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Scott_Anderson Site Admin
Joined: 05 Sep 2006 Posts: 3122 Location: Central Iowa, USA
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Posted: Fri Jul 05, 2013 6:03 pm Post subject: |
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I'd make sure that your tank vent line at the right rear of the tank is open. If the vent nipple is still connected to the engine block I'd seriously consider installing the "accumulator cup" for the tank vent and rain drain line.
It sounds like your vent might be restricted causing the fumes to come out the cap. When you open the cap, do you hear any type of air pressure/vacuum change, like a "whoosh" type sound. _________________ Ride safe.
1995 K1100LT 0302044
2017 FLHTK Ultra Limited
Garmin StreetPilot 2820
Garmin Zumo 550
Garmin Zumo XT
"One who does not ask questions is ashamed to learn" Danish proverb
1997 K1100LT 0302488(R.I.P.)
1997 R1100RT ZC62149(sold) |
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brickme
Joined: 24 Jun 2012 Posts: 11
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Posted: Fri Jul 05, 2013 11:48 pm Post subject: |
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| Scott_Anderson wrote: | I'd make sure that your tank vent line at the right rear of the tank is open. If the vent nipple is still connected to the engine block I'd seriously consider installing the "accumulator cup" for the tank vent and rain drain line.
It sounds like your vent might be restricted causing the fumes to come out the cap. When you open the cap, do you hear any type of air pressure/vacuum change, like a "whoosh" type sound. |
I identified the vent line at the right lower side of the bike between the rider and passenger footpegs, open to the atmosphere. No pressure or vacuum when opening the cap. _________________ '95 K1100LT |
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Scott_Anderson Site Admin
Joined: 05 Sep 2006 Posts: 3122 Location: Central Iowa, USA
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Posted: Sat Jul 06, 2013 10:42 am Post subject: |
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| brickme wrote: | | Scott_Anderson wrote: | I'd make sure that your tank vent line at the right rear of the tank is open. If the vent nipple is still connected to the engine block I'd seriously consider installing the "accumulator cup" for the tank vent and rain drain line.
It sounds like your vent might be restricted causing the fumes to come out the cap. When you open the cap, do you hear any type of air pressure/vacuum change, like a "whoosh" type sound. |
I identified the vent line at the right lower side of the bike between the rider and passenger footpegs, open to the atmosphere. No pressure or vacuum when opening the cap. |
Follow that line up to the underside of the tank, to make sure the air cup is installed. Normally that line only connects to the "rain drain" hole at the filler cap and not the internal tank vent.
part #5 in this pic
05 AIR ACCUMULATOR 16132307467 $2.26
here's a close up
If you have it and I'm beating a dead horse forgive me,,,, but there are 2 nipples on the underside of the tank, some US models have the vent line connected to the engine block with a check valve for emissions purposes. More often than not the check valve goes bad, and sometimes you can overfill your tank and endup with overflow gas into the engine....
If you want to clean gaskets you could also check the gasket that sets between the cap assy and the aluminum tank itself. Remove the 4 screws around the edge and the cap will come off. Just make note of the rain drain notch on the left side of the cap mount and the matching spot on the gasket when you put it back together.
I have noticed that same fuel smell myself from within my tank bag too, but usually it's only on the warm days of long riding, or if it's been setting in the sun at work. I figure that 'hey it's setting on top of a gas tank filler cap' I'm not surprised if it smells a little. _________________ Ride safe.
1995 K1100LT 0302044
2017 FLHTK Ultra Limited
Garmin StreetPilot 2820
Garmin Zumo 550
Garmin Zumo XT
"One who does not ask questions is ashamed to learn" Danish proverb
1997 K1100LT 0302488(R.I.P.)
1997 R1100RT ZC62149(sold) |
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brickme
Joined: 24 Jun 2012 Posts: 11
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Posted: Sat Jul 06, 2013 12:21 pm Post subject: |
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Scott,
Thanks a lot for the pictures and additional information. I am still having trouble visualizing the plumbing setup for the venting. Where does the "rain drain" hole at the side of the gas tank opening go to? Pulled off the side cover to follow the tubing up from the bottom but still can't see where it ends up, so would probably need to pull off the tank or additional bodywork. That's a little more involved for the LT than on the GS I used to have, so I may leave it for the dealer to check out when I have the brakes bled.
You mention "The gasket that sets between the cap assy and the aluminum tank itself." Those are the surfaces I cleaned previously, but only with a rag. I didn't get too aggressive on the tank side to prevent debris from dropping into the gas. I will work on it some more though.
The closed fuel cap stinks with a cold bike inside the garage, so I need to get it fixed. Here is a photo of the grit that develops between the aluminum tank mating surface and the rubber seal on the cap.
