2005 40hp 4stroke

[D92newman]

I have a 2005 mercury 40 hp 4 stroke motor cranks fine when first get to water. I can go across lake and fish for a couple of hours and when I go to crank it it will flood out. You can let it set for about 10 minutes and it will crank and run fine PLEASE HELP

 

[D92newman]

Please help I need this problem fixed