2009 Yamaha F40 Outboard Service Manual, Page 144Get this manual
Fuel system 2Disconnect the quick connectorSee "Disconnecting the quick connector" (64)
3Connect the special service toolsSee "Measuring the fuel pressure" (6-4) step and step 44Disconnect the pressure regulator hose a, and then connect the special service tool to the pressure regulator c
Fuel pressure gauge b: YB-06766 5Turn the engine start switch to "ON," and then measure the fuel pressure within secondsFuel pressure (reference data): 280.0 kPa (2.80 kgfcm2, 40.6 psi)