Replacing a fuel tank vent line

HenryB

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Dec 8, 2012
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244
I am replacing the fuel tank vent line on my 18? C.C., 1989 Winner.

It was designed with a negative loop, about 4? below the top of the tank before exhausting overboard. It trapped gas and was a pain because the filling had to be slow or it burped fuel out of the fill pipe.

I?m thinking of using a vent line long enough to loop about 2? (Inside the console) and above above the vent then directing the line back down to the same path as the original, about 4? below the tank.

The loop height will be about 8? above the fill tube on the gunnels. I?m thinking that should be high enough so the fuel will come level with the fill pipe before it reaches the height of the loop.

That sound right?

Another thing I might do is vent from the side of my console (in board), but it would require some sort of catch bag, in the event vented gas were to happen, which I have not figured out how to do yet.
 

Don S

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62,321
Re: Replacing a fuel tank vent line

Any time you put a loop in a vent, there will be a low spot for gas together.
Keep the hose at a steady incline going up above the vent and then drop back down to the vent.
That hump will prevent water from going into the tank, and there is no place for fuel to lay and prevent air flow.
Here's a quick drawing to show what I mean.

Untitled1.jpg
 

Bondo

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70,525
Re: Replacing a fuel tank vent line

Ayuh,.... I put a loop in mine, but with the loop, Up, so's it'll drain both ways, 'n not hold any liquids...
 

UncleWillie

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Oct 18, 2011
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Re: Replacing a fuel tank vent line

...Another thing I might do is vent from the side of my console (in board), but it would require some sort of catch bag, in the event vented gas were to happen, which I have not figured out how to do yet.

Venting Gasoline in the form of liquid or vapor needs to Go Overboard.
Gasoline fumes are heavier than air.
Unlike in a car where they will drop out the bottom onto the pavement; In a boat they will build up in the bilge.

Do not vent them inboard, just because you can not see them does not make it a safe thing to do. :eek:
 

HenryB

Petty Officer 1st Class
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Dec 8, 2012
Messages
244
Re: Replacing a fuel tank vent line

I’m pretty sure with the top of the loop, to be 8” above the level of the fill tube at the gunnels, that no fuel will reach the height of the loop and drain down to the negative loop. I’m hoping not, anyways.
 

JoLin

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Aug 18, 2007
Messages
5,146
Re: Replacing a fuel tank vent line

No spilt gas, 'n they drive by-standers absolutely Bonkers at gas stations, or fuel docks..... :D :D

I'll second that. I put one on my 21' Pro-Line that had a 90 gallon tank. Drove ME nuts. The bigger the tank the longer everybody has to listen to it. They do work, tho...
 

Home Cookin'

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May 26, 2009
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9,715
Re: Replacing a fuel tank vent line

I like the vented fill caps. I had a through-hull vent go bad and let water into the tank, so I bypassed it and installed the vented cap.
 

HenryB

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Dec 8, 2012
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244
Re: Replacing a fuel tank vent line

The problem that I have (I think) is that the original vent line (the one I want to replace) runs from the tank vent down about 8” and then back up to the gunnels, thus trapping gas in the lower section (?) and causing fuel to belch out of the fill pipe.

I am going to temporarily install a clear plastic tube about 5’ long running up from the tank, through the console, to see what is happening when I am filling.
 

Grub54891

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Jun 17, 2012
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5,914
Re: Replacing a fuel tank vent line

Fuel vapors will still acumalate inside the boat. I dont know about you but it could be dangerous. Let alone smelling fuel at times.....
 

HenryB

Petty Officer 1st Class
Joined
Dec 8, 2012
Messages
244
Re: Replacing a fuel tank vent line

I appreciate the concern, but I intend to run the temporary clear vent line up and out through the console so it will vent well away from the bilge area. And it will only be used once when filling the tank so I can see if something strange is going on.

By the way, in order to gain access to the vent line path, which runs under the floor (and for some reason the existing vent line is hard attached somewhere under the floor and it will not move) I am cutting an 8" access hole in the floor to gain access. Perhaps an owner of a 1989 Winner 18 foot CC is out there with the same problem and could help me out.
 
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