Gas tank Vent question

[Garett]

I'm assuming that on the tank end of the gas tank vent hose there is some sort of check valve, am I right? How can I check to see if it is working properly?

[moorhen]

Why should there be a check valve?

[jtburf]

If the bulb collasps and will not expand untill you open the fill cap your vemnt is not working!

John

[Bullshipper]

Air has to go both ways to fill and empty the tank.
There should be a loop near the vent to help prevent water injestion.
The screens can get crusty and clogged with salt, and sometimes have to be replaced, not cleaned.
Applying two lips and blowing with the gas tank cap off is something you can do when no one is lurking with a video camera. You'll hear a lusty gurgle in the gas tank when she bubbles and blows.

[Garett]

jtburf - 10/4/2004 5:10 PM

open the fill cap !

Dahaaa, I can be so daft at times it even scares me. So no wonder air blew back at me when I blew into the vent hose - the filler cap was on tight. Thanks John

On the weekend I pulled the port side seats and side panels to expose the gas filler tube and the vent hose; I changed the through hull vent - it was looking weathered.

[iawright]

Garrett:

On your Grew do you have the chrome vent that sticks out? I had a lot of trouble with my old Pursuit getting water in the fuel after adding trim tabs. Then I got a couple knocked off in Toronto harbour. I finally had a flush-mount vent with a check-valve installed and it solved all those issues. I believe it was from Taylor or from CC Marine in TO.

[Garett]

iawright,

I reckoned you're referring to this one.


This is basically the same as what I replaced, original only had one vent hole, this has two. When I did get everything pealed away to access the vent hose I noticed the vent hose did not have any loops or such, basically the hose just came out of the vent and then straight down. With that hose configuration I was not adding water into my gas tank of any great quantities - at least the water separator is not picking any up and the engine runs fine.

So with the replacement vent having two vent holes I installed the new vent with one hole going down and the other hole pointing aft - the two holes are 90 degrees to each other. And then when I re-attached the vent hose to the vent I managed to got the vent tube going upwards from the vent and not downwards like it was.

You wouldn't have by chance a picture or link of the vent that you are talking about? I know that my intentions was good when I changed the vent, but that doesn't always mean things work out right.....you know what I mean.

On a lighter note Ian, how are you making out with the fishing this season? Would you be running over to the bluffs in Scarborough or making your way towards Oakville? Are you putting something on the plate?

[moorhen]

Why would you want a check valve on a vent tube? Is it just some sort of a flapper valve to keep out splashes or does it keep air from passing freely. The air needs to be able to go both in and out for filling and emptying the tank and for expansion. Is it a check valve that does not allow gasoline to spill out the tube when overfilling. Please let me know what the deal is with the check valve.

[Bullshipper]

The only check valves or one way valves in the system are found on the fuel lines, not the air vent lines. They are the anti siphon valve and the check valve in the primer bulb.

Good vent systems usually have an open ended 1/2 clam shell protector and come without screens unless the motors are close and spark arrestment is a problem. The also have a length of stainless tubing that runs up hill from the vent before it is looped and plumbed to the hose to prevent any by-splash from getting into the gas. Screens are a bother as the get crusted up with salt.

[Garett]

moorhen,

I've come to the realization that there is no check valve when John mentioned the gas cap.

When I had the hose removed from the vent I blew into it, the air blew back at me from the vent hose. At the time I thought that the system had some sort of check valve because the air blew back at me, but of coarse the deception was the simple fact that I had the gas cap still tightly secured.

After John had posted his thread it dawned on me. When I go home from work that morning I blew into the vent while the gas cap was removed and I could feel the air at the gas filler neck - all was good.

[iawright]

Garrett:

I don't have a picture, sorry, but I've seen those vent covers for sale in Toronto. They're also fitted on the Albe below.

I didn't get to fish much before mid-August because I only picked up the new boat at the end of July. I had to break it in gently. It still doesn't have all the electronics or the kicker installed and working as yet. Hopefully when I return from the Outer Banks in three weeks it will be closer to being "ready to fish". (g)

[Garett]

Ian,

Well I hope you the very best while you are down in the Outer Banks - land every last one of them and regret nothing.