Gas filling tube clogged?

[Pfu]

Went to fill one of two tanks over the weekend and my primary kept shutting off like something was blocking the gas fill tube. Opted to move to auxiliary tank and filled fine. Need to go back to marina and see what’s up with main fuel fill line. Any words of wisdom?

 

[seasick]

First If you vent is clogged, the nozzle will shut off. What type of vent do you have; external clamshell type or combo fill/vent fitting?
If external it is common for insects to make a nest in the vent clam shell or if there is a screen in the vent fitting, it may be clogged.
If you use additives to your gas and you do so using the additive bottle, some folks have had blockage due to the cap seal of the additive falling into the fill

 

[Chessie246G]

Much more likely the vent is clogged and not eh fill. the fill is about 2 inch diameter.

 

[seasick]

Much more likely the vent is clogged and not eh fill. the fill is about 2 inch diameter.

That is true but some fuel fill lines have a grate that is supposed to deter gas siphoning. In that case the small seal from an additive bottle can get caught by the grid and partially block the flow. That can increase the back pressure and trip the gas nozzle shutoff.
That said, based on the age of the boat, I would lean towards a venting issue.

 

[DennisG01]

Most likely your vent system... a dip in the vent line that has accumulated gas/water or a clogged hull vent fitting (primarily if you DON'T have an all-in-one fill/vent setup).

 

[Stickbo]

I found after compounding one of my boats that the screen on the vent was blocked after it wouldn't take fuel. Worth a look.

 

[Sardinia306Canyon]

As others already wrote, a clogged filler hose is highly unlikely, it's 95% the vent hose, the vent itself or on newer boats the charcoal canister clogged.

I found after compounding one of my boats that the screen on the vent was blocked after it wouldn't take fuel. Worth a look.

Yep, that is what often happen,
to verify that do a visual inspection or and if accessible disconnect the vent hose from the vent to verify if clogged.

Chris

 

[Keywest1]

Hi to all from Perth Western Australia.
I'm new to this group so please forgive me if I'm not great at getting my question across well.
I have just purchased a 2008 30ft Marlin with twin 250 hp 2021 Yamahas fitted with low hours.
I'm looking at the fuel filler set up and can't work out how the both motors can draw fuel when the tank breathers/vents are inside the fill pipes, and the fill pipes are fitted with an airtight screw down fuel caps.
My understanding is the fuel used when running the motors needs to replace in the fuel tank with air at the same outside air pressure, otherwise a vacuum will be created.
Can anyone tell me how the tanks get the air to allow the fuel to run, as I can not see how it does (and the motors runs so it must drawing air to avoid being a vacuum )
Kind regards

 

[Halfhitch]

Keywest, this link describes how those things work. Some of the newer systems that include the charcoal canisters and such may have caps that are more advanced than those described here.

https://forums.iboats.com/threads/perko-vented-gas-caps-–-how-they-work-and-a-couple-of-tips.769236/

 

[seasick]

Your boat most likely has a combo fill/vent filler fitting. Even though the cap is screwed down tight, there is a valve that opens and lets air into the tank when gas is consumed. Note that the non combo fillers have caps that look the same for the most part so if replacing make sure you get the correct cap

 

[Pfu]

First If you vent is clogged, the nozzle will shut off. What type of vent do you have; external clamshell type or combo fill/vent fitting?
If external it is common for insects to make a nest in the vent clam shell or if there is a screen in the vent fitting, it may be clogged.
If you use additives to your gas and you do so using the additive bottle, some folks have had blockage due to the cap seal of the additive falling into the fill

Combo vent. Have not had chance to get back to boat yet.

i do add additives but super careful to not drop in anything. Never let others do it!

 

[Pfu]

As others already wrote, a clogged filler hose is highly unlikely, it's 95% the vent hose, the vent itself or on newer boats the charcoal canister clogged.


Yep, that is what often happen,
to verify that do a visual inspection or and if accessible disconnect the vent hose from the vent to verify if clogged.

Chris

Steps to disconnect the two? Not a lot of space between the two fill hoses.

 

[Sardinia306Canyon]

I don't know you boat so i can't help you how to disconnect the hose.
There should be a access plate near the vent and behind are the hoses and the nut holding the vent in place.
Inspect there and find a way to disconnect them, and there will be a way.

Old rubber hoses are a total PITA to remove as they get hard as rock and i prefer to cut them on the vent, attach a new hose and pull the new hose with the old one. Sometimes that works, sometimes it turns out a even bigger PITA.
Fuel fill hose are even worst as they have a unnecessary steel wire inside what makes cutting and sliding over another PITA and the steel wire can create sparks.

You may start with disconnecting the vent hose from the fuel tank and blow inside to check for restrictions, using a figher flow compressor would give a better result as blowing does not create a high flow.

Chris

 

[Pfu]

Apologize for the late response. Dad fight cancer and spending time with him.

thanks for the input. Decided to tackle this when I pull in October and use the second take - still 92 gallons - and not going too far with risks. Will post my results at a later date!