Fuel leaking during storage in sun

[RustGuy]

I have 2004 Yamaha F15ELHC. Recently I have found quite a bit fuel dripping from the powerhead lower case and I can't pinpoint the source. It only happens when the portable tank (new EPA manual vent style) gets hot and swells with the hose connected to the motor. Is there a check valve at the float that's supposed to prevent this? Otherwise the motor runs perfect, well serviced, and never leaks fuel while running or with the hose disconnected. Any suggestions for a DIY fix? I'm no stranger to engine repairs but not that experienced with outboards.

Thanks

 

[robert graham]

Crack open the gas cap about 1/4 turn when your boat/motor is sitting out in the sun to relieve pressure building up in that new tank....

 

[99yam40]

I have had a primer bulb rupture and fill the back of boat with gas by tank not venting sitting in the sun..
Best to keep tank out of the sun
cover it with cushions or life jackets or unhook from the tank if possible.
Not many of them have connectors on both ends anymore

 

[RustGuy]

Thanks Guys. The tank was under the boat cover and the temp was only 68 or so here on the Oregon coast so it wasn't like it was all that hot. I think I'll just disconnect the hose from now on. Glad I don't have to replace anything in the carb. I'll try cracking the cap also when storing it.

 

[99yam40]

That being all said , the float should close the needle into the seat sealing it off and not allowing more fuel into the bowl.
Would not hurt to inspect or replace.

 

[robert graham]

Those new EPA ventless tanks can/will build up pressure and force fuel past fuel systems O-rings, seals, gaskets, etc.....just crack open the cap, keep the tank full and you should be fine.....

 

[dingbat]

That tank can't generate enough pressure to open the float valve unless the float going bad or something is stuck in the seat. They will also leak if the motor is tilled off vertical.

I recommend tearing it down to investigate before it manifests into a bigger problem

 

[RustGuy]

Sounds like I need to take a closer look at the float/check valve when I quit salmon fishing and store it next week. I've trolled twice now for several hours after the leak and not a trace of fuel since. I haven't looked that closely yet but isn't the check valve on this carb independent of the float? From the illustration it looks like the check valve is opposite the float hinge on it's own vertical float. The motor is always stored in a vertical position. I found the fuel did drip directly from the carb so that check valve is definitely suspect. I don't think it would be a problem with the older type auto-pressure release vents on the tanks.