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Discussion Starter · #1 ·
Ok, so I've just started to "refurb" my new 97 xc440. When I first got it, last week, it started and ran fine. So it sat for a week with the fuel shut off in the on position. I go to start it today and put the choke in the first position, and give it a pull. It sparks right away and then dies. So i pull the plugs and check the spark, it has great spark. I notice that the plugs are wet, so its definitely getting fuel. So the engine acts like its flooded and i only pulled it over 5 or 6 times before i pulled the plugs. How can an engine be flooded that fast? So i let it sit for 15 mins and give it a shot again. Nothing happens still flooded. I do this several more times, all within an hour and a half. At this point i decided to move on and replace the front shock, so i pulled out the exhaust to access the shock tower, and the pipe is filled with gas, about 3 or 4 cups of it. What the hell? How can that much gas have made its way into the exhaust? Can gas flow into the engine from the carbs, even if the throttle is closed and the sled is off? I can't understand how the sled would have A.) been flooded so fast and B.) have that much gas in the exhaust. I wonder also if the crank case is full of gas as well. I didn't pull the drain plug in the bottom of the crank to check yet. I pulled the carbs apart to check for blockages in the main and pilot jets, but it looked clean. If you have any advice please help!

Thanks,
 

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x2 pull the case plugs and let here dry out. fuel will prob. run out of the case. You can still run it until you get the N/S in by making sure you turn the gas off.
 

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^^^^x4. Had same problem on the xc 500.
 

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My 700 did the same thing last year even AFTER i cleaned my carbs, so i took the carbs out again and cleaned them a second time REALLY good, never had a problem with it again, just shut the gas off when trailering
 

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Discussion Starter · #7 ·
Ok, so let me ask a dumb question. Does the needle sit in the main jet when the throttle is off? I don't understand how gas could go from the tank, into the carb, and then down into the engine if there is no fuel line pressure. I asked a fellow sledhead, at work, to see if he thought that made sense. He said no, because you can change the position of the needle by adjusting the c-clip stop which would raise or lower the needle depending on where its set. He thought that if the fuel pump had a bad membrane, since the gas tank sits higher than the pump, that the pressure of the gas in the fuel tank might be enough to push it through the bad membrane and into the crankcase via the vacuum line that runs the pump. Does that make any sense?
 

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Main jet and jet needle only come into play at open throttle...Your float and needles and seats are the culprit. They are located in the top of the bowl area.

The needle and seats tell the gas to come into the carb. The float then gets to a certain level and hits the N/S and shuts off the incoming fuel. Your problem is either wear or contamination has the needle and seats stuck open...Fuel continues to flow constantly unless the fuel is shut off manually with the valve.
 

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luhms01 said:
He thought that if the fuel pump had a bad membrane, since the gas tank sits higher than the pump, that the pressure of the gas in the fuel tank might be enough to push it through the bad membrane and into the crankcase via the vacuum line that runs the pump.

Remove the vaccume line from the block and place in a glass jar....if it fills with gas overnight he is right. Remember you have to have the gas shut off on.

5 bucks says its needles and seats(you will need to drain the crankcase again) .....N/S are the most common problem on these sleds.
 

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Discussion Starter · #10 ·
dodger said:
luhms01 said:
He thought that if the fuel pump had a bad membrane, since the gas tank sits higher than the pump, that the pressure of the gas in the fuel tank might be enough to push it through the bad membrane and into the crankcase via the vacuum line that runs the pump.

Remove the vaccume line from the block and place in a glass jar....if it fills with gas overnight he is right. Remember you have to have the gas shut off on.

5 bucks says its needles and seats(you will need to drain the crankcase again) .....N/S are the most common problem on these sleds.
That makes sense. I'll try the carb first, it seems unlikely that with only 4000 miles, the fuel pump would be bad.

So according to the parts list at polaris, i would be looking to replace item #24 the 3130046 VALVE ASM,NEEDLE Substituted by 3130643 (1.5)?


http://parts.polarisind.com/images/3787%5C3787C013.gif
 

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indys are notorious for flooding , always turn the gas off and you'll be fine if the carbs are clean the next time you go to ride it she'll fire up on the first or second pull.
 

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get the viton ones

http://www.hiperf.com/cgi-bin/sh000001.pl?REFPAGE=http%3a%2f%2fwww%2ehiperf%2ecom%2fcgi%2dbin%2fss000001%2epl%3fTB%3dA%26GB%3d%26SS%3dmikuni%26PR%3d%2d1%26PG%3d%26REFPAGE%3dhttp%253a%252f%252fwww%252ehiperf%252ecom%252facatalog%252f%26SHOP%3d%2520%26PN%3d6&WD=mikuni&SHOP=%20&PN=Snowmobile_Parts_Jets___Mikuni___Keihin_82%2ehtml%23a238_2d15SS#a238_2d15SS
 

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Also take a look at the bottom of the choke plungers. There are little rubber pads on the bottoms. Over time spring pressure holding the plungers shut will create a permanent indentation of the rubber sealing pad and will allow gas to siphon through into the carb throat. You may be able to remedy that problem by adding some preload to the plungers, but replacing the plunger is the real fix and not too pricey.
 
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