 _________________ '95 K1100LT |
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Scott_Anderson Site Admin
Joined: 05 Sep 2006 Posts: 3122 Location: Central Iowa, USA
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Posted: Sat Jul 06, 2013 1:33 pm Post subject: |
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In your picture of the open gas cap, remove those 4 phillips head screws and there is another gasket under the cap assy.
To see the tank vent "outlet nipples" you will need to lift up the rear of the gas tank. If you bike still has them there are 2 circlips that secure the rear of the tank.
Once you lift up the rear of the gas tank on the right side 4 or so inches from the rear forward there will be (2) 1/8" nipples that stick out the bottom of the tank.
1 is piped to the rain drain, which is "normally" connected to a hose that runs down the right side of the bike and hangs by the right foot peg plate.
The other nipple is piped to the internal tank vent point. Some US emissions version bikes have this nipple connected to a vacuum line that goes down to the top of the engine block behind the radiator. The intent was for the engine to draw "vacuum" from the gas tank, thus drawing the fumes/vapors into the engine. Historically the inline check valve can fail, or if you overfill the gas tank and get liquid gas up to the vent opening, you can end up with gas down into the engine mixing with the oil
The purpose of the "cup" is that it sets directly under the nipples and allows for any liquid leakage from either of the nipples to be drained down to the ground.
When you install the cup, you will disconnect both vac lines from the nipples. The line going to the engine block you will close off/cap/plug. Some owners have gone so far as to remove the line clear down to the block fitting(more involved than just capping line at the tank in the short term).
The other line that goes down the side of the bike you will then connect to the outlet of the "cup".
Pretty simple.
The only caveat to this modification is that now you are venting the gas tank to the open atmosphere, it will no longer be a "sealed" system. You can be more prone to smell gas.
I have done this mod on both of my bikes.
I have both bikes, gas cans, lawn equipment, and my boat all parked in my garage and have no noticable gas fumes that I can smell. Could there be another source of fumes in your garage?
How sealed up is your garage, air ventilation in/out. That can make a difference too. _________________ Ride safe.
1995 K1100LT 0302044
2017 FLHTK Ultra Limited
Garmin StreetPilot 2820
Garmin Zumo 550
Garmin Zumo XT
"One who does not ask questions is ashamed to learn" Danish proverb
1997 K1100LT 0302488(R.I.P.)
1997 R1100RT ZC62149(sold) |
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brickme
Joined: 24 Jun 2012 Posts: 11
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Posted: Sat Jul 06, 2013 2:28 pm Post subject: |
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OK, that all makes sense. I will see how far I can lift the tank by removing the circlips. I will check out the other gasket you mentioned too. Hard telling what was done to the bike, I am the 3rd owner and it sat for a while after the original owner passed on.
As for the garage, it is attached to the house, so with a car, lawn mower and the LT I leave a small garage window open year around to vent any fumes(not great for the winter heat bill). It doesn't smell until I get next to the bike, and then put my nose about 6 inches from the cap to verify that is where it is coming from. I understand many fuel systems have vents. Venting under the bike would be desirable over coming out the cap though, with the possibility of being breathed in behind the fairing. Had lots of bikes over the years but this LT is the first with this particular problem, so would like to solve it.
Thanks again for the followup! _________________ '95 K1100LT |
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Scott_Anderson Site Admin
Joined: 05 Sep 2006 Posts: 3122 Location: Central Iowa, USA
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Posted: Sat Jul 06, 2013 3:29 pm Post subject: |
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One other remote possibility could be that you may be getting some fumes thru the actual cap key lock assy. I can't say how that part of the cap is sealed as I've not had one apart. _________________ Ride safe.
1995 K1100LT 0302044
2017 FLHTK Ultra Limited
Garmin StreetPilot 2820
Garmin Zumo 550
Garmin Zumo XT
"One who does not ask questions is ashamed to learn" Danish proverb
1997 K1100LT 0302488(R.I.P.)
1997 R1100RT ZC62149(sold) |
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grant93 Flying Brick Rider

Joined: 23 Mar 2013 Posts: 238 Location: Victoria - Australia
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Posted: Sat Jul 06, 2013 9:43 pm Post subject: |
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Gidday folks,
Just lift the tank a little, pull it back a little, hold with one hand and with the other unscrew the two hoses on the left side that attached to the tank and just remove the tank, takes about a minute.. to easy.
I have often wondered what that plastic cup was that just seems to hung around there quite freely..
