I'm smelling fuel...

[mac]

But not seeing any. I smell it at stoplights sometimes, and when I remove the cover from the bike in the morning.

I've sniffed around the bike a bit and can't seem to find a spot that smells way more strongly than any other.

I replaced the supply-side fuel line last year, as it was cracked near the tank nipple. I've got the corresponding new return-side line sitting on the toolbox, but haven't replaced it yet because the access to the fuel pressure regulator seems like a not-so-fun job.

I doubt I've got a leaky tank, as the bike is pretty pristine. Nothing too stinky along the fuel rail/injectors.

Any other places I should look hard at?

[david_hawkins]

Well.. I just fixed my 'new' 87 K75 tank cuz it was leaking in the back left corner along the seam of the tank.. check there.  I had a local VERY experienced radiator shop guys weld/epoxy/line the tank.. After having gas in the tank for a week, no leaking..

A couple of years ago I had the same issue with my R bike smelling of gas.. found it was the fuel lines also.. I replaced the leaky ONE.. then not a week later the other line was leaking.. then I replaced ALL the lines.. both inside and out.. When I inspected them after the replacement, I noticed longitudal cracks along the inside of the fuel lines.. Just used 5/16" multi fuel line for the auto parts store with fuel injector line clamps..

[Lawrence]

The fuel line seems very prone to splitting near the nipple on the underside of the fuel tank.  That hose clamp is also a PITA to access when you must remove the tank.  I have been considering those "quick disconnect" things.  The fuel line is very short though, and that make me wonder if it would be practical for this application.  What are the experiences of other riders with those connectors?  Are they recommended?  Recommended on the fuel feed line? TIA

[JamesInCA]

I've got the corresponding new return-side line sitting on the toolbox, but haven't replaced it yet because the access to the fuel pressure regulator seems like a not-so-fun job.

Tangential to your main question, I left this job sitting for a while for the very same reason. When I got around to it, turned out not to be much of a hassle at all. The air box stuff is pretty straightforward to remove and replace. Just a little fiddly.

While you're in there, replace the vacuum hose to the FPR, whether it needs it or not. No point in saving $2 on hose just to have to go in and take it all apart again. (The 3/16" vac hose from NAPA works great.)

[mac]

I have been considering those "quick disconnect" things.  The fuel line is very short though, and that make me wonder if it would be practical for this application.  What are the experiences of other riders with those connectors?  Are they recommended?  Recommended on the fuel feed line? TIA

I was thinking about these as well. Asked around last year. Responses were mixed.

[Scott_]

Back to the OP about smelling fumes.
IF your bike has been modified with the "AIR ACCUMULATOR CUP" you most likely are smelling the vapors from the vent that is OPEN to the atmosphere.

The California emissions requirements originally had the tank vent tube(vac hose) routed down to a block mounted vac fitting. It sets down on the top of the engine block in the middle behind the radiator. The intended design was the the internal of the block was supposed to be in a "negative", or vacuum, condition so they piped the fuel tank vent line to the block with the intention of "recovering" the fuel fumes and burning them thru the TB vac intake connections.
Just like the fuel evaporation setup on today's cars/trucks.
One drawback of the BMW design was that if you over filled the fuel tank the excess fuel would get sucked down the line and end up in the motor oil.

I have the "cup" modification on both of my bikes and from time to time if I overfill the gas tank(worse on a warm day) not only will I smell gas, I'll see it drip on the ground from the overflow line.

[johnny]

my motoheaps always smell like gasoline... i took the flapper out... so i gotts to put it on the center stand with a full tank or gasoline will drip from my overflow hose by my right peg... furthermore... since im consistently leaning till the pegs scrap im often getting gasoline in my overflow tube as a result... if it aints dripping i aints pushing the edge of no return...

j o

[Grim]

Another quick fix for me and saved me a bunch of work.

Finding gas residue on the bottom edge of the right side of the tank leaking down the back of the battery cover. Figured the Sender O-Ring was leaking. Picked one up on the way home but decided the search the symptoms and found this thread. Found the hose near the peg and followed it up. Gave it a light pull while looking on top of the air box and sure enough the vent hoses was not connected to the tank.  Was able to lift the tank enough to reconnect it. See how that does for the next few days.

Thanks again.

[Scott_]

Be careful which hose you connect to which nipple.

One nipple goes to the tank inter vent, this nipple was intended to be routed back to the crankcase. The block fitting is on top of the block behind the middle of the radiator.

The other nipple on the underside there connects to the "rain drain". A little hole on the left side of the fill cap. You can only see it when the cap is open. The purpose of this is as the description says, drain rain water away from the fuel tank inlet. And of course its on the left side for when you have the bike on the center stand.

Just don't mix the hoses up. Or you will end up with gas on the ground and water in the engine oil.  :yow

[Grim]

Well thats sort of important Do your know what one is the vent?

The one not connected on mine was to the rear. The front line was molded and clamped.

[Scott_]

Well thats sort of important Do your know what one is the vent?

The one not connected on mine was to the rear. The front line was molded and clamped.

Read this post from the Duck in the lieberry.
http://www.motobrick.com/index.php/topic,989.msg3961.html#msg3961