Trouble Filling my Tank

Forgive me if this thread is in the wrong category, So i have issues with filling my tank. The tank was installed by the previous owner and the boat was sitting for a year and most of the time it was previously owned. I've been using it frequently this last month and when i try to fill the tank with diesel, the fuel doesnt like to go into the tank. It takes a long time for me to fill because while filling it acts like it is full, the fuel with float up in the filler neck and takes a long time to go down. The first time this happened the vent was cut into and i blew air threw it and Fueling began to go smooth again but that was a while ago (may). Lately(yesterday), i can hear the vent bubbling but the fuel does not want to go down. It makes it difficult to know how much the tank needs when you dont have a fuel gage and you dont know 100% what the fuel consumption is. The hose that is connecting the filler to the tank is pretty long and comes down in a "U" shape but i didnt think it would be this difficult.

any suggestions? or cut the filler hose shorter and it will solve the issue?

the fill pipe has a U-shaped section similar to a trap on a sink drain? I would suspect possibly both undersized/clogged fuel vent line and based on your description of the fill pipe line, I suspect the drop down/u-shaped area would be part of the problem. I'd cut the fill line to make as straight a run as possible with no low spots and also double check the vent line is cleared out. What size is your fill pipe line and what size is your vent line?

I think Woodsong is right on the money. You have a P trap going on there.

With a vent the fuel line can't form a vacuum like a house toilet does. So the fuel just backs up. I think the vent is bubbling because it is doing what it is supposed to do.What little fuel does go down the head space is being vented.

With that U in there the fuel will only go in as fast as gravity will allow.

Cut it and re-run it.

Sd

Make sure the vent hose does not have a low spot it needs to slope from the fitting to the tank A low spot will hold fuel and effectly plug the vent When you blew into it it cleared the fuel out of the hose

Blowing into the vent line does not always clear the obstruction(s). I've been bothered by spiders some this year; they love those vent fitting holes. My suspect would be a clogged vent line

Not all hose between the deck fitting and tank is suitable for fuel.

Even great fuel rated hose dies , and gets smaller in diameter as it comes apart internally.

I would replace the fill line between the deck fill and the tank with new fuel rated hose.

FF

motion30 said:

Make sure the vent hose does not have a low spot it needs to slope from the fitting to the tank A low spot will hold fuel and effectly plug the vent When you blew into it it cleared the fuel out of the hose

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This is what I would suspect from the OP's description.

The vent must run uphill from the tank to the opening on the hull with no dips. Sometimes an installer will put an upward loop near the hull fitting to keep water out. That's OK, but no downward loops.