I have a quad runner that has been starting perfectly for montha and now it doesnt. The starter is clicking but it wont turn over. I tried pull starting it, i changed the spark plug and battery,
The air box had gas in it and im not sure if thats because of lifting the front end of the atv up or the carb. So i took the carb apart and cleaned the jets.

It started for about 20 seconds and when i let off the throttle it died and wouldnt restart

What else could it be?

 

Update: if i hold the throttled all the way it'll start but blow quite a bit of white smoke out of the exhaust and then die

 

Check if the oil level has risen, and if it smells of fuel. Your carb float may have stuck and filled the cylinder with fuel. If it has, empty the air box, clean the air filter and change the oil. Once running, it will clear any remaining fuel out but, if it has a prime position on the fuel tap, don't leave the tap on prime. You may need to fit a new float needle, but it could just have been a bit of grit, that has now gone.