How to Troubleshoot Starting Issues with Your FH721V-FS01S Engine?

It sounds like you're dealing with a frustrating situation where your new engine won't start. Since you've confirmed that the fuel control solenoid is opening and you have good spark, it seems like the issue might be related to fuel or the air-fuel mixture. A good first step is to spray some carb cleaner into the carburetor. This can help loosen any dirt or corrosion that might be causing problems, even if the engine is new. It's also worth checking if there’s any history of fuel pump replacement. Sometimes, a failing fuel pump can cut off fuel supply unexpectedly, which would prevent the engine from running properly. Additionally, inspect the vacuum hoses. If any of them are disconnected or worn out, that could lead to issues with the engine starting. If you've gone through these checks and everything seems fine, it might be time to consider the carburetor itself. Internal components can fail, and if you're comfortable with it, you could look into rebuilding it or replacing it with a repair kit. If you’ve checked all these areas and the engine still isn’t starting, it might indicate a more serious issue, like low compression. You can check this by turning the engine over manually; if it turns easily without resistance, that could confirm your suspicion of low compression. In that case, you may need to think about rebuilding the engine. Hopefully, these suggestions help you get to the bottom of the issue!