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Hello, after coming home from a ride , I shut down the (new to me .snow machine 2007 gtx SDI 600) and heard a noise for about 5 minutes. I pull the main fuse at the battery, I pulled both relays and the noise continued.

The noise almost sounded like the fuel lines were depressurizing. It finally stopped with a lowering rate of noise.

Can someone explain this noise to me. are the fuel lines depressurising. Is something wrong that needs fixing

Hoping for some help. Thanks in advance.
 

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Like a high pitch whining sound? Could be the gas tank vent not venting properly. Next time you ride open the gas cap and see if it hisses.

There should be a blue check valve up under the console above the clutches. Some tube on either end, one going to the gas tank, the other going to the left shock top mount area. That could be plugged or stuck. I just drilled a hole through mine and no more gas tank pressure.

Just something to look into.
 

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5 min is a long period for the pressure to equalize after raising yourself from the seat, but it could also be perfectly fine. I would perform a pressure/vacuum test on both vents to ensure they are operating correctly. In the picture below you can see the two vents that are being tested.

The one hooked up to the pump is holding a vacuum. This is just to show it has a one way check valve. Some have an arrow to indicate the direction of free flowing air which tells you the correction position during installation and the correct testing procedure. The important test on this particular valve is when pressure is applied and it should show zero psi on the gauge. In other words it should allow air to escape with minimal resistance. This is the vent that allows the tank to breath in air as the level of fuel drops. If this check valve did not work then as the fuel pump would draw fuel it would cause a negative pressure (vacuum) in the gas tank that would make it increasingly difficult to draw fuel. It is also the valve that allows air to be drawn in the tank when getting up from a seating position and the squished tank takes back its form. I would want to ensure this vent works perfectly well since a faulty valve could lean and kill an engine. If the test is good then it means the sound it makes for 5 min is due to the time it is taking for the gas tank to take its form and that would be ok.

The other check valve - the blue on in the picture - is to allow air to escape the gas tank. This is the pressure that is created by the gas in the tank when it releases its vapours (light ends). It is the same pressure that is caused when shaking a gas can or leaving it out in the hot sun. On your sled the valves could look different, but their purpose and how they function is the same on all sleds.

Ooops, I almost forgot the picture.

Gas Tank Vents being tested IMG_1747.jpg
 

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Just drill the blue thing thru with a small drill,,no more horn noise or pressure buildup in the gas tank
 

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Thanks, I will check this out .

Hello Everyone, I went out and tried to simulate the same noise. Finally after coming home, I shut the machine down and there was the noise. I opened the gas cap and I could hear the pressure relieving from here and at the same time the noise stopped instantly.

I think you guys have nailed it and thanks. So do I drill out the valve , replace it , or it is working fine and leave it alone?

Thanks for the picture, it really helps.

Thanks again...
 

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You have a few choices:

1. Drill out the valve as DOO_TINT suggested and create a loop with a length of hose.

2. Remove the valve altogether and create a loop with a length of hose.

3. Test and possibly replace the faulty valve.

I can't tell you what is the best choice other than giving the reasons why I would want to keep a functioning vent system. During the riding and storage season I want the minimum amount of air in the tank, and the minimum amount of air flowing in and out of the gas tank. Air holds moisture so I want the tank filled as often as possible. Whatever moisture is turned to water will ether be absorbed by the Ethanol or alcohol added to non Ethanol fuel. Air also oxidizes everything around it from our skin to the plastic fuel lines and gasoline in our tanks. This is why we shrink wrap (vacuum wrap) our foods for long term storage. I keep all my gas tanks full for the same reason.
 

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That is a max tank pressure relief valve to keep the plastic gas tank from rupture and really only for emmissions of gas fumes

You dont need it and no worries about moisture,,03 and older sleds never had them
 

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It is the seat sucking air back into it, after you probably just got off of it. I had that squeaky noise till I found out what it was.

Sent from my iPhone using Tapatalk
 
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