I have a Yamaha ProV150 outboard with an 11 gallon aluminum gas tank. The tank has a plastic pickup tube attached to a brass 90 that threads into the top of the tank. A straight 5/16" barb fitting threads into the 90. A 5/16" line goes to a water separator, then the squeeze ball, then the engine. This setup has been working fine for years. I recently purchased a 9 gallon plastic portable auxillary tank which I fitted with a plastic quick disconnect Yamaha fitting, (has 1 line up prong and the other prong has the holes in it for fuel flow). I removed the barb fitting from the aluminum tank, installed a brass 90 and the same plastic quick disconnect fitting that I'm using on the plastic tank. Both tanks use the same gas line, water separator and squeeze ball. When I'm running on the aluminum tank, the engine will run fine for a quarter to half mile and will begin to run out of fuel, (the squeeze ball gets sucked down like there's no air going into the tank to displace the fuel going out). I was sure it was the vent, but it is completely open and free of debris. I disconnected the vent hose from the tank so that just the fitting was sticking up and the same problem occured. As mentioned above both tanks use the same components, (the red plastic tank works fine but the aluminum tank runs out of gas). Inspected and dissasembled the parts on the aluminum tank (no sediment, debris, pickup tube competely clean). The only thing that changed was installing the Yamaha plastic quick disconnect fittings. Got me tricked. Any suggestions? Thanks
