Pressure Build Up in Fuel Tank During Hot Weather

[minuteman62-64]

I've got one of those EPA compliant 6-gallon plastic fuel tanks that don't vent to the atmosphere. I have been leaving the fuel line connected to the tank during storage. When it gets hot her (say the 90's) the pressure builds up in the fuel tank to the point where, if I don't remember to crack open the lid, the pressure floods the engine. Just sitting there the pressure in the tank is high enough that fuel seeps out around the fittings and, when the fuel line is connected, seems to push fuel all the way into the engine block.

​Just wondering what you guys with the 6-gallon plastic tanks do. Leave the lid slightly open? Disconnect the fuel line? Other?

 

[GA_Boater]

I pop the line at the tank or have the same problem you. It's part of my shut down as soon as the boat is on the trailer. Leave the motor idling. disconnect the tank line and by the time the boat is winched up the motor stops with dry carbs.

 

[MH Hawker]

i vented mine by drilling a 1/16 hole in the cap, or you can order a vented cap

 

[Tnstratofam]

I was able to unscrew the vent from the cap and take a pair of needle nose pliers and remove the rubber stopper from the vent screw. Reinstall the vent screw in the tank cap and now the tank vents as it should.

However I typically do like GA_Boater and disconect the fuel line while I'm loading which runs my carbs dry as I winch my boat up the trailer.

 

[Sea Rider]

I see many unvented fuel caps on newer OB's that literally turns fuel tanks into PIG tanks specially when boating on sunny days with exposed tanks or when leaving tanks under heated environments. To run carb dry is a must as won't know when your next outing will be..

Happy Boating

 

[minuteman62-64]

Thanks, guys. I'm going to disconnect the line and run carbs dry from now on.

 

[Fed]

You're not over filling it are you?

 

[minuteman62-64]

You're not over filling it are you?

Nope. Only a couple of gallons in a 6 gallon tank.

 

[gm280]

I always removed the fuel line on my boats (engines) and let the engine run until the fuel was used up. I never had an issue either. However, my 6 gallon new fuel plastic tank came with a vented cap to open for that reason. And It is a Moeller 6 gallon tank. :noidea: