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2017 Grizzly. Last time I stopped at a fuel station along the trail, my fuel cap released pressure as if it was a radiator. I loosened it a bit further and it blew off, spewing fuel into the air into my face and onto my clothes. It sprayed out of there for about 10 seconds. A witness from across the parking lot who was also on an ATV came over and said he'd never seen anything like that before. He asked if my vent hose might be plugged. This could happen from riding through deep mud as mud would clog the end of the hose. I avoid mud when I ride so the deepest mud I would have been through is a couple inches. I ride hard and fast, corner and drift, and technical stuff. No mud. I looked under the seat where the vent hose is and followed it down to where it exits behind the rear trunk space. There was no blockage there. Why did this happen and what can I do to prevent it?
 

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Maybe the hose was bent somewhere along the way?

I‘d like to avoid mud as well but I am unconsciously attracted to every single puddle like a small kid! Just need to hit all of them!


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It does it because these bikes are notorious for building pressure in gas tanks and causing problems like the one you experienced.

Yamaha moved the tank in years 17-18 I think but apparently it’s still an issue. Some have tried installing heat shielding on the bottoms of their tanks, plastics, etc.

Mine always sounds like the gas is boiling and even if it’s 7 degrees out the fan comes on. They always run hot, not sure Yamaha has a fix or if there even is one.
 

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My buddy just had the same issue with his brand new 18. Sprayed fuel all over his new concrete driveway. Took it back to the dealer, they blamed all the insulation for retaining engine heat to keep it from the rider. They removed the rollover valve and replaced it with an inline fuel filter.......problem solved. The next week we drove down to Hatfield McCoy and went through several tanks of fuel. Hasn't had an issue since.
 

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Those rollover valves have been a nightmare to any vehicle they've been fitted to & there are lots of ways they can fail, simply riding over a lot of bumps can force the valve to seal & pressurize the tank, having exhaust systems crammed into every nook & cranny & curling around the gas tank to keep things compact won't help, replace it as suggested. If it happens on the trail etc, forcefully blow thru it both ways to try & clear it or bypass it to get you home, make sure it's replaced before you ride it again!
 
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Discussion Starter #7
Those rollover valves have been a nightmare to any vehicle they've been fitted to & there are lots of ways they can fail, simply riding over a lot of bumps can force the valve to seal & pressurize the tank, having exhaust systems crammed into every nook & cranny & curling around the gas tank to keep things compact won't help, replace it as suggested. If it happens on the trail etc, forcefully blow thru it both ways to try & clear it or bypass it to get you home, make sure it's replaced before you ride it again!
This was a very very bumpy ride.
What should I replace the valve with and which part is it?
 

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kdt1970 was on it, it's p/n 9 in the pic, also take note of hoses p/n 7 & 12 follow both of these & check for crimps, that their not squashed by plastic covers & that there not going to be squashed by covers when you put the seat back on, this is a nasty trick the bike can pull on ya >:) seat on, problem, seat off, no problem.
 
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It is part #9 and I found that you can take it apart, pull out the small ball bearing and put it back together again.

The ball is there to plug the line in the event of a rollover.
 

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My 2017 does the same thing but will also die and not restart until cooled down. One tank gets below 1/2 on hot day the bike will die and not start. Removing the cap relieves a lot of pressure out of the tank. Fuel boiling inside for a few minutes until cooled down. Takes an hour for the machine to cool down enough to run again. I'll be checking valve and hoses for blockage next. Lower pressure in the tank will allow fuel to boil at a lower temp. I bet its 160 degrees in the take...or hotter. Design flaw from Yamaha.
 

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My buddy just had the same issue with his brand new 18. Sprayed fuel all over his new concrete driveway. Took it back to the dealer, they blamed all the insulation for retaining engine heat to keep it from the rider. They removed the rollover valve and replaced it with an inline fuel filter.......problem solved. The next week we drove down to Hatfield McCoy and went through several tanks of fuel. Hasn't had an issue since.
Do you happen to have a picture of how and where the dealer installed that fuel filter?
 

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Let me get in touch with him Woodsman. I never looked at it after he had it done so I’ll see if he can take a pic. We live 3 1/2 hours apart or I’d get you one myself.
 

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Cool deal thanks!
 

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Hey Camo15 did your friend ever send that pic to you?
 

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Here is a video of the roll over valve being tore apart and cleaned. Fast forward to 5:44 in the Video.

 
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