most likely the fuel hoses are cracked or the primer bulb is cracked. start in the tank see if the inline filter has rotted off, then inspect the rest of the hoses.

They a check valve in carb. that close makes primary pump work if its destroy I've replaced Carburetor on my engines.

I would use it in my car ,IF, I could buy it

The PTO I refer is is how your deck blades are engaged/disengaged. If you have an electric PTO clutch you just flip (or pull) a switch on the dash to engage/disengage the blades. Having a manual PTO means you must physically operate some kind of large lever control to engage/disengage the blades. Because of the extra electrical load imposed by having the electric PTO clutch, a higher amp alternator, along with a higher amp fuse is required in tractors with that feature. Looking at this schematic, I see that a simple diode (without a regulator) is featured as a current rectfier.............that means low output charging system, hence the 15 amp fuse specification. I also see a PTO switch, but no electric PTO clutch. That means that THIS switch is a safety switch (part of safety interlock circuit) and functions only to kill the engine, or to inhibit the cranking motor, under certain conditions. And to re-state for the 1,000th (or so) time. The electric fuel solenoid on ANY outdoor power equipment is only there to help prevent the loud afterfire BANG! that can occur when shutting down the engine. The afterfire solenoid IS NOT tasked to shut off ALL fuel flowing INTO the carburetor. It is tasked only to shutting off the fuel flowing OUT of the carburetor MAIN JET. When the key switch is turned off, the fuel solenoid blocks only the carb main jet, and that is how it prevents the shut down bang blues. But, the carb pilot jet can still flow a little bit of fuel, and that is why it is recommended to also have (and use) a manual fuel shut off valve. The manual valve, if closed at all times except when the engine is running, will absolutely prevent you from ever having an engine get drowned with gasoline during storage. The afterfire solenoid cannot provide any protection against fuel drowning of the engine if a carb needle valve leaks during storage of the machine..........because it does not block the pilot jet. So if you did not know why an engine has a fuel solenoid valve, maybe now you do.