2009 Yamaha F40 Outboard Service Manual, Page 357Get this manual
Maintenance 4Remove the oil filler cap aPull out the dipstick and use the oil changer to extract the oil completely
Water inlet cover screw c: Nm (0.1 kgfm, 0.7 ftlb) 5Place the lower unit in water, and then start the engine6Check for water flow at the cooling water pilot holeIf there is no water flow, check the cooling water passage inside the outboard motor
Checking the engine idle speed
1Start the engine and warm it up until the idle speed gets stable at 750850 rmin2Check the engine idle speed using the Yamaha genuine tachometer (on-board meter) or the YDISTo connect and operate the YDIS, see the "YDIS (Ver1.32 or later) Instruction Manual