This is a very common issue for the original predator 212 tanks.
We blow out the guts on that valve on the rear of the tank, put a fuel filter on it with a tiny piece of hose. To do this, Grab the valve with a pair of vice grips and we smashed the guts out with a screwdriver and hammer. And reinstall it.
2nd, larger i.d. fuel line. But with this you need to zip tie the line off of the cylinder jug, to the pull cord side cover. Again zip it away from the motor, TO the pull cord side over.
3rd if you're engine is at an angle, the outlet is on the rear, as in the high side of the tank. Anything under a 1/4 tank won't make it to the hose.
We put a few washers under the front of the tank between the mounting studs. To raise the front of the tank.
I only say all of this because just drilling a cap hole did not work for us. Doing everything you keeps that fuel insurance cheap