I have twin 2003 225 fichts which will shut down after running for about 20 minutes. I then have to wait about 15 minutes before they will restart. I seem to smell gas when they shut off. Once restarted they will run another 15-20 minutes before shutting down again. This goes on all day. No warning lights and guages show ok. Batteries seem ok just motors will not crank until waiting period over. Anyone have a clue what is wrong?