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Discussion Starter #1
Ok, so my buddy bought my old 800 a few years back and wanted to ride on Sunday.
He put in fresh gas and plugs. It started after the third pull, and then died. Restarted it, ran for five minutes, and he shut it down. Went out an hour later, it would not start.

He gave me a call, and I went over and checked it out. Checked for spark, that was fine, put some fresh gas into the cylinders and nothing, Tried a bit of starting fluid, nothing.

So, it has spark and compression. Added some fuel, not even a sputter...... no back fire, nothing.
Key on, fuel on, shut off button up.....

Any ideas on what to check next???
Advice is greatly aprreciated
 

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Try cleaning the carburetors. Should be cleaned every preseason. Also check the line inside the gas tank to make sure it hasn't died off, replace the fuel filter as well. Replace any lines that look "suspicious"
 

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Discussion Starter #3
Thanks for the response, went out this morning, and the cylinders were full of fuel ;-)
Not hydro locked, but when I removed the plugs, it sprayed fuel every where
I am guessing fuel pump? I think the pump is three seasons old. Will pull off the exhaust and pull the drain plugs later today. I guess I should clean his carbs...... not really excited about that.
 

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Not only can a fuel pump cause that but also needle/seats as well if they have junk in them. Most likely it is the carburetor needle/seats. I have had that happen to me a couple of times only the needle/seats went bad. And yes clean those carburetors almost guarantee what happened was when it was ran after sitting for so long a piece of something got into the carburetor and then it couldn't flow. I am going to clean both sets of my two snowmobiles next weekend because of this even though I cleaned them last December and even though I only ran it twice during that time...I will end up with something in the carburetors. Best to take a couple hours always before running any snowmobile regardless if they say "oh I just had it out and cleaned the carburetors before that" been told that a couple times and laughed when I pulled the carburetors apart, both times they were full of nasty green garbage!

Try that first, also there should be a couple of plugs that you that you remove from the bottom of the block in front that will allow the gas to evaporate over 3-4 days. It takes that long when it is full of gasoline like that. Try that first then go to the fuel pump.

Good luck!
 

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Discussion Starter #5
Thanks for the feed back
Pulled both plugs and drained the crankcase. Also pulled the vacuum line on the fuel pump, and it was not full/
Was surprised to see both drains full of fuel.
Pulled the carbs, and the look decent, got the floats out and cleaned jets and the carbs well. Checked the needle and blew through them, and they seem fine with open and closed position.

If it's the fuel pump, would both sides be full of fuel?
Also, if it's the carbs, then would both sides fill up if when only one carb is bad? What are the chances both carbs had the same needle and seat issue?

Thanks for the help
 

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The only way it could be the fuel pump is if it is leaking through the pulse line, which you said is dry.

The carbs are the on/off for fuel delivery. I think I'd just replace the needle and seats just to be sure. Cheap and easy fix. Verify float levels.
Also, make sure the choke plungers (enrichers) are fully seating.
 

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Make sure you let that crankcase sit for a few days so all the gas is evaporated can't just drain it and then throw the plugs back in. As there will still be leftover gas in there for a couple days. Gas takes time to evaporate it isn't instantaneous.

Also agreed I would change the needle/seats as over time they can go bad.
 

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Discussion Starter #8
Ok, should we leave the drains plugs out?
Where is a good source or number for needle and seats? Looked at the Polaris online parts, looks like they sell it with a set with floats?
 

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When I have had that issue, I would just pull the plugs out and with the ignition off, pull the rope with the throttle wide open and the fuel shut off. When you can no longer see visible gas fumes coming out the plug holes, you should be ok. Do this outdoors and wait a few minutes to put the plugs back in before starting.

Having a fire extinguisher handy is not a bad idea, either... (trained professional :D )
 

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You can get those in a carburetor kit online. Mikuni or Keihan sells them all over the place.

And yes leave the plugs out if it was filled that much it will take around 2-3 days for it to evaporate properly.

Hence why let it evaporate Dan,lol. Ex FF/EMT here!
 

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Discussion Starter #11
Ok, cool. It looks like the float, needle and seat is one piece? The white "seat" has a o-ring that fits into the carb body and the needle goes inside the seat attached to the float. It looks like polaris part #3131231 at $100 each?
 

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I wouldn't pay that for any needle/seat. Those should be separate lemme go look.

What year, model and all that?

After looking at a used one on eBay the needle/seat can be removed without the float. You have to remove the float in order to remove the needle/seat. You remove the two bolts to do it.

And also after looking someone is claiming Ski-Doo uses the same float/needle/seat setup. As they are a Mikuni Flat Side Carburetor.
 

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Discussion Starter #13
this is on a 2000 800RMK

I can pull the needle with the "clip" but the plastic seat is part of the float.

Found this on ebay

sounds like the same as a Ski Doo............
 

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Okay after looking at Mikunipower.com and reading their 2012 product catalog they are out there. Is this a 40mm Mikuni that is on that 800?
 

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Why wouldn't it work?

That break down shows the correct needle/seat for all Mikuni TM40mm carburetors. They didn't exactly change them.
 

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This one says Mikuni the other says 2Fastmoto parts but I would buy the actual Mikuni for a TM40mm


Also the carburetor rebuild kit is a KHS-001 and they sell the needle/seat in it as well

And no 51 bucks isn't a bad price

 

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Discussion Starter #20
the plastic float assembly has the "needle" inside the plastic seat. I bet the needle would work, but not sure how to put the metal seat in the plastic float ......
65339
 
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