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i'm wondering if anyone can tell me why I am blowing feul pumps. I have owned the sled for 4 years and have done a feul pump every year since. I haven't put on alot of miles but shouldn,t have any problems. It is a 1995 skidoo mach 1 670. i had it started this year and went for a ride. i stopped after about an hour to check my cluth bolt because i had them rebuilt last year. I shut it off and it wouldn't start again. I took it home and found that the feul pump had gone, and the outer crank seal was shot. fixed them both and put it back together. started it up adn it ran for 2 minutes and then blew the feul pump again. I don't know why and could use some help. i don't alot about skidoos but i am a car mechanic, so i know a little bit. The other thing i forgot yo mention was that i had to change the feul pump because the one is obsolete. i put a mikuni on it from my local dealer. the inlet on the old pump is 3/8 line and the new one is 1/4 line. the carbs i have are 44's.

thank you
 

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CHECK THE PULSE LINE COMING OUT OF THE MOTOR TO THE FULE PUMP. IF IT HAS A LARGE AMOUNT OF GAS IN IT OR IF IT IS CRACKED IT COULD AFFECT YOUR PUMP. ALSO IF ANY WATTER IS IN GAS IT WILL FREEZE AND CRACK THE DIAPHRAM. YOU DONT NEED TO BUY A NEW PUMP THEY SELL REBUILD KITS ALSO. HOPE THIS HELPS. CARLSON RACING
 

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When you lose the fuel pump I assume you are blowing the diaphram? Maybe fuel or water contaminents making their way to the pump. Also wondering if the pulse line is putting out too much. Don't know if blow by on the rings may cause this. How are the rings?
 

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Hot foriegn materials getting in the pulse hose is usually the culprit for this you may want to check blowby or crankbearing cages.
 

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Sounds like you are building up too much pressure in the crankcase - that would explain the crank seal problem coupled with the fuel pump problem.

You might want to do a compression test and then repeat with oil in the cylinders to verify the condition of the rings.
 
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