fuel overflow line --- any way to avoid losing fuel

[ihaveabrownboat]

1980 17' Glastron. The boat accepts fuel fine. Actually fills surprisingly quickly. When it's full it pukes fuel back out the overflow fitting as one would expect.

Problem is the overflow line is a straight shot back to the overflow fitting. It's about a five foot line to the fitting on the side of the boat. This means that when the tank is very full, or close to full, acceleration pushes more fuel out the overflow. This happens on the trailer pulling away from stop lights or on the water taking off to get on plane.

I can't be the first one to have ever noticed this. After seeing mine do it I noticed two others doing the same thing. So it's not a novelty.

I checked and the overflow line is just a straight piece of hose. Has anyone seen a one way valve of some kind that would go closed under the force of acceleration but fall open when still? If not has anyone come up with some other solution? This has me curious so please share your ideas. Even the weird ones.

 

[cr2k]

Re: fuel overflow line --- any way to avoid losing fuel

It should have a loop in it to trap the fuel.

 

[ihaveabrownboat]

Re: fuel overflow line --- any way to avoid losing fuel

It should have a loop in it to trap the fuel.

This one doesn't. Nor is there room for it to with the placement of the fitting on the side of the boat. Also (with permission) I looked at eight others on the ramp. Three were straight hoses like this one.

I can readily understand how a loop in the return line would help to keep water from getting in the tank. There's no pressure from the outside of the line to force water beyond such a loop. But should there be pressure from the tank side (whether it be from acceleration or overfill) that would push past a loop with only a short rise. If it didn't the overflow vent wouldn't be an overflow vent.

 

[Bondo]

Re: fuel overflow line --- any way to avoid losing fuel

Ayuh,.... The loop is quite critical, 'n I've added Vent Whistles...

When the noise stops, shut the pump off, 'n No spills...

 

[geoff-nz]

Re: fuel overflow line --- any way to avoid losing fuel

Bondo, do you have a link to the whistle an a pic of the loop as my glastron has neither......cheers

 

[JEBar]

Re: fuel overflow line --- any way to avoid losing fuel

have seen fuel whistles in various shops but never have installed one .... sounds like a good idea

Jim

 

[Bondo]

Re: fuel overflow line --- any way to avoid losing fuel

have seen fuel whistles in various shops but never have installed one .... sounds like a good idea

Jim

Ayuh,.... Mine are Just like that, only green...

The Loop, goes, from the vent fitting, Up, over, 'n down to the tank...

The key is Up, from the vent fitting...

 

[JEBar]

Re: fuel overflow line --- any way to avoid losing fuel

The key is Up, from the vent fitting...

that would take a bit of pondering to figure out how to rig it that way in our boat ..

Jim

 

[ihaveabrownboat]

Re: fuel overflow line --- any way to avoid losing fuel

My old Glastron would have the same difficulty I think you're seeing. Just not space to make a loop up from the vent fitting that wouldn't kink the line.

 

[Frank Acampora]

Re: fuel overflow line --- any way to avoid losing fuel

While I can't remember the name, someone does make a ball check fitting that inserts into the vent line. While filling, air can pass freely but gasoline will raise the check ball, preventing flow out the vent fitting. Similarly, a surge during acceleration will close the check valve. Look around-- they may even sell it here on iboats.

 

[UncleWillie]

Re: fuel overflow line --- any way to avoid losing fuel

My old Glastron would have the same difficulty I think you're seeing. Just not space to make a loop up from the vent fitting that wouldn't kink the line.

Don't over define the "Loop".

I does not need to be a 360 degree Loop like a roller coaster "Loop the Loop".
It just need to rise above the vent fitting before dropping to the tank.
Think more like a very shallow upside down "U".

The Function is similar, but opposite of the "P" Trap under your sink.
Instead of trapping a small pool of water in the bottom, you want to trap a small air pocket in the top.

EDIT:
A picture is worth a thousand words.

 

[ihaveabrownboat]

Re: fuel overflow line --- any way to avoid losing fuel

Don't over define the "Loop".

I does not need to be a 360 degree Loop like a roller coaster "Loop the Loop".
It just need to rise above the vent fitting before dropping to the tank.
Think more like a very shallow upside down "U".

The Function is similar, but opposite of th "P" Trap under your sink.
Instead of trapping a small pool of water in the bottom, you want to trap a small air pocket in the top.

EDIT:
A picture is worth a thousand words.
View attachment 170424

Ahhhh....... Ok (he says in stupor and amazement), I don't have a loop. But I do have a loop. At least is that first illustration qualifies as a loop I do. Fuel still comes past it in a surge of acceleration though when the tank is very full.

Even with several repetitive hole shots probably never losing that much fuel. But it annoys me. Would like to find a solution if I can. That check valve mentioned above seems the obvious solution. Time for homework....

 

[UncleWillie]

Re: fuel overflow line --- any way to avoid losing fuel

Let us PLEASE Stop calling this an "Overflow Vent"!

