I have the same issue on my 97 formula no matter how slow I pump it still comes out the vent, and too much for one of those stick on recovery tanks. This is a real pain in the a$$.

I has that problem on my Liberator no check valve on the vent line and it was 10' long with a low point in the middle, had to blow the gas out of it, also had a fuel pressure issue because of this(the reason I found it) lost all types of high end boat woulkd surge then slow down on it's own

Make sure the vent screen is clean sometimes it from waxes the boat it gets in the little holes.

If I missed this in a post, sorry... but that happened to me and the sending unit in the tank was bad. Expected to put 90 gal into a 120 gal tank (the first time) and it only took 35.
Then started spitting.
In the end it was full. The gauge reading was bad.

Always read just over a quarter tank.

I have a new theory...on the trailer, boat sits level and fueling is no problem. Sitting in the water, the weight of the motor, transmission and TRS assembly causes the boat to "squat". The fuel filler and vent connections are at the extreme aft end of the tank.

Is it possible, due to this extreme angle, that the tank won't fill as all the gas is settling toward the back of the tank?

D. Ocean
Pompano Beach, FLA

The vent probably is clogged, Try low pressure [10-15lbs.] air thru vent.

In which direction? I removed the vent hose from the vent thru-hull and blew. There was some resistance and gas came shooting back up. Could the tank be full?

D. Ocean
Pompano Beach, FLA

If the vent hose lays lower than the tank at any point or even lays on top of the tank lower than the vent fitting on the top of the tank the hose can trap fuel in it. If fuel is trapped in the hose it will not let air past it. Make sure the hose is higher than the tank the full travel so any fuel can run downhill back into the tank. This seems to be a big problem on the new boats with the vent in the fuel fill.

Yep. Initially, my vent hose WAS sagging. I re-routed and the problem still exists. I'm just gonna remove the sender and see how much gas is in there.

Thanks again,

D. Ocean
Pompano Beach, FLA

Danny O, My guess the tank's FULL !! DB.