How much pressure in the tank?

S

serpa4

New member
In my 2018 Venture, when I unscrew the fuel cap, it is under a lot of pressure. I went last week to fill for the 1st time since purchase. The tank was 100% empty since I had to drain it to pull the tank and fix trim tab motor.
Anyways...
When I put the nozzle in the tank, it within seconds started backing up and blowing fuel badly out the filler neck. I tried again and after a few seconds, same thing, fuel blowing out the filler neck and all over me and the boat under pressure. A lot of fuel. I did not have more than say 3 gallons or so in the empty tank.
I had to pull back the vapor collections pollution boot on the pump nozzle to fill the tank slowly.
I did not hear or feel any air come out the vent on the side of the tank either. I checked and did not hear/feel air.
 
Sounds like your vent line is kinked to the point of closing, or is otherwise blocked. If you can view the hose, it likely has a loop in it, and that may be collapsed down and preventing the passing of air. Also check the vent outlet by probing into it with a thin wire to assure some insect has not plugged the end with debris.

Greg
 
Mud dabbers are a common obstruction in the fuel tank vent. Be sure that the fine screen over the vent is clean. Also a loop which collects fluid will prevent vapors, as will the the vapor filter in newest ventilation system.

There can also be a bend or kink in the fuel filling line. See about the vent first.
 
T.R. Bauer":v13zktw6 said:
You should not have pressure in your boat tank as it is directed directly into the atmosphere.
Click to expand...

In Alaska it still is, in a 2018 boat in lower 48 america might have epa rules on venting/vapor recovery. Or he has some blocked/KINKED vent /fill hose??? :mrgreen: :thup :thup
 
T.R. Bauer":2dcay3sx said:
You should not have pressure in your boat tank as it is directed directly into the atmosphere.
Click to expand...

In Alaska it still is, in a 2018 boat in lower 48 america might have epa rules on venting/vapor recovery. Or he has some blocked/KINKED vent /fill hose??? :mrgreen: :thup :thup
 
It can be surprising how much gas expands in a tank on a hot day. I cannot fill my boat(non Cdory) on the trailer - then launch if I am just parking it in a slip for the day. Because of the angle of boat on trailer V/S in the water - when the sun hits it on a hot afternoon the gas will start pushing out the vent(VOPR type). When I used to fill for winter storage it would also start leaking out on the first hot day in spring. I now just pump and polish what fuel is left over the winter.

We have had lots of the mud dabbers Bob mentioned around our place.

Rob
 
Robert H. Wilkinson":dyq7jdg9 said:
Your boats tank should never be pressurized. Check the vent and line is free of obstructions. If it is the VOPR type check the cap and line.

Rob
Click to expand...

I think I have that valve in my fuel cap. The tank vent line goes under the rail and attaches next to the filler hose and inside the filler neck is what looks like a hole to vent under the cap.
Other info:
I have a owner's manual for a E-Valve Model ICM-115P
Evaporative emission control for gasoline boat fuel systems. it goes in the vent line between tank and vent on the side of the boat according to the manual. This large silver box is not on my boat. Maybe it used to have one or two.
Also, in both battery boxes, port/starboard, there is a through hole and barb that is empty. One barb is bare the side the barb has a line on it but is only like 2 feet long and laying loose end in the battery box. I thought it was a vent for the battery box maybe. Now, maybe not.

I'm 90% sure my fuel vent line goes from the tank barb to the filler neck.
How do these vent? Maybe it doesn't and that is not correct.
 
What do you recommend?
Take the vent line off the fuel filler and run it to the barb in the side of the boat in the battery box?

How does the vent under the filler cap actually vent? Maybe at a certain pressure, it somehow opens. It does hold ALOT of pressure though.

If I pull it off the filler neck...I'll have to cut it off. Its on tight. Plug the 1" I leave hanging off the filler neck.
 
http://www.c-brats.com/modules.php?set_ ... _photo.php

This is a picture of my VOPR style cap. The previous pic in my album shows the filler neck. The black plastic piece with holes is how it vents. You can remove it to see how it works. It is designed to allow air in as gas is used and allow pressure out when temp rises. There is no free air movement as with the open style vent.

Is it possible somebody has replaced the cap with a non VOPR style? You can also remove the black plastic part to make sure the holes are not clogged. The cap has an O ring which seals it to filler neck.

Rob
 
serpa4":2t9z8c5r said:
I'm 90% sure my fuel vent line goes from the tank barb to the filler neck.
How do these vent? Maybe it doesn't and that is not correct.
Click to expand...

This is correct - it connects the air at the top of the tank to the top of the filler neck where it vents through the VOPR cap. To work it must have this style of cap and its small vent holes must not be clogged.

Rob
 
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