I hooked up a temporary 6 gallon tank and primer bulb with hose to both of my Evinrude 150's and the bulb got really firm and the engines started right up. I thought the anti siphon valve may be the problem but they were not. I can't find a leak any where. The only other components in the fuel path is 3 way valve for main and aux tank and fuel water separator filter. Could someone tell me why when on a 6 gallon temp tank the primer bulb gets rock solid but when on the main and aux tank the bulbs do not firm up. I have also replaced the bulbs with new ones. This problem makes if difficult to start the motors, but not when feed from the temp tank. Thanks for any clues you could provide.