Only getting them when i run off the main tank, No fumes when I use the other tanks in the rear...only at WOT. What could be causing this . Anyone?

mcpro...we have more than 1 fuel tank? How are they configured?

a cracked line coming from that tank. a hose clamp broke off like the cheap ones always do over time.

maybe your tank vent hose has come off in the gunnel.

Where are the fumes specifically? You kinda left it wide open. Where does your fuel return? Did you check the carpet in the gunnel to see if it gets soaked at wot?

Fuel in bilge? Yours may be different but mine has a small access panel for the sending unit under the bench seat. Can you smell it coming from there if you have it?

Aluminum fuel tanks fail all the time in boats where there is ANY water standing around or under them. If you clean your boat and have residual water make its way under the tank while it's parked... U pickin' up what I'm throwin' down?

The nature of the wind and air movement might only put the fumes where you can smell them at wot. However, it may be leaking a little all the time.

Sorry Chad! We are going to have to ask you to cut your boat apart.

Imma check up inside the gunnel for the breather hose.. Not sure how fumes could come from there when you are taking fuel out of the tank.. Also I will take the black cover out from under the back seat too. Until I figure it out, I will be running off the rear tanks only. ( Glad they were installed by the previuos owner)

That's why i asked where your fuel return goes. Not common but if it returns to the tank then that would be a consideration for a place to start looking.

You never know what a previous owner did..

We tried returning mine to the tank for a while but it did not work so put it back to fuel filter.

most likely a rotted bung due to dissimiliar metals as fountains use s.s pickups in aluminium tanks

Where is the bung?

Should be somewhere near that access panel. The bung and sender in mine are next to each other. Yours may be different.