Is is a "Fuel Tank Vent" who's whose primary purpose is to prevent the tank from collapsing as the fuel in the tank is consumed.
Fuel is NEVER supposed to Overflow out of it!

It is bad enough to spill it on the road!
Back in 1980 it may have just been seen as a nuisance.
Today it is a Federal Offense to "Discharge any petroleum product into the water."

If you Knowingly spill fuel when you accelerate "On the water taking off to get on plane."; that is an up to $50,000 fine per day and 3 years imprisonment.

This problem needs to be resolved! No Kidding!

Fuel/Oil Discharge
Under federal law (the Oil Pollution Act of 1990 and the Clean Water Act) it is illegal to discharge any petroleum
product into the water. By law, any oil or fuel spill that leaves a sheen on the water must be reported to the U.S.
Coast Guard at 1-800-424-8802. You are responsible for any environmental damage caused by your fuel spill.

 

[ihaveabrownboat]

Re: fuel overflow line --- any way to avoid losing fuel

Ahhhh....... Ok (he says in stupor and amazement), I don't have a loop. But I do have a loop. At least is that first illustration qualifies as a loop I do. Fuel still comes past it in a surge of acceleration though when the tank is very full.

Even with several repetitive hole shots probably never losing that much fuel. But it annoys me. Would like to find a solution if I can. That check valve mentioned above seems the obvious solution. Time for homework....

Stating that it's a problem merely restates the reason the thread was started in the first place. Doesn't really help to move anything along. Redundancy has a purpose though (I assume).

So, yes, it's a problem. It's a problem that is being asked about and isn't isolated. All that being so do you have a suggestion for a solution rather than a restatement of the problem?

The vent line can't be "looped" any more than it is. There's simply not room. There is no visual indicator to know how full the tank is getting. The fill line doesn't back up enough pressure to trigger the venturi in a fuel pump's shut off mechanism to stop the pump before fuel has started to spurt out the vent line.

Once it's that full it will wizz out a bit more under acceleration. Not a lot. But it's there. It's a problem I'm more than willing to address and am asking for ideas (rather than restatements that it's a problem and citations of Federal statute further reinforcing that it's a problem).

There's not a reroute of the vent line that's feasible. No further "looping" of the vent line is really feasible. The vent line does come up inside the hull cap before leaning back down the vent fitting. I've considered splitting the line there and putting a manual valve in the line. Could reach over inside the boat to open it during fueling or while boat is stationary on trailer and leave it closed during operation.

It's an idea. Not an ideal one as I'd prefer something more automatic for such a function. The auto racing community's check valves shut off for roll-over (or at least at greater angles of attack than simple boat acceleration). But so far I've not found any other type of check valve that would work.

So, anyone else have an idea?

 

[superbenk]

Re: fuel overflow line --- any way to avoid losing fuel

I installed one of those check balls. It works pretty well. They need to be installed mostly vertical so you need room for it. It'd fit on one of the vertical sections of the loop/U. I'm on my phone so I can't get a link but they are for sale here on iboats.

You should also learn how much fuel it takes to fill your tank from any given point & try to not fill it to the top. I usually fill my tank with a given number of gallons to get it close to full, not fill until it pukes. You can also watch the vent while filling and when you stop seeing the fumes (distortion of the air) stop filling immediately. I've tried that with varying success. Can't say I recommend that option.

 

[BobGinCO]

Re: fuel overflow line --- any way to avoid losing fuel

I LOVE the difference my Fuel Whistle makes! NO MORE SPILLS! And it took all of about 5 minutes to install.

 

[JimS123]

Re: fuel overflow line --- any way to avoid losing fuel

Years ago I calibrated my fuel tank vs. the gage. If it shows 1/2 tank, I know I have room for 8 gallons, so I add 7.5. If it's at 1/4 tank, 12 gallons, so I add 11.5, and so on. I only overflowed it once. Then I knew I had to do something.

 

[Another retired guy]

Re: fuel overflow line --- any way to avoid losing fuel

I've considered splitting the line there and putting a manual valve in the line. Could reach over inside the boat to open it during fueling or while boat is stationary on trailer and leave it closed during operation.

It's an idea. Not an ideal

So, anyone else have an idea?

Do NOT put a manual valve in the line. The VENT line must be open while the engine is running. If you forget it's closed you may collapse the tank

 

[Bondo]

Re: fuel overflow line --- any way to avoid losing fuel

I LOVE the difference my Fuel Whistle makes! NO MORE SPILLS! And it took all of about 5 minutes to install.

Ayuh,.... 'n it drives people Bonkers tryin' to figure out where it's comin' from....

Especially at a gas station, rather than a fuel dock...

 

[oldjeep]

Re: fuel overflow line --- any way to avoid losing fuel

I LOVE the difference my Fuel Whistle makes! NO MORE SPILLS! And it took all of about 5 minutes to install.

Sounds like a great idea - I'm constantly puking fuel during fills at the gas station.