It sounds like the power valve but maybe the fuel isn't passing a blown diaphram but instead either the wrong style gasket was used (there are three styles) or the powervalve isn't tight enough, I've found both in the past... Did the power valve have a small step to locate the gasket? Which style gasket did you use? the hole in the center some are round, some are three sided & some have locator legs... If the valve has the locator step you need the round centered gasket...