Fuel tank pressure

[dermothalcyon]

Ok, second K1100, had this '93 for 3000 miles, last couple times when opening the fuel filler cap, "POOOOF" outward blowage of air/fumes. Have not had the tank off since last fall, most of the last 20/30 fuel ups no issue, just last couple "whoosh". Thinking that the hose that vents into the crankcase is plugged.
Any ideas?

Thanks

[Laitch]

Sometimes fuel caps need to be overhauled. Here's what the kit contains. Here's Chris Harris's instructional video.

Before you do that, do the modification in the pdf at the link below. That stopped the huffing and puffing of my Brick's fuel cap. My tank still has the flapper baffle but if yours doesn't, this modification should help anyway. Without the baffle, fuel tanks can be too full to ventilate well when heated during travel or by hot weather, and the air blast when opening them could be inevitable. I didn't see the point in removing the baffle for a few fluid ounces of increased fuel capacity. There's plenty of fuel available in the USA for a traveler capable of planning. I'm not traveling long barren distances but if I were, I'd add filled Rotopacs to my kit.