I have a 1977 Johnson 75 Stinger. It cranks and runs great. If I stop for 30 minutes to an hour to fish or troll, when I get ready to crank up again the engine has lost its prime. I have to pump the bulb about 3 times and it cranks right up. Why am I losing the prime? The boat has a 20 gal. built in tank. I put a new fuel line and filter on but did not help. I have now installed a anti-syphon valve at the tank. I've not had a chance to see if that helps.
Has anyone had a problem like this?