crossing the river and i went under. i changed all oils and gas and dried fuse box the second day. started it up and ran fine for 30 min then blew the main fuse so i took hair dryer and dried fuses again and checked everything i could think of but when i plug in a new 30amp fuse it will blow in 5sec. any idea as to what i need to ckeck.

 

Sounds almost like water in a plug that's shorting it, to me. This is merely the opinion of an electrician in training, though. I'd check all your plugs (not spark plugs, your electrical plugs), blow the water out of them and try again.

Do you have a multimeter?