25hp 4stroke merc won't hit top rpm

Sugo

Petty Officer 2nd Class
Joined
Nov 11, 2008
Messages
160
This motor in new and I assum it is over pitched as the rpm are fine in netrul, but under load it will only hit 1/3 of the rpm it should. I checked the linkage and it is working correctly. Is there anything else I can check. The fuel pump is working fine and the fuel rail is clean, could it be the electric pump assembly in the fuel rail. How can I test it?
 
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