Fuel from vent when stored

[Tforgey]

Fuel leaks from gas tank vent when stored,even with tank half full,and gas cap loose.why isn't tank venting his can't be normal.and it's a hazard.anyone experienced This? Help appreciated

 

[Tforgey]

This is on 87 force 85 hp

 

[GA_Boater]

Is the tank a portable or built in?

 

[pnwboat]

If you are referring to the on board built in tank, I've experienced the same thing. I have a 20 gallon built in tank. It's only about 9 inches deep, which I think makes it difficult to vent and get an accurate gas gauge reading. If I crank the jack handle on the front of the trailer all the way up, and tilt the bow up high while stored, I experience the problem that you are describing. If I set it level or just barely tilt the bow up while stored, the problem goes away.

 

[Tforgey]

Shouldn't tank be venting all the time?it's a built in tank.it certainly should be venting,with gas cap off.it can't be plugged up or fuel wouldn't come out.if this is normal,it surely seems dangerous

 

[Jiggz]

Technically, you are correct. The vent line is located at the top of the built in tank and is designed to be always venting although it does have an inverted "P-trap" like curve along the line. You might want to double check to make sure its point of attachment on the tank hasn't broke off and pushing it into the tank.

 

[pnwboat]

I've looked at the inside of my tank as best I could through the opening for the sending unit by the fuel fill and vent attachments. The fuel fill and vent attachment are both at the very back of the tank towards the stern of the boat. There is a vent tube inside the tank that goes towards the front of the tank. I can't see the whole length of the tube inside the tank but as far as I can tell, it looks intact. It's definitely not plugged. I suspect that due to the shallow depth of the tank, the factory venting set up doesn't work as well as it should. Regardless, I don't really want to tear up the deck to inspect the tank so I just don't tilt the bow up to maximum height which seems to work fine.

 

[Jiggz]

That is some good info. If the internal vent pipe for the vent tube runs to the forward of the tank, then the only reason liquid fuel will flow out of the vent tube is if the said pipe has holes or cracks in it at the aft or stern part. This is especially true if the fuel leaks out only when the bow is raised.

With the bow raised, the liquid fuel runs aft raising its level and probably leaking into a hole/crack on the internal vent pipe aft section flooding the tube. Since gas vapor continues to create positive pressure inside the tank, the liquid fuel that leaked into the vent pipe is pushed out to the vent tube.

Of course, that is all theoretical. Now if such theory is accurate, then is it possible that when running the boat liquid fuel continues to leak from the vent tube especially before planing?