Fuel Tank overflow when filling GW Sailfish 272 1998

[Kangasell]

Hi all,
Would someone have an answer about why when I attempt to fill the 150 Gallon tank it continuously overflows and it takes forever to fill. The boat has a breather through the hull on the starboard side just opposite the head area so not sure if this is for fuel or head. It seems like an air blockage. When I removed the deck plates to inspect both tanks, I can see the breather for the aux tank 52 gallons but I can't see the main tank breather anywhere? Where do you think the breather is and how would it work? Is it perhaps in or below the filler cap on the Starboard gunnel?
I have just purchased this vessel and the previous owner can't advise much at all.

 

[DennisG01]

I don't know if you have a stand-a-lone vent fitting or if it's integral to the fill fitting. You might find the answer in your manual, but it shouldn't be too hard to figure out what vents are for what components. Just take a good look at things (start with the head) and it's pretty easy. "Most", but not always, of the time the vent is relatively close to the fill. Physically check the vent and see if it's blocked up. After that, it sounds like you have a dip in the vent line somewhere and that dip has collected fuel. Follow the vent line and check it out.

I'm sure the vent is there - or at least it would be REALLY strange if someone removed it. It's probably just at a different location on the tank - try a mirror and a flashlight - or a snake camera.

 

[Koondog]

Both of my vents are just below the fill locations. I have a 25' Sailfish 1990 model and as I fill each tank I can hear the air whistling out of the vents. One vent for each of the two tanks.

 

[CKJR]

the vents are internal to the fill, there is no external through hull vent at least not on my 1998. When I approach full, the vent spills back into the fuel fill tube.

 

[seasick]

Hi all,
Would someone have an answer about why when I attempt to fill the 150 Gallon tank it continuously overflows and it takes forever to fill. The boat has a breather through the hull on the starboard side just opposite the head area so not sure if this is for fuel or head. It seems like an air blockage. When I removed the deck plates to inspect both tanks, I can see the breather for the aux tank 52 gallons but I can't see the main tank breather anywhere? Where do you think the breather is and how would it work? Is it perhaps in or below the filler cap on the Starboard gunnel?
I have just purchased this vessel and the previous owner can't advise much at all.

The vent line should have a loop in it that allows any fuel or perhaps water to drain back into the tank or out the vent if the vent is not integrated into the fill.
If the original loop got disturbed or as is often the case, a new vent hose was installed but without the proper loop, the hose can develop a pool of fuel when the tank is filled to the top or in the case of an external hull vent, water gets into the vent. The back pressure while filling the tank may not be enough to displace the column of fuel causing the gas nozzle to shut off.
The vent hose could also be blocked by something like an insect nest.
You need to check that the vent hose is clear. That can be a pain to do depending on how the hose is run and what if any play it has.

A second possibility is that the fill hose has a blockage. In that case fuel can't flow as fast as the nozzle is feeding the tank. The hose will backup and the nozzle will auto shut.
Sometimes something gets stuck in the fill like the seal on a bottle of fuel treatment that came off of the bottle. Again, finding the problem is complicated when it is difficult to remove the fill and or vent hose at the tank

 

[Legend]

Had the issue of fuelnot flowing in with a Mako yoears ago. The issue turned out to be an old fuel hose and it was basically collapsing. The vents were fine - good luck