Gas cap hiss

[smordue1]

Anybody notice a hissing coming from their gas cap? Just started. I can release the pressure by opening it, but when I close it the hissing comes back. Thinking cap may be defective.

 

[Mighty Mouse]

The hissing taking the cap off of course is normal but the hissing with the cap going back on doesn't sound right. It does indeed sound like a defective cap. Maybe check for the infamous tank snake since you do live in Florida.

 

[Gregger]

On the older Rockets the tank vents through a rubber line that ends up behind the engine around the swing arm pivot. I'm guessing yours has one also (just not sure where) since the tank has to vent. I wonder if yours is pinched? Also, your bike might be equipped with an EVAP (Evaporative Emission Control) gas canister. If so, gasoline vapors would vent to this and later be pulled back into the engine to be burned... an emission control device. Don't know if these have them, but being Euro 5 compliant one would imagine.

 

[TURBO200R4]

On the older Rockets the tank vents through a rubber line that ends up behind the engine around the swing arm pivot. I'm guessing yours has one also (just not sure where) since the tank has to vent. I wonder if yours is pinched? Also, your bike might be equipped with an EVAP (Evaporative Emission Control) gas canister. If so, gasoline vapors would vent to this and later be pulled back into the engine to be burned... an emission control device. Don't know if these have them, but being Euro 5 compliant one would imagine.

I was hopping that someone with more experience than me would answer up.
but we can do what we can if they they dont answer up.

 

[nas6208]

Anybody notice a hissing coming from their gas cap? Just started. I can release the pressure by opening it, but when I close it the hissing comes back. Thinking cap may be defective.

Although most noticeable when air temperatures are warm, I can hear a periodic venting sound coming from what seems to be the gas cap. It is pretty quiet and can vary from every few seconds on a hot day with a full tank, to just every once in a while on cool/cold days with mid to low fuel levels. I thought the emissions vapor recovery equipment was supposed to route all the venting through the charcoal cannister, not out into the atmosphere. Maybe it is more of a pressure relief function than a venting one? Don't know...

 

[TURBO200R4]

Not much response so i will tell u all i know about the 2020 evap system.
Nothing lol

My working on cars/trucks with evap problems. The evap system usally has a pump that pressurizes the tank to between 1 to 3 psi most fail because of cap or rubber hose failure.
Some failures has coode of small leak and the next time will code of gross leak.
Some failures occur when the cap is dropped and that unseats the small spring and ball that allows air to enter tank.
I would assume if the leak was to much it would set a code which will not affect running but if the check engine lite is on u will never know if u have a greater prob so i would reccomend fixing the prob.
ON CARS
AS a general rule the ecu checks the evap system when the gas gauge is between 5/8 and 3/4 full and when u r going around 55 mph.
Most cars nowdays the ecu
Has what they call drive cycles
For example start car let idle for 5 minutes then drive 35 for 5 minutes then drive at 55 for 5 minutes. Then let off gas and coast to almost stop before stepping on brakes. This is one drive and some times u have to do this twice to get the ecu to complete all tests.
Then it will pass emmsion testing.
Anybody interested can look for the evap valve/pump / purge on wiring diagrams or in componets. 2020
Long story short i think u have a bad cap if that is the hissing componet. LOL

 

[CrzystghndKC]

That all sounds like stuff to get rid of. I hate new restricted stuff.

 

[TURBO200R4]

That all sounds like stuff to get rid of. I hate new restricted stuff.

It is meant to control gas fumes from venting to atmaspear.
Personaly i think that the making and maintaining this system will waste more fuel than it saves
But that is another story.

 

[Zutt]

I also hear a sound coming out of the gas cap. Once I unscrew the cap and remove it, sound goes away as if all the pressure is released, and shortly after screwing it on, it comes back. Exactly like the OP describes. Not much of a hissing sound, I just don't know how to describe it, but it sounds like air or vapor is slowly finding its way out.

 

[smordue1]

I also hear a sound coming out of the gas cap. Once I unscrew the cap and remove it, sound goes away as if all the pressure is released, and shortly after screwing it on, it comes back. Exactly like the OP describes. Not much of a hissing sound, I just don't know how to describe it, but it sounds like air or vapor is slowly finding its way out.

Does not seem right to me either