Have a Yamaha 150 4 stroke which starts and runs great when cold. However, after running for around an hour or more, and when hot, it is very difficult to re-start. It cranks, but does not fire. If you let it sit, and cool down, then it re-starts again just fine. Have tried different gas, checked fuel filter, water separator and battery/connections. Will try using a separate gas tank to see if this solves problem. <br /><br />Anyone else have this problem? Any ideas on what might cause it? Thanks in advance for your help! Marc