I have a 5HP mariner engine it runs off a external fuel tank, the problem seems to be the engine starts fine when i prime the fuel line but after approx 1-3 mins the fuel seems to not being sucked through and the fuel starts to run back down pipe into the tank? If i prime the fuel back up the engine will run fine all day long but obviously it not ideal to have to keep priming the fuel line every few mins.... Anyone any ideas please 
Cheers...
Cheers...