Trouble with kicker...maybe fuel delivery

[Gun Rod Bow]

I have a two year old Mercury 8 hp 4 stroke on my Willie Predator.

It runs like a top when cold and coming off the dock.

When I have been trolling/running at near idle speed for an hour or two, then try to throttle up, it sputters and won't run up. It doesn't die and continues to idle.

I try to pump the bulb then and it is soft, no matter how much I pump it.

It is plumbed straight into the discharge side of the fuel filter.

I replaced plugs and fuel filter and the symptoms are exactly the same.

The big motor will start and run at this time, but the little motor seems starved for fuel after an hour or two at troll speed.

Any ideas?

[Grain of Salt]

my guess...air leak in the system (soft bulb)...check all hose fittings and be sure barbs match fuel line diameter...may need an addition check valve inline and be sure your bulb is tipped beyond 45 degrees (allows check valves to work)...did it work before?

[Starfish]

If the bulb won't pump up, it sounds like either your fuel line/bulb is bad and should be replaced, or you have an air leak at the fuel filter connection.