2001 Edition Yamaha F225A and LF225A Outboards Service Manual, Page 58Get this manual
Periodic checks and adjustments
Measuring the fuel pressure (high-pressure fuel line)
1Remove the cap 12Install the fuel pressure gauge onto the pressure check valveNOTE: Be sure not to spill any fuel when removing the fuel filter cup
Power unit
Fuel pressure gauge: YB-06766 3Turn the engine start switch to ON, and then measure the fuel pressureNOTE: After the engine start switch is turned to ON, the fuel pressure will decrease graduallyFuel pressure: 310 kPa (3.1 kgfcm2, 44 psi) 4Start the engine and warm it up for minutes, and then measure the fuel pressureNOTE: The pressure regulator can be checked since the fuel pressure (310 kPa [3.1 kgcm2, 44 psi]), from when the engine switch is turned to ON, decreases when the engine is idlingFuel pressure: 270 kPa (2.7 kgfcm2, 38 psi)