Ways to minimize fuel spraying from vent line when filling?

[adamjr]

Pretty much what the title says. When I fuel my boat and when the tank is near full gas sprays rather violently from the vent line. The first time it happened I was caught completely unaware and was drenched from foot to knee on one leg.

The set up is pretty simple. I have a 1965 Clipper Craft 16 ft. runabout. The fuel tank is an aluminum 18 gallon. The vent line looks to be somewhere around 1/2" hose and the nipple sticks straight up from the tank. The vent fitting is the standard type with a hole in it pinting aft and downward and it is on the side of the boat a few inches down from the cap. Likewise with the filler neck which is whatever the standard fuel filler hose size is. Both nipples are on the port side of the tank. They are fairly close to each other, something around a couple of inches.

Is there a way to minimize the issue? Is there a special fitting or a trap of some type that would reduce the pressure or maybe a check valve of some sort?

Any suggestions would be appreciated.

 

[dingbat]

Re: Ways to minimize fuel spraying from vent line when filling?

Sounds like your vent hose might be partically blocked. Remove the vent hose from the tank and blow it out.

 

[adamjr]

Re: Ways to minimize fuel spraying from vent line when filling?

Thanks for your rapid reply. Am I correct then in thinking that it shouldn't spray out? Being this is my first boat what SHOULD I expect when the tank is full?

 

[109jb]

Re: Ways to minimize fuel spraying from vent line when filling?

If the vent is lower than the filler neck then that is one part of the problem. If you are trying to top off after the auto shutoff nozzle trips the first time, that is another part of the problem. To prevent a spill I have seen people wrap rags around the vent and I even saw a guy that slipped his boat and fueled at the marina that had a catch pail that he hung from the gunwale of his boat below the vent.

 

[a70eliminator]

Re: Ways to minimize fuel spraying from vent line when filling?

I fill my 40gal. full blast from the pump and autoshutoff does the rest never have anything but vapors spill from the vent, you definately have a vent issue, what happens if you fill it slowly?
By the way my vent is lower then the filler neck, the filler neck is on the top of the gunnwale and the vent is below on the side of the hull.

 

[Bob's Garage]

Re: Ways to minimize fuel spraying from vent line when filling?

Every boat I have ever had had this same issue when over filling or when filling with a fast flow pump.

Resolutions for this problem can be either making an educated guess as to the needed amount of fuel to be taken on, and not exceeded it or a physical change in the vent system.

You will find 2 items on this site, www.greenboatstuff.com, a vent whistle and a catch bottle.

I use the whistle on my boat with twin 55 gal. tanks and am quite satisfied. However I have noted that they do not work with every type pump. The higher that fill rate the better they work as they rely on air being forced thru them to produce the whistle. It can be quite loud and some people are embarrassed by the attention they attract.

The bottle would be a more positive but reactive approach and would require a surface with enough surface area to hold the suction cups and a good seal around the vent.

A check valve would seem like a good approach but I do not recall seeing one for this purpose. They would certainly have their own short comings I am sure.

Meanwhile, be pro-active and slow your fill speed, let your tank purge the air as you fill the tank, and listen for the change in the sound of the filling tank.

 

[adamjr]

Re: Ways to minimize fuel spraying from vent line when filling?

My setup is like 70Eliminator's. I fill at a slow rate and the auto-shut off has never kicked on the pump.

 

[a70eliminator]

Re: Ways to minimize fuel spraying from vent line when filling?

On my chap the tank sits midship, the filler and vent is forward near the bow section on the gunwale, the vent tube makes a big loop before it attaches to the hull fitting, all well above the tank, Chaparral did a pretty good job installing the tank fill system.