Got a JD X300 that will crank and run 5 minutes at a time then cuts out and stalls. Gone through carb, looks good, pumps fuel fine, filter open...out if ideas.
Is there a fuel supply shut off valve? If so, remove the hose from the carburetor, hold it over a container to catch the gas, then check the flow of fuel when you open it. Then check the flow of fuel when its positioned halfway between the on and off positions - it may flow more freely in that position.
I recently fought a generator for 2 weeks because it acted like it wasn't getting enough fuel. It had much the same problem as your x300 - it would run just great for the first few minutes, then the engine would start surging. All my trouble shooting pointed to a fuel supply problem. I ended up cleaning the carb twice, adjusting the governor, slopping gasket goop all over the carb and intake gaskets, dumping seafoam in it (even tho I'd already cleaned the carb), completely emptying and cleaning the gas tank and hose that fed the carb, and cleaning the fuel supply valve. NOTHING worked.
Then I decided to check the flow of fuel into the carb. When I turned the supply valve to the "full on" position, fuel was barely dripping out - but when I slowly started turning the valve back towards "off," I noticed that about halfway between on and off, the fuel flow was "generous" so to speak. I hooked the hose back up to the carb, turned the supply valve to halfway, started it up and haven't had any trouble with it since. I don't know why, but for some reason, the fuel flowed better at the halfway open position than it did in the full on position.
