I have a 1971 Evinrude 50 hp outboard. The engine was recently rebuilt. It starts easily and runs okay as long as you pump the primer bulb on the hose every 3 to 5 minutes. I've tried 2 different hoses and tanks, so I don't believe it is related to these items. I've disconnected the line from the fuel pump to the carburetor, when you pump the primer bulb, fuel runs full stream. If the vacuum line is disconnected and the primer bulb is pumped, there is no fuel noticed in the vacuum line, so perhaps the diaphram is okay. The vacuum line does not seem to have any vacuum when the engine is operating, but I'm not sure how much there is supposed to be. The fuel pump has been replaced as well as the vacuum hose, etc. It seems that the problem is no vacuum from the lower crankcase port, but the engine seems to run okay as long as it gets fuel. Any thoughts are greatly appreciated. Thanks
