Bushwacker- I filled boat with fuel this morning on trailer and no vent problem nor fumes in bilge so, I am thinking that the problem is angle of the tank while on the trailer. Tank was only 1/2 full before pumping 20 gallons this morning. I will use the level to see the difference in angle. I had a brand new sending unit installed 2 years ago when hanging new 250 4 stroke Yamaha don't think that would be an issue (I will check though). I am going to cut a access plate in order the check hose clamp at fill cap. I think that maybe when I had fuel backed all the way up the fill hose that there might be a loose fitting around cap?
bigeasy1 - I will look for insects clogging vent too. A few months ago noticed motor pisser wasn't pissing from the cooling system tube; stuck a wire into see if anything was clogging it; a little something came out and water started pissing again. Whatever it was that crawled up there sure smelled horible on the end of my finger when it came out!!
I'll be sure to use someone elses finger this time when I check the fuel vent.
Thank you both.