Honda BF15D, intermittent can't re-start, primer bulb only 80% hard after many squeeze

[Honda_boy]

The engine can start from cold crank smoothly in the morning. I turned it off for 5 minutes in the middle of lake. When I wanted to continue cruising, it can't be started for no reason. I noticed that the primer bulb can only be squeeze up to 80% hard, not fully hard as I firstly prime. We rested for around 2 hours in the middle of lake, then everything be fine again. Such intermittent starting failure happened three times in the last week. By the way, the fuel line, primer bulb, fuel filter are all newly replaced. The engine is 2003 BF15D with carburetor. Can anyone shed lights on this issue?

 

[MattFL]

Is this a new problem, or has it always been like this?

Next time it wont' start, try starting it with the throttle open 1/4-1/2, just be ready to pull it back as soon as it starts. Hot carbureted 4-strokes often start better when giving them a little throttle.

 

[Honda_boy]

it is a new problem found last week, but it happened 3 times since then.

 

[MattFL]

If it starts with a little throttle then most likely it's flooded, that will give you a starting point for debugging it. Maybe a sticking or leaky float valve, etc.. If a little throttle doesn't help, then next is check for spark when it won't start.