96 ' 115 Merc can idle low and high rpm but can't gain top speed

I am in need of some help. I have a 96 115 merc. I was running up a river yesterday at top speed when it seemed like the engine bogged down to about 30% of max speed and I could hear the RPMs were down as well. Boat idles fine and I can rev up to very high rpms at idle without any problems. If I mannually pump the bulb several times and gun the engine I can reach speeds above the 30% of top speed but it bogs back to about 30% power within about 4 seconds. Engine does not sound like it is missing and is not idling rough at low-high rpm. I did fill the internal tank yesterday so I know the fuel is fresh and there was no ethanol content. I saw a little gas squirt out of the tank vent when it was full so I don't think the vent is clogged. I am thinking this is a fuel/air problem but I am at a loss.

Re: 96 ' 115 Merc can idle low and high rpm but can't gain top speed

Might be time for a fuel pump rebuild as it sounds like it is not keeping up with what the motor needs for fuel. Oldman570