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Discussion Starter #1
So having owned and self serviced sleds all my life, I consider myself pretty mechanically apt at diagnostics, but this one has me stumped. Our daughter has inherited our '92 EXT 550 that we've had since the 90's. Always been a great sled. Now recently, it floods itself out after a fill-up; and only after a fill-up. It will literally flood itself to death to the point where we have to shut off the fuel valve and let it gag under full throttle until it empties the bowls dry. Then run it hard for the next ten minutes without stopping or it'll doo it again. Then it's fine. Runs and idles perfectly. My first thought would be needle and seat, or float, but why only at fill-up. You would think that the pressure from the fuel pump at any fuel tank level would be way more that the gravitational force of a full tank. And like I said, once it's gone five miles it's fine. 10 gallons should have just as much gravitational pressure as the 10 1/2 that are in it when it leaves the gas station. I'm stumped with this one
 

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Doesn't make much sense. Does it do it at idle? Try running it with the cap off. If it doesn't flood, you have a tank vent issue.
 

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You have small “contaminants” in various locations along the fuel lines (and maybe in carbs needle/seat entry area) that is being unseated (and then moving about for a bit) making the needle and seat not work as it should.

Having to run bowls nearly dry, then turning on fuel and running for a few miles is telling me that a major rush (surge) of fuel through the lines is flushing away debris to allow needle/seat to once again work properly.

Was a member on here about 8-9 years ago with same issue on his daughters Puma(?)

That’s (fine, hard to detect sediment) what it turned out to be.
 

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Discussion Starter #4 (Edited)
Yes, it does it at idle. It initially starts and idles fine for a minute or so, then floods out and won't idle at all. Shut fuel off and pull with wot until it starts to fire and clean itself out. My '99 Skidoo had little screens in the fuel inlet on each carb. Maybe a small pre-carb filter on each line and then like twatermelon said, check the vent. The only question I have with the vent theory, is if it's plugged, wouldn't the tank eventually suck itself into a vacuum as the fuel is drained out, and then starve the engine?
 

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Vent may be partially/MOSTLY restricted, leading to pressure buildups when tank is initially at its fullest, and that 10 minutes of riding can (and will) drop fuel level quickly, as that part of nearly all tanks is the smallest (volume wise) and 1/2 gallon gone can add substantially to the “air space” within the top of the tank, lowering chances of (possibly) restricted breathing creating enough pressure as the volume has increased.
 

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Discussion Starter #6
New bit of info, I opened the hood and noticed that the oil jug is nearly empty. We put on about 100 miles after topping it off this weekend. My son's '00 Zr did the same miles and took the same amount of gas (about 2 tanks) and only used about 1/3 of a jug. I always sync the oil controller with the throttle, but dont know that much more about them. Could this be related?
 
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