650/X-2 750 sx wont run, blowing fuel through motor

Main problem- When turning motor over with plugs in, as soon as i crack the throttle, the starter stops turning. This happens with a freshly charged battery, and with jumper cables attached to a car battery. When i take the plugs out the ski is pushing fuel through the spark plug holes like crazy. And it is coming straight from the tank. Somehow the carb is just dumping fuel! I thought it was flooded, so i was trying to clear the cylinders and before i knew it i had ran 1/3 tank (650 X2 tank ) of gas through the motor in the driveway, just pushing the fuel out the plug holes, by spinning the motor over for approximately 3-4 minutes.

This motor is swapped into an 86 kaw X2. i had the motor running fine, then i closed the hood and pulled the front spark plug wire out from the boot. I re routed the plug wire and now it doing what i mentioned above.

the motor has strong spark in both cylinders, and i have not changed the fuel lines since it was running just fine. Top fuel line from carb going to return, bottom fuel line is the supply from the fuel/reserve switch.

any suggestions would be great so i can get this ski onto the water
 

OCD Solutions

Original, Clean and Dependable Solutions
Location
Rentz, GA
Crack the cap on the fuel tank and note how much pressure escapes. I had a ski that would pressurize the gas tank to the point that it would pop the needle and seat and fill the cases with fuel.
 
Crack the cap on the fuel tank and note how much pressure escapes. I had a ski that would pressurize the gas tank to the point that it would pop the needle and seat and fill the cases with fuel.

I have a buddys roundnose that does the same thing ever since putting a billet fill cap on. Leads me to believe it must seal better. Did you ever find a fix for this? If left after riding with the fill cap tight (stock external fill) it will flood the engine.
 

OCD Solutions

Original, Clean and Dependable Solutions
Location
Rentz, GA
I installed a fuel shut off valve on mine to resolve it although I can't remember the last time I ever shut it off.
 
Thanks for the suggestions guys. i will give the fuel cap a shot. I was thinking that the return line inside the carb was plugged so i pulled the carb and let it soak for a week in solution. also trying to get the gas out of the ski, it caught fire and i got some 2nd degree burns. I took the plugs out of the wires, but i should have hung the wires out side the ski. I didint and i guess one of them arced to the block and ignited the fuel i had been getting out of the motor. I am waiting for my arm to heal back up then i will give it another shot lol.

OCD- you mounted a fuel shutoff valve on the supply line? i dont understand how that would help, because you would have to have the valve open to ride the ski, and the only difference would be it is flowing through an open valve. Could you explain?
 
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Check your carb... sounds like the needle may be stuck open and probably some loose wiring causing it to shut the starter down but the throttle shouldn't be the trigger for it to shut down except it runs through the same wiring harness as the starter switch down the stearing stem so maybe when you hit the throttle since it moves a bit could be shorting out a loose wire. Check your grounds directly in front of the stearing stem on the CDIG and theres a wire that comes from the negative battery cable that grounds to the engine you should check it make sure you did that when you swapped the engine. The starter though shouldn't be your flood problem like i said it could be the needle stuck or you mixed up a line but from what you wrote those 2 are correct for sure but there are a lot more than 2 lines running your fuel system. If i had more info about what you did when you swapped the motor over it would help. Did you take the carb apart at all... are you using the carb from the 650 or 750... the 750 would run more fuel and your using the 650 tank so what else are you using from the 650?
 

OCD Solutions

Original, Clean and Dependable Solutions
Location
Rentz, GA
OCD- you mounted a fuel shutoff valve on the supply line? i dont understand how that would help, because you would have to have the valve open to ride the ski, and the only difference would be it is flowing through an open valve. Could you explain?

The problem I described happened between rides on really hot days and during storage, I just never noticed until I was going to ride the ski again. Once the tank pressurizes, all it takes is a bump to unseat the needle and the fuel will begin to flow. Once unseated, the needle will not reseat until the pressure is equalized. I would bet that that the flow would have stopped for you had you cracked the fuel cap.

The first time it happened to me, I had finished riding with 3/4 tank of fuel left in the ski. When I got home and was cleaning it up, I noticed the hull had about an inch of fuel in it and the tank was almost empty. It wouldn't turn over so I pulled the plugs and fuel shot out of the holes.
 
86x2- i had not taken apart the carb, and i swapped the complete motor, carb, and cdi/ ignition box out of the 750ss. Everything is 750 electronics except the bilge pump. i am going to put the carb on soon, hopefully tomorrow and i will see what happens

i appreciate the reply s guys
 
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