Fuel tank install - level or tilted?

[Fisnfool]

Since my 19 foot boat with a I/O sits stern down in the water, should a fuel tank be installed level to the deck or raised in the rear to allow a better fill? My tank is a moller 19 gal installed under a rear seat and vented through the hull.

A friend mentioned I should tilt the tank, but that does not sound right to me. A max filled tank would just spill fuel overboard as the stern goes down with increased throttle. Am I thinking correctly?

Tanks model is: Product # 032519 19 Gallon Permanent Fuel Tank

http://www.moellermarine.com/aftermarket/fuel_storage_tanks/permanent_tanks/

 

[Silvertip]

Re: Fuel tank install - level or tilted?

Why should it spill fuel. Do you not have a cap that seals tightly and does the tank vent have a rise before exiting the side of the boat. The tank does not have to be tilted. Below deck tanks are not installed that way and above deck tanks don't need to be either.

 

[fixb52s]

Re: Fuel tank install - level or tilted?

Do not install it tilted. Flat is how they are installed at the factory. Some rubber strips installed between the hull and the tank should be installed. When this is full of fuel, you want it supported with the most surface area you can get. Also ensure it is correctly strapped down.​

 

[Fisnfool]

Re: Fuel tank install - level or tilted?

Why should it spill fuel. Do you not have a cap that seals tightly and does the tank vent have a rise before exiting the side of the boat. The tank does not have to be tilted. Below deck tanks are not installed that way and above deck tanks don't need to be either.

There is a rise to the gasketed tight fill cap on the stern of about 20". About 16" to the vent.

I can see how this would not spill while running. If the tank is maxed out while fueling on the trailer, by watching the translucent tank fill, fuel does trickle a very small amount as the fueling is stopped. Now that I think about it, this would be from the fuel in the fill hose dropping into the full tank and rising to the vent because the fill hose is taller and larger diameter. So max fill is actually below the rear edge of the tank top to allow for gas in the fill hose. Trailer is set up to allow water to drain if towing in the rain. This causes the fuel to reach the top of the tank at the rear while front still as about an inch or more to go.

Seeing the slight spillage made me wonder about possible spill while running. But in reality it was a Operator Error at the gas pump.:redface:

A fuel proof rubber pad about 1/4" thick is under the tank. The tank is locked down by 4 of the manufactures stainless steel clamps that fit into groves molded into the tank. All fittings, hoses, and gauge sending unit are double grounded.

Thanks for the comments.