SAFETY CONCERN ?? 2017 G4-850 Fuel tank pressurized

[julians]

Was out riding this weekend and took a break pointed slightly down hill. After a few minutes I started smelling gas and saw fuel pouring out of one of the holes above my left side shock (vent hole?).

I turned the sled up hill and it stopped then I released the pressure from the tank. I took a run up the the hill and when I got back to the bottom I opened my gas cap and the tank was pressurized again.

Is this normal?



.

 

[Motodrew]

I've noticed sitting down on the seat applies pressure to the fuel tank. This constant repetition of sitting up/down likely is the reason for pressure buildup.

 

[turboless terry]

My wife's sled did the exact same thing one day. Turned it sideways and released cap and it quit. Haven't had mine do it.

 

[towerrigger]

Same deal here. I took the valve out of the tank to inspect it. It allows air to come in but not out. It is the same green rubber valve they use in the oil cap. Every time I stop now I unscrew the cap and let the pressure out.

 

[NWaxys]

I've filled mine up after a ride before and forgot that it's under pressure the cap blew clean off and up in the air as i unscrewed it

 

[BIG C]

Mine was doing same thing for the first time yesterday in wolf creek pass, it was hot out so I don't know if that had something to do with it.

 

[b-litt]

The vent that is on the clutch side above the shock has always leaked on the XM and 850 from what I've seen. It only does it when it's sitting on a steep pitch pointing down. My XM seemed to do it worse though. You could watch it pour out. My 850 is more of a drip. The 850 is the first sled that I've noticed the cap flying off from pressure. Mine does it too....

 

[julians]

Thanks for the replies. I hadn't noticed it before so I wasn't sure if I needed to get it checked out. I was in the 50's so that may have had something to do with it.

 

[PaulAnd]

My 850 smells like raw fuel alot.. usually facing downhill, Lots of pressure in the fuel tank even when not sitting on it..
I find myself unscrewing the fuel cap everytime I stop subconciously.?.
Did it facing uphill 1 time...
DOH!!!!!!
My XM did it also just not as bad

 

[Evanbcx]

Anytime I take off my cap and not holding on to it tight it shoots out of my hands into the air

 

[HFH]

I had the same thing happen to two different sleds a couple weeks ago. We were at 12,000 ft and it was warm. My 2016 Arctic Cat m8000 would not start after taking a break. I tried taking the cap off and it didn't really make a difference. We had to pull the cord for about 40 min. While all this was happening we looked and gas was pouring from the left front of my 2017 summit 850. It dumped a lot of fuel. We let it sit, and tried to take off the gas cap. It was a geyser, i had it practically lift my hand in the air. I had to quickly screw it back on. I had to crack the cap till it leaked for about 30 minutes. We finally moved it off the pool of gas and it started and ran fine. The M8000 finally started as well, but it took tons of pulls, the skidoo had e-start. It was really warm and high altitude. We went to a lower altitude and bothh sleds were normal. We had two other arctic cats that ran fine and never had a problem.

 

[off trail mike]

Fuel Vapor Pressure guys!

Same problem if you take a 5 gallon gas can from outdoors and bring it into your heated garage. The gasoline heats up which drives up the fuel vapor pressure and the gas can swells.

Most sleds have a valve in the tank to relieve the pressure either way (too high or too low)

You gotta keep in mind that the gasoline in your tank goes through some huge temperature cycles...remember the fuel cooled ECU in your 800/850 etec?? That heat goes into the fuel tank!

Bottom line is be very careful when removing gas cap and remember the tank valve will vent air or fuel depending on fuel level in the tank.

I always leave my gas cap loose when bringing my sled indoors to ensure it doesn't leak fuel on the floor via the overflow.

Normal

OTM

 

[black z]

Reid vapor pressure. RVP

 

[FearMyWrX]

Interesting, my RMK Pro used to smell of raw fuel a lot, could never figure it out or find a leak anywhere. I never tried unscrewing the fuel cap.

 

[mountainhorse]

If the factory venting system is not allowing vapor pressure to vent... then there is something wrong with the system IMO....

The Tank 'check valve" (#60 in the photos, AKA 'combination valve') should also have a pressure 'blow off' feature that allows excess fuel vapor pressure to vent off. There is no EVAP control device requirement on sleds to the best of my knowledge.

A friend of mine bought 3 new G4 Sleds this year... I worked on them a bit... had them in my shop with the heat turned up to 80˚F for paint to dry.... I unscrewed the cap.. and no excess pressure on any of them and they all had varying levels of fuel..... which leads me to believe that the Check Valve is malfunctioning in some sleds.

.

 

[Dazzler]

Fuel Vapor Pressure guys!

Same problem if you take a 5 gallon gas can from outdoors and bring it into your heated garage. The gasoline heats up which drives up the fuel vapor pressure and the gas can swells.

Most sleds have a valve in the tank to relieve the pressure either way (too high or too low)

You gotta keep in mind that the gasoline in your tank goes through some huge temperature cycles...remember the fuel cooled ECU in your 800/850 etec?? That heat goes into the fuel tank!

Bottom line is be very careful when removing gas cap and remember the tank valve will vent air or fuel depending on fuel level in the tank.

I always leave my gas cap loose when bringing my sled indoors to ensure it doesn't leak fuel on the floor via the overflow.

Normal

OTM

I have never had that issue with a any of the Polaris or Yamahas I've owned to date, I would think that a pressured up fuel tank that will blow the fuel cap out of your hands while removing has a venting issue and would be considerably unsafe??

 

[paulharris]

its not normal. i have never had any sled blow the gas cap off. the gas can analogy is not the same because the gas can can does not have fuel lines drawing from it like a sled does.

 

[Snowmixer]

I would also think that the changes in elevation between where the gas tank was filled and going up to higher areas could add to the pressure in the tank. Just like when you bring a bag of chips from home/lower elevation up into the mountains and it almost pops. It still seems like the vent should allow the pressure to escape before getting to the point of blowing caps out of hands, but I have no idea what pressure a relief valve/vent should be venting at.

 

[stmike]

There should be no pressure in the tank,i would be getting the dealer to get to the bottom of the problem .

 

[off trail mike]

Not trying to defend BRP, but I'm pretty sure the 2 way valve is there to protect from fuel spills and venting fuel vapor when the sleds are on their sides or inverted or climbing a steep chute or rapidly changing elevation. My old yami Nytro has a "U" pipe which constantly vents the tank but can also spill a bit of gas when you flip it back on the track from a roll on the side with a full tank. I for one can live with a bit of tank pressure over gasoline sloshing about inside the engine compartment (or exterior of sled) with a 1000 deg. muffler in there.

Because those valves are probably 2 way, you need some pressure difference (deadband) for the valve to function in the first place. It can't be much pressure because you'd wreck the tank if the pressure got to too high (split) or too low (collapse)

I've also seen air rushing into the tank if you take sled from the garage to outside on a cold day but it never seems to be very much, although very hard to tell.

Seems to me it would be pretty easy to test how well the valve operates if there are doubts. They use Nitrogen to test safety valves on pressurized hydraulic tanks. This would be similar. I'll bet BRP has a tool or procedure for that!

OTM