Fuel Vent Barfing Gasoline

[IDoSeaDoo]

Hey guys, does your boat barf fuel out of the vent when you top off the tank? I have a '97 Challenger 110, but it's similar to the Sportsters and Speedsters of that era. I believe I'm missing that accordion fuel neck hose that I've seen on some skis. I'm talking about that plastic hose inside the fill tube. I believe that somehow it stops the nozzle before it's able to overfill the tank. It's never been there, I believe it was removed by the PO as the boat has always done this.

 

[XP 787]

Don't think I have ever seen fuel come out of vent but I have had it spray out of the fill tube when topping off without it stopping the nozzle and I do have that accordion in my fill tube. 99 Speedster.

 

[anshad]

Yeah, mine does it when I fill it. The pump clicks, and then about 5 secs later it pukes. If I fill it on the low setting on the nozzle, it wont do that.

 

[IDoSeaDoo]

@anshad do you have that accordion tube in your fill neck?

 

[anshad]

Not sure. It is under the cover. I will look today or tomorrow.

 

[anshad]

Yeah, there is the accordion piece in there. I think it only does it when there is a surge of fuel to it.

 

[IDoSeaDoo]

Well, the problem is that the tank gets overfilled. I have a theory that the accordion is supposed to make the pump click off before the big 3" fill tube gets full, leaving half a gallon or so of void space. The fuel level would then be below the bend in the Vent hose, and hence make it more difficult for fuel to go up and out of the vent. I 've seen my vent leak fuel driving down the road, and also in the water once. This is extremely troubling to me and I am looking for a way to mitigate this. The best fix would be to move the fill neck down somehow, but the geometry of the hull doesn't really allow it, unless I have it on the side of the boat. Aside from being ugly, I feel like this would invite the possibility of letting water into the tank as this boat rides pretty low when not on plane. If I fill it slowly, it will only spew a little form the vent and that's when I cut it off, but I believe I still leak a little when the boat jostles in the water before I burn some off. Also, it takes forever having to hold the pump at slow speed. I've gotten pretty good at guessing when to slow down, but the engineer in me knows this is not a real solution.

 

[anshad]

Yeah, I think more than anything that it is a "compliance piece". It looks like it is a one way valve from what I can see, but I have never seen it leak pulling it to the lake with a full tank, or while out on the water with a full tank. I just checked the tank for water before I filled it for the winter, so I have to assume the one way piece of that vent is working.

 

[IDoSeaDoo]

The vent is not a 1-way valve, just a hole covered with plastic to avoid direct spray. You can blow through it both ways (I've replaced mine). What keeps the water out is the bend up in the vent line. The line goes up to the top of the hull, then back down. Water would have to travel all the way up before it would go over the apex and down into the tank. Fuel and the vapor in the tank expand and contract with temperature, and hence need to breathe both ways. My fuel tank is self made, but I copied the fill and vent parameters of the OE tank. The shape is different though. The edge is not square, but rather triangular, with the bottom coming up at an angle to meet the flat top. Picture can be found here: Challenger 4tec Upgrade
I built it this way to maximize volume, as with the old tank, I was always running out of fuel.

 

[bledt]

My '96 Speedster started doing it last summer..... every fill up. Never remember it happening before!!

 

[wrench2ride]

if I remember correctly I am pretty sure the corrugated tube inside the filler neck is to allow air to escape while you are filling, the tube goes into the tank past the filler hose so once you have your tank "full" with an air space in the tank yet the filler tube will fill up and shut the pump off and air can get around the outside of the corrugated tube and filler neck so it doesn't spit the fuel back out at you. without that corrugated tube you will be able to fill the tank up too full and there won't be any room for expansion and you will see fuel come out of the vent on the side or it will spit out when filling. it is important to note that if you fill very slowly you will be able to over fill the tank even with the tube in place. just like your car when the pump shuts off you typically shouldn't keep filling.

 

[IDoSeaDoo]

Well, I'm finally back home. Took the boat out Sunday, and noticed the tube IS there... Now I'm perplexed... Also, if I fill at full speed, it is guaranteed to spit fuel out at me, as well as out the vent. If I fill slowly, it spits just a little bit out the vent and I shut it off. If I get lucky, I can only spill a drop.

 

[wrench2ride]

are you saying that when the tank is half full it is spiting out? or when you are topping it up when it is full and it's spitting out?

 

[IDoSeaDoo]

When I'm filling up and the tank reaches max capacity, it always spits out the vent. If I'm filling full blast, I'll get a huge gusher out the fill tube as well as the vent. I usually have to go like 1/3 speed after the last bar on my fuel gauge lights up, at which point I have probably 8gal more to fill (custom tank). I ran the vent line up as high as it would go near the fill , probably level with it, and then back down to the vent itself.

 

[wrench2ride]

I would say that is probably normal, the fill tube just can't keep up with how much fuel is coming out of the nozzle. you could try moving the position of the nozzle when you are filling, I found that helps on some units. when I am filling my boat once it is getting close to being full the sound of the air coming out of the vent changes so I slow it down until the pump shuts itself off. it takes a lot longer to get the last few gallons in but I don't spill anything.

 

[IDoSeaDoo]

Yep, that's pretty much what I've had to resort to doing. I just don't get it though. Seems like they shouldn't have been able to design it like this. It's dangerous and hazardous.

 

[snikwad003]

Well at this point they didn't design it you did, on mine I can pump wide open till it stops it's self and then finish slow and I don't get any barfing.