Fuel cap not venting - SOLVED !

[maury]

I have soaked in vinegar, used very hot soapy water, carb cleaner and compressed air.
Vent is still not working (engine stops, loosen and hear air, bike starts/runs normal).

Where exactly is the vent hole?
Is this something to do with the rubber seal?

Thanksk

[NotSoLilCrippseys]

On my GL1100, there are 2 holes at the bottom of the cap. I'm pretty sure they vent air out the side, where the "ears" are.

Also, the ears are spring loaded in some fashion. I'm not entirely sure how the air gets past the rubber seal. Maybe the vents are behind (but above) the rubber seals?

I just "blew" into the two holes; air clearly came through and out the sides.

You might source another cap on the *Bay. Maybe $10 or so. Or drill a small hole or two right through the cap and make your own vent?

[redglbx]

When installed the “ears” get pulled down and I believe uncover vent holes to the outside through the 2 holes on the bottom that NotsoLil referenced above. If you have an air compressor you may want blow it out as it seems bugs, spiders in particular like to build things i there that plug the vents.

[maury]

So.....
I finally solved the mystery (to me) of the non venting fuel cap.
There are 2 tabs sticking out of the side of the fuel cap. When the the cap is placed onto the fuel tank and turned, the tabs engage with and slide along and slightly down a metal ledge under the lip of the fuel tank. This then opens the upper vents. The lower vent is easy and is the round hole on the bottom of the cap. I placed the pick over and under the 2 side tabs and thoroughly scraped the upper/lower chambers of the cap. Compressed air blew out crud and pieces of small very thin metal.
The mystery is where are the upper vent holes? There's what appears as a very narrow metal band running around the inside of the cap. The band sticks out slightly in 2 places from the edge (see red arrows). When I placed a carb cleaner tip into one of the spaces, the cleaner shot right back out. I put the pick into the space, pushed hard and wiggled around a bit. When I put the carb cleaner tip back in, this time the cleaner came out of the tabs on the sides. When I then placed a screw driver to hold the tab open, the cleaner shot out of the bottom vent hole.
Mystery solved! I then took a long test ride to confirm.

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[redglbx]

Good news Maury ! One other thing I should add on fuel cap technology is that when you install the fuel cap the red paint dot needs to be facing forward in order to achieve maximum performance, having it face rearward will of course cause your bike to have sluggish performance,,, of course ! This has been a well documented performance technique!

[redglbx]

I should add that the above ^^^ is pure Wing BS ! But thanks for the pictures and great explanation of your experience ! I do believe that routine fuel cap maintenance is something that should be done. As I said above spiders and other critters like to build stuff in there that tends to plug the vents up, good job!

[Whiskerfish]

[Dirty Dave]

I find it confusing that when I release the gas cap there is a hiss
but I've never had a problem otherwise.

Went through the procedures mentioned above so will see if the hissing stops.

[Whiskerfish]

The hiss is pressure escaping. If pay close attention you will feel the cap get lighter in your hand as it is loosened as the pressure inside the tank tries to push the cap up. To me that means it is working as it should.

[robin1731]

The hiss is pressure escaping. If pay close attention you will feel the cap get lighter in your hand as it is loosened as the pressure inside the tank tries to push the cap up. To me that means it is working as it should.

This^^^^^^^

The vent is one way. It lets air in, not out.

[Dirty Dave]

Well I'll be jiggered!

Now I know.

[robin1731]

Well I'll be jiggered!

Now I know.

Gets really bad on a hot day. I've had the cap jump off when I loosened it before. You tend to expect it after the first couple of times.