Gas Tank Venting Question

[78BAHNERMAN]

I have a 78 Bahner boat with two stainless steel 11 gallon gas tanks that have vented fuel fills. It is also vented through the hull. The vents that are through the hull leak fuel in to the boat when I take off or slow dow. Can the vents through the hull be eliminated and if so will the vented fuel fills be enough?
Any thoughts would be aprreciated.

[74sleek]

That would suck, sounds like they should have some kind of check valve in them or something.... I don't think my boat has vents on the tanks? It also has 2 tanks, with the fills on the top, but I don't think they are vented. Don't they need to be vented somehow to work properly? Since I bought my boat without a motor, and haven't put one in it yet I don't know if mine work right or not. I didn't see any vents anywhere.

[78BAHNERMAN]

My thinking is that since the gas caps are vented, that should be enough. I'm not really sure what the purpose of the two extra vents that go through the hull are for and if I even need them.

[squirt'nmyload]

i'm no expert but i would think that having just the vented caps would be ok

[MudPumper]

My boat has vented caps only. Plug up the other lines.

[67weimann]

Yeah, you only need the vented fills. I would eliminate the others. Mine only has the vented fills and they work great. They never leak anything since the vent is above the fuel level even when they are full.:D

[luv2race]

I have a 78 Bahner boat with two stainless steel 11 gallon gas tanks that have vented fuel fills. It is also vented through the hull. The vents that are through the hull leak fuel in to the boat when I take off or slow dow. Can the vents through the hull be eliminated and if so will the vented fuel fills be enough?
Any thoughts would be aprreciated.
I've never heard of gas tanks needing two vent. The fill vents should work fine. You just need a vent so the fuel pump doesn't pull a vacum. So block off the other vents and pay attention. the next couple times you take it out. See if the boat runs different.
www.R-DMARINE.com

[El Prosecutor]

A while back I filled the tanks and went out for a short test run. Came back with almost full tanks and parked on a slanted driveway. Next morning my wife smells gas "real strong" out by the boat - it was running out the vented caps down the sides of the boat onto the deck and dripping off the bow light onto the driveway. All of this was occurring underneath the boat cover, which is specially designed by WalMart engineers to trap gasoline vaoprs and create enough static electricity to produce a spark. :2purples: :2purples: Fortunately, this unit was defective and insufficient spark was produced to actually cause combustion of the vapors.

[74sleek]

I'll look tommorow, but I don't think my fill caps are vented...
As far as the "two vents" go, I wonder if his tank has a return line that someone turned into a vent? Without a check valve....

[OverKill]

I in fact have one vent line on my 30 gallon belly tank. Last summer I feaked out, I was out at my place in Big River with a full tank of AV gas. It was about 110 outside and I noticed it started to smell like raw AV gas. So I went on the other side of boat where the vent exits the boat. Low and behold that side of the trailer was soaked with AV gas. So yes put a vent line in, because when its a 110 outside you don't want that gas to expand and have no where to go. Thats what they are there for so use them.

[jetboatperformance]

78bahner Its not unusal for older boats to be set up that way but the guys here are correct your caps ,if vented should be fine by themselves and thus you could eliminate the vents. However... if you want to keep the bulkhead vent and space allows ,splice a discreet piece copper tubing in a 360 degree loop in the line between the tank and vent above the level of the tank which should help alot . Poor fuel tank venting along with for example,two tanks flowing (T'd)together,restrictive lines,incorrect filters, cracked fuel lines etc are the source of loads of performance and safety problems seen regularly . Even properly vented tanks will occasionally "burp" out fuel when overfilled ,in the heat (expansion) or the boat is setting "bow down",sometimes making a real mess of paint,gel coat etc. Good Luck Tom

[74sleek]

My boat has some heavy chrome caps that have a spring loaded "clip" that holds them shut. I may have to post some pics of them, but I don't think they are vented... If they aren't do I change my caps or do I just vent the tank some other way?
Going to look at it in a minute.

[lilsquirt]

My boat has some heavy chrome caps that have a spring loaded "clip" that holds them shut. I may have to post some pics of them, but I don't think they are vented... If they aren't do I change my caps or do I just vent the tank some other way?
Going to look at it in a minute.
Those caps are vented, you should be fine. I have the same set up on my boat and the only time I had a problem is when I filled the tanks all the way up the tubes almost to the cap on a cool day then parked it in the garage on a hot day and the fuel expanded with no where to go and it popped the cap open. If you keep the fuel level down to the bottom of the tubes coming out of your tank you wont have a problem.

[74sleek]

Cool, thanks for that advice.

[kcsteck]

on my boat, my tanks dont have a breather and have the scew in caps. after going for a bit sometimes it builds so much presure in the tanks it kills the motor. I relase the pressure in the tank and it goes again. How should I remedy this problem drill small hole in the caps?
Casey

[uLtRADeNniS]

If the tanks vents are not working properly.. Will this cause the gas to expand in the heat, forcing the fuel past the floats, thus causing the boat not wanting to start??
I have an issue with my boat not wanting to fire up after sitting in the water for extended times??

[Unchained]

I had problems with the vented filler caps before.
The boat sat so low in the water that some water would want to splash up onto the caps and get in the tanks. Then the motor would run bad until it purged the line.
I have had better luck with the vent right on the tank.
It's important to have a line on the vent fitting and have it be as far above the tank as you can get it.

[it'sjustaboat]

WOW Hot boat has a forum?? Yea it's my first reply. Did it ever dawn on anyone that the fuel fill's were changed. And it just might be that the only thing around was a vented fuel fill. Maybe one of the old owners had them sitting around and put them in. Hell the boat is a 1978 right. Plug up the vent lines and you will be ok.

[GunninGopher]

I also could be that the tank "vents" are actually return fittings.
There is good advice in this thread:
Don't overfill your tanks!! (and watch the hill parking, too).
I need to be reminded once and a while.

[uLtRADeNniS]

so should I drill a hole in the in the top of the fill cap? Or...??

[it'sjustaboat]

so should I drill a hole in the in the top of the fill cap? Or...??
NO!!! At one time in this boats life the fuel fills were non venting. If you want you can buy some non venting fuel fills and use the ones built into the tank. Or the quickest thing to do is put a bolt into the vent line (size of the hole) and then put 2 hose clamps on it. And then just leave it. But then if you have through hulls you will want to plug those as well. Just fill them full is sillycone. Done deal.

[Xlration Marine]

You could. That would be the cheepest way to take care of it. Or if you feel the need to keep it the way it is, buy some new hose, and long enough to make a couple of loops in it. The loops will keep the fuel from coming out, and run back into the tank. I have vented caps on my boat, and I get a little bit of fuel coming out of them, wish I had vented it through the hull. If it were me, I would get more line and put loops in it. Good luck.

[uLtRADeNniS]

I have screw in caps thats are vented. The boat sits so low in the water that water gets in there and blocks the vent. When I go to open up them I hear pssshhhh...:D
I will try to run a hose from the tanks and loop it up like you said