Engine will start with starter fluid but will not run thereafter. I have cleaned and rebuilt the carb. and replaced the fuel feed hoses but it still does same thing. Primer "bulb" works and holds suction OK if I remove the input feed pipe from the carb. to the bulb and block the input to the bulb - so the one-way valve in the bulb seems OK. I notice that when I prime it using the bulb there is clear fuel in the feed pipe to the carb, but the fuel line from the carb. to the primer "bulb" has bubbles. (After several primes these bubbles actually cause the fuel tank to pressurize!). It seems that air is getting into the fuel somewhere within the carb. as the fuel is clear going in but has bubbles coming out as it moves towards the bulb. Help someone please, I'm mystified! Thanks Dave