My relative had the exact sled. It sucked. Always had a problem. Had a similar problem just like this one that your having. Found it to be cracked fuel lines coming from fuel pump. It wasn't just one line, it was a couple all at the same time. If this is the solution to your problem, change them all, fuel line isn't too expensive, and it would be bad if any of that fuel would start to squirt on your exhaust or motor.