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"THE ADVOCATE"
04-12-2011, 09:50 PM
My fuel tank vents were mounted on the side of the hull about 1 inch above water line. I didn't like that because I was worried about water getting into the fuel tank. I have already changed the 5/8" hose to ? and am wondering where others have their vents. I plugged the old holes on my hull rebuild. Thanks Jason.

H20MOFO
04-12-2011, 10:04 PM
Some caps are self venting....as far as I know mine are :cheers:

David
04-12-2011, 10:05 PM
mine too

"THE ADVOCATE"
04-12-2011, 10:16 PM
Excellent!, thats what I wanted to hear! Less mess less worry. Just wanted to know they work.

wolfie
04-12-2011, 11:36 PM
I have the vented caps as well. Sux when you're parked downhill with a full tank though!!! :biggrin:

David
04-13-2011, 06:59 AM
I have the vented caps as well. Sux when you're parked downhill with a full tank though!!! :biggrin:

Ya it does, or just a hot day and the fuel expand!!!
I've learned that when the pump stops I don't top it off and leave a little room for expansion...

Kona Kandi
09-23-2011, 02:54 PM
That works every time.

Hans
02-21-2013, 07:20 AM
My fuel tank vents were mounted on the side of the hull about 1 inch above water line. I didn't like that because I was worried about water getting into the fuel tank. I have already changed the 5/8" hose to ? and am wondering where others have their vents. I plugged the old holes on my hull rebuild. Thanks Jason.

The problem with the fuel tank vents in a boat is.....fuel vapor is more heavy than air. In a car under the engine and fuel tank is fresh air and the vapor can go there, but in a boat it will stay in the bilge.....a little spark and that was it.
The vent to the outside is o.k., if there is a valve in the hose that let go expanding gas to the outside and blocks anything to go inside. A second vent is needed inside the boat at a place where it's protected from splashing water, with a valve the opposite direction to give air streaming into the tank to compensate the used up fuel.

White Lightning
02-21-2013, 09:29 AM
What I did in my Kona was: first I replaced the vent screen on the outside of the hull and pointed the screens toward the rear, one at 2 o-clock and the other at 7 o-clock. Then on the inside I replaced the vent hose with a piece of fuel tank vent line (either 5/8" or 3/4" I cant remember what size fit it) and made a big loop in it and then into the tank. What the loop does is prevent any liquid (either gas or water) from getting in or out. If any water gets into the loop it just sits there until it evaporates, same with the gas, it'll just sit there and let the fumes push past what ever liquid is in there and vent. Eventually anything that's in the loop evaporates, meanwhile it acts as a p trap and won't let in any debris (dust and such). Hope that helps.
Rob

Sleek Freak
02-21-2013, 05:11 PM
leave a high spot in the vent line to keep the water out, or use a vented cap. never vent a gas tank inside a boat.

heyyou325
02-21-2013, 05:55 PM
My boat is probably a bit higher out of the water than the other boats here. But my vents are about 1/2 inch below the rub rail on top of the gunnel on each side, about 6 to 8 inches in front of the transom. I also have vented caps. Without the vents in the side, I have a hard time filling the tank without spilling fuel . My jet has 1 1/2 inch rubber lines, and the fuel will overfill the lines and burb out if I fill very fast without the side vents. My other fishing boat has 1 1/2 inch lines, going into the tank at 90 degrees, with only a cap vent, and I can't fill at fuel pumps without burbing out the top all the time. If I open my gauge line in the top of the tank, no problem filling, except I can't see the gauge outside the boat, so I don't know how much to put in. In either boat. I am going to put side vents in my small fishing boat this spring. But I still need to figure how to fill without overfilling, especially after the boat sits in the sun awhile. They never put the gauges where you can see them. Ruined 2 paint jobs last year with gas coming out the vents, and it's vented at least 18 inches above the tank. That loop sounds like a good idea.

White Lightning
02-21-2013, 11:05 PM
Lol, personally I don't have to worry much about the gas warming up in the tank.........it's never in there long enough!! lol Mileage????? What's that?? :confused-smiley-013 I think my fuel consumtion could be calculated in gallons per second lol.
Rob

PHOENIX
02-22-2013, 10:14 AM
It seems very few gas tanks have baffles and they should. In that they don't, the gas can get to sloshing pretty good, especially when trailering.
In a previous boat, I tried just about everything to stop gas from spewing out the vents on the sides. Couldn't fill the tanks over 3/4 or out it'd come.
Using the alcohol free gas from the marina (which also had more octane than regular), it would really mess up the paint. Had it been gel coat, it would certainly have dewaxed it. I tried the loop in the hose, a restriction in the hose, like a small filter, nothing worked. These vents actually need to be a couple feet higher than the tank to work well. Not possible with a low profile hull. I finally decided the main problem was the gas that entered the vent hose couldn't drain back into the tank fast enough. Therefore, installed a much larger hose so it could drain back faster. It also served as a small reservoir until it could return to the tank. This worked pretty good as long as the tank wasn't filled to the top.
Present boat has the self venting fills with a 2" hose straight down to the tank. The self venting caps work real well as long as you keep a good gasket and spring in them.