This may have been addressed in a previous post, but I could not find it. If so I apologize.
I have a 616 with a 16 hp B&S Vanguard engine.
After mowing for the amount of time it takes to use about a half of a tank of gas the engine stops. It doesn't spit or sputter, it just quits with no warning. If it sets for 2 or 3 minutes it will crank and run for a few minutes and then shutdown again.
I have replaced the fuel line from the tank to the carb. Replaced the fuel filter. Replaced the fuel pump and replaced the hose from the fuel pump to the cam. I replaced the fuel cap and I also replaced the air filter. The fuel is fresh. The oil is nice and clear. I have mowed several times already this year and filled it up each time with new gas. This started about 2 weeks ago.
Can anyone suggest what else I might try to fix this problem?
I'm not one of the mechanical experts here but it sounds to me like you may have an issue with your coil. They will sometimes operate fine when cold and then fail when a critical temperature is reached. That temperature would take a while to be reached at first and then be subsequently reached more quickly after a short rest.
I'm not able to help you diagnose if the coil is indeed your issue. Perhaps one of the experts here could help with that?
grab a can of carb cleaner or starter spray.
The instant the mower stops give it a quick squirt down the carb.
If the engine fires right up & you can keep it running for 30 seconds or more by repeated shots of fluid then you have a fuel problem.
Next simple test is to remove the fuel cap and blow back up the fuel line into the tank.
problem goes away for a while = debris blocking off the fuel outlet.
To check the electrics, get a pair of red in line spark testers and fit them to your mower then go mow.
When the mower stops check to see if they are flashing.
No flash = electrical problem.
We need to work out which system is causing the shut down