[rbremmer]

I have a 2002 Mercury 115HP 4 stroke motor which slowly looses power after a few minutes to a few hours of running under load, and eventually dies. Normally turning the motor off and on again will bring it back to life and idles fine and powers up fine... for a while (although under power it usually is a little bit rough), then the process repeats. We run the motor at 3000RPM pushing a houseboat. It will run smooth for a while, then it begins to run rough and looses a 100 RPM or so, then slowly the RPM falls off until the motor dies. When it dies, usually the fuel primer bulb has no pressure and sometimes is difficult to get it to pump up. The tank has plenty of fuel in it. I don't see any water in the fuel filter under the cowling. The wierd think is how well it runs if I turn off the key after it dies and restart it.

[bhile]

Check your fuel tank vent to be sure its not partially blocked.