Potentially dangerous fuel system issue

[998cc]

All. This isn't a question, and it may be in the wrong forum.

I walked into the garage this morning and was met with a strong gasoline smell. I immediately opened the garage doors to vent the fumes and went looking for the culprit. What I found was the outside stern of my boat damp from gasoline running out of the vent for fuel tank.

After considering the situation, the cause became clear. The location of both the filler tube and vent tube are located next to each other at the rear of the tank. Combine this with a fairly full fuel tank, and the front of the boat being raised high enough above level to concentrate the fuel at the rear of the tank set the stage for this potential mishap.

The final element was the weather. Yesterday was a very warm day which was enough to expand the fuel/vapor in the tank; this pressure could not vent due to the tank vent fitting being covered by the liquid fuel in the tank. The result was the spill.

The fix was easy. Drain 5 gallons of fuel and lower the trailer jack, so the bow is slightly pitched down.

The danger of this situation was the location of the boat in the garage. The spill was only about 10 feet from the gas water heater.

1972 Gulfstream, MC-1 with GM Inline 6, 250

Russ

 

[Dave-R]

You would think that the vent hose would have a high bend that was above the fill opening to prevent that. I think you are very lucky to have caught it when you did.
Dave-R

 

[Eric 3.7LX Alpha 1]

Just a FYI.. water heaters actually have a safety built in them now, have been for about 8 years maybe. The flame in the heater is separated by the room by a special flame shield. Air can get in, the flame can't get out. If you have a push button clicker on the heater to light it pilot and have to look thru a piece of glass to see it, your safe. I've watched videos of these heaters in a controlled room with gasoline in it. The gas vapors get in the burner area and ignite, then extinguish themselves out without an fire getting outside the heater. It's called FVIR or flame guard. All heaters in the country sold have to have this now for quite a few years, but there some still older styles out there in use...

Of coarse if you have a boiler or furnace near the water heater with an open flame, all bets are off.... Here in MA, a gas applance in a garage has to have the burner 18" off the ground. Usually raised on a stand.

 

[poconojoe]

Thanks for the heads up. We always store our boats bow up so any possible water can exit through the transom drain hole.
You are lucky to come upon that. Heck, many things could have set that off.
Is that garage attached to your house?
I'm thinking that maybe your tank was too full. They say leave some space. Not to fill it to the top. Maybe this is why? Never thought it was a big deal, but I guess it is!

 

[Chris1956]

Russ, what you describe is pretty common. Some boats have the vent in the bow, and after every wave, a "shot" of fuel exits the breather, when the tank is full. There is no cure I know of, short of some sort of pressurized fuel system, such as on the newer cars. The newer cars have a pressure gas tank cap, a charcoal canister and some vacuum tubing to burn any fumes from the tank.

I think the guideline is that if you plan to store the boat indoors, don't fill the tank all the way...

 

[998cc]

Eric. Perhaps the needed replacement of our water heater 2 months ago was a blessing. It is on the 18 inch stand as well. I won't fill the tank up again!
Thank you all.
Russ

 

[PatinIdaho]

I have the exact same problem except mine is outside in the summer. Came home the other day and gas was dripping out the vent. I would guess by the wet area size 2 or 3 gallons has dripped out.
I have seen fuel fill fittings with the vent hose attached to it so there is no direct vent but if the main fill hose is full from expansion i don't think it will help much.

 

[airshot]

A few years back had a similar situation only two fold. Not only did I have fuel dripping out the vent but also had water getting into the tank thru the vent. Long story short.....having discovered the vent line was a direct, straight and flat hose to the exterior vent I began to rationalize the problem. Slightest pressure from heat caused expansion and while underway any spray that hit the vent was shot into the tank... So replaced the vent hose with a much longer one and created a large loop in an upward direction which solved both problems. Any spray into the vent had to climb to far up the loop so it drained back out.....any pressure from heat expansion was not enough to push the fuel around the loop so no more fuel escaping. You might consider the same thing on your vent line if you have enough room for a large loop.

 

[UncleWillie]

... The location of both the filler tube and vent tube are located next to each other at the rear of the tank. Combine this with a fairly full fuel tank, and the front of the boat being raised high enough above level to concentrate the fuel at the rear of the tank set the stage for this potential mishap...

Over the years they figured out a solution.
My 2012 boat has the vent double plumbed to both the front and rear of the tank.
No matter which end the air bubble in the tank floats to, it will be under one of the vents.