Ya learn something every day. Thank!! _________________ Cheers Grant
1994 K1100RS
1981 R100RS
1978 R100RS
1928 Chevrolet tourer
www.montythe1928chevrolet.blogspot.com.au |
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Tim (Midland Section) Flying Brick Rider

Joined: 08 Apr 2005 Posts: 960 Location: Pinxton, Nottingham, England.
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Posted: Sun Jul 07, 2013 7:36 am Post subject: |
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When I take the K in the van for holidays (SWMBO has arthritis & cannot cope with a fully laden bike these days) I always get a hint of fuel smell. Never found a leak. Tis less if the tank has 40 miles ridden from full. Always meant to investigate but can't be ar... bothered.
If I find anything, I will post. UK bikes AFAIK do not have the Vacuum bit to the engine. Have read here of modern fuels "eating" old pipes.
Either way a LOT less smelly than the old Norton.
If it bugs you, test with a match?  _________________ Regards Tim,
Grey haired riders don't get that way by pure luck
1996 Guzzi Cali3 LAPD
1972 750 Commando
G6HRN
#485 |
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brickme
Joined: 24 Jun 2012 Posts: 11
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Posted: Sun Jul 07, 2013 9:15 pm Post subject: |
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Yeah, the match test would solve my problem! Heh, heh.
Is that what happened to the Norton? _________________ '95 K1100LT |
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Stoked Steve Flying Brick Rider

Joined: 01 Sep 2004 Posts: 1402 Location: Virginia Beach, VA
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Posted: Sun Jul 07, 2013 9:23 pm Post subject: |
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The tank lift on the K is a piece of cake, once learned, you can do it in 30 seconds.
I had mine off many a time... _________________ Steve
Virginia Beach, VA
93 K1100RS Mystic Red SOLD
12 Suzuki DL650A VStrom |
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Eurocycleguy
Joined: 30 Mar 2013 Posts: 21
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Posted: Mon Jul 15, 2013 6:19 pm Post subject: Fuel fumes |
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I get a gasoline smell to my tankbag and contents also. I agree completely with the previous discussion on the venting, etc.
However I seem to recall, vaguely, that the gas cap lock cyclinder had been drilled for some purpose long ago.
I am not sure if I am confusing different beemers.
But I have been attributing the odor to this possible deed. _________________ 1967 SEARS (Gilera) 106SS
1974 Laverda 750GTF
(looks like I need something from the '80s in this spot)
1996 BMW K1100RS
Numerous others I wish I still had and couple that I don't |
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brickme
Joined: 24 Jun 2012 Posts: 11
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Posted: Fri Jul 26, 2013 9:51 am Post subject: Re: Fuel fumes |
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| Eurocycleguy wrote: | I get a gasoline smell to my tankbag and contents also. I agree completely with the previous discussion on the venting, etc.
However I seem to recall, vaguely, that the gas cap lock cyclinder had been drilled for some purpose long ago.
I am not sure if I am confusing different beemers.
But I have been attributing the odor to this possible deed. |
Interesting. Along that line of thinking(the cap being a possible problem), does anyone know if the cap itself has a venting function, or pressure pop-off? Just wondering if the cap could be faulty.
Could be unrelated, but I opened it today after sitting several days with the tank about 1/4 full and the underside of the cap was soaked with gas. So much so that while tilted open it started dripping into the rain gutter. That might stink up the tankbag. _________________ '95 K1100LT |
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hosehoundfr86 Mad Brick Rider
Joined: 17 Jul 2013 Posts: 122 Location: New Brunswick,Canada
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Posted: Fri Jul 26, 2013 5:41 pm Post subject: |
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| you can get a gas cap repair kit that replaces all the gaskets,, on you-tube there is a guy who shows how it's done,, (he is a bit vulgar ,, but he knows his stuff),, the only thing I don't like is that he uses "copper"anti seize on everything,, I like Aluminum based on aluminum parts,,,,Happy trails,,,, |
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Matthew Porter
Joined: 28 Sep 2013 Posts: 10 Location: England
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Posted: Sat Sep 28, 2013 5:03 pm Post subject: |
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Firstly let me introduce myself. I presently have two 1100LT's; one silver 1996 and the other blue 1997. My history is I had an R80Rt and then a K1. I liked the fairing of the former and the engine of the latter and when the 1100LT was introduced I knew this bike was for me. My first in 1993 in silk blue which I did 30,000 miles on in 12 months, the second was a 1994 in silk blue which I covered 23,000 miles in 12 months, the third was in 1995 which i kept for two years and covered 47,000 miles on. Circumstances altered, I no longer annually covered the miles I had previously and the 1997 LT I still have and it has 82,000 miles. Knowing that the parts would get harder to get for an older bike I bought my 1996 LT on ebay in 2008 with only 27,000 miles. The 1997 blue brick was I imagined going to become a "hangar queen" but far from it she still keeps going. The 1996 silver brick has 36,000 miles on it now.
