Engine is used for trolling and it was running great and then it seemed like it needed more throttle which I gave it. After about 10 more minutes it just quit and won't restart. I have fuel to the carburetor and in the bowl. Float shuts off fuel and lets it fill the bowl. I have spark at the plugs. Tank vent is open. Tank is full of Non-Ethylene Premium. Air intake screen is clear/clean.