EZ-GO Gas model
 

I have an older EZ-GO with Robin 2cyl 4 stroke motor, It stopped running, and I found that the air filter box was full of oily gasoline, and crankcase oil also an oily gas mix. Changed oil, cleaned filter box, cleaned plugs. Ran sort of OK for about 10 minutes, then when warmed up, would not start. Will start when cooled off, but only run roughly for 5-10 minutes. And the air filter box is again full of the oily gas mix. Some how, it is sucking crankcase oil up into the carb. Can you help with any ideas on how this is, and how to fix it? Thanks!

Hi Peter,
The first thing i would check is the fuel pump, if the bellows are cracked and leaking, oil and gas would show up on top of engine.
If ok you need to do a compression test, you may have a cracked piston or broken rings

Regards
Frank