My name is Matthew and I live in the south east of England approx 25 miles from London. And when I can I always try to get to the Dolomites in northern Italy. The mountains in summer are fantastic.
Previously I have replaced a couple of the foam gaskets - the gasket which sits under the filler lid - when they reach the end of their days and have ordered a replacement from the local Motorrad dealer.
A couple of days ago I discovered I have a fuel tank which is leaking fuel every time I accelerate. Basically the foam gasket has failed again. I know I can't purchase this item alone from BMW so I need to get a gasket set. The part number is:- 16 11 9 062 461 Gasket set.
Yesterday I learned the gasket set is no longer available from BMW. I tried three companies who deal in parts for BM bikes in the UK, James Sherlock, Motorworks and Motobins. All have told me that they haven't had any for a while and would only have sourced from BMW.
Before I go searching for a company to specifically make a new foam gasket to order does anyone know of company or individual who manufactures and supplies these things? _________________ Matthew
BMW K1100LT x 2 (1996 & 1997)
Eric Clapton said he wanted to quit guitar when he heard Jimi Hendrix play. I feel kinda that way when I see a genius riding a motorcycle. But then I kick myself and try and do better. |
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whyoldbill Flying Brick Rider
Joined: 12 Jun 2006 Posts: 440 Location: in the boonies, northwest of Columbus, Ohio
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Posted: Sat Sep 28, 2013 8:25 pm Post subject: |
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Max BMW still lists it:
http://www.maxbmwmotorcycles.com/fiche/DiagramsMain.aspx?vid=51748&diagram=16_0815
If they won't ship it to you, let me know. I can send it interoffice to my colleague in Bournemouth or another one in London.
BTW, Welcome to the forum. _________________ '02 - GL1800
The desired effect is what you get when you improve your interplanetary funksmanship - George Clinton |
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Matthew Porter
Joined: 28 Sep 2013 Posts: 10 Location: England
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Posted: Sun Sep 29, 2013 1:23 pm Post subject: |
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Very grateful to you. I will post again once I have had a response.
Cheers _________________ Matthew
BMW K1100LT x 2 (1996 & 1997)
Eric Clapton said he wanted to quit guitar when he heard Jimi Hendrix play. I feel kinda that way when I see a genius riding a motorcycle. But then I kick myself and try and do better. |
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Tim (Midland Section) Flying Brick Rider

Joined: 08 Apr 2005 Posts: 960 Location: Pinxton, Nottingham, England.
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Posted: Sun Sep 29, 2013 4:51 pm Post subject: |
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| Matthew Porter wrote: | Very grateful to you. I will post again once I have had a response.
Cheers |
One can use that part number/s to order from any UK BMW dealer (including car outlets) That's what I do, as the local bike dealers are not on my way home from work. _________________ Regards Tim,
Grey haired riders don't get that way by pure luck
1996 Guzzi Cali3 LAPD
1972 750 Commando
G6HRN
#485 |
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Matthew Porter
Joined: 28 Sep 2013 Posts: 10 Location: England
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Posted: Mon Sep 30, 2013 5:19 am Post subject: |
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| Tim (Midland Section) wrote: |
One can use that part number/s to order from any UK BMW dealer (including car outlets) That's what I do, as the local bike dealers are not on my way home from work. |
Right, that is ordered, now we'll see whether the stock is in their parts department.
Many thanks for offering to arrange to get it to me. Max were giving a shipping price to the UK of $47. Luckily I have family in CT, NY and FL so have asked for the gasket set to be sent to the first for the $10 domestic shipping charge.
Tim the problem is unless the dealer has stock, which now is a bit unlikely due to how long the K1100 has been out of production, BMW UK don't have any and neither do BMW AG. Unfortunately the parts stock situation cannot be seen with an overview of all so I'd have to contact every Motorrad dealer in the UK which is a bit long-winded. And now with ethanol being added to petrol in Europe it would appear the older BM bikes fuel pipes and anything rubber in contact with the presently available fuel is deteriorating so the thing I have encountered will become more pressing for more and more owners.
I did find a company RAM Gasket Solutions in Redruth, Cornwall UK www.ramgaskets.com who will manufacture and supply a minimum order of just one unit. But didn't pursue that as the part appears to be available at MAX BMW. One contact to hold in the back-pocket if needed in the future.
Grateful to you both. _________________ Matthew
BMW K1100LT x 2 (1996 & 1997)
Eric Clapton said he wanted to quit guitar when he heard Jimi Hendrix play. I feel kinda that way when I see a genius riding a motorcycle. But then I kick myself and try and do better. |
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