2003 Johnson ST 55 HP WRL 2 Stroke Commercial Service Manual, PN 5005483, Page 104Get this manual
FUEL SYSTEM FUEL SYSTEM TESTS
FUEL SYSTEM TESTS&CAUTION
START outboard and run at FULL THROTTLE for at least two minutesMonitor clear vinyl hose for the presence of airThere should be no air or vapor bubbles visible in the clear hoseAir bubbles indicate faulty hose, connection, or fuel tank pick-upRepair, if necessary, before proceedingThe maximum inlet fuel vacuum must not exceed inHg(13.5 kPa) at the fuel inlet of the pump under any operating conditions (IDLE to WOT)A higher vacuum indicates an excessive restriction in the fuel supplyRepair as needed Refer to FUEL SYSTEM REQUIREMENTS in INSTALLATION AND PREDELIVERY sectionIf faulty anti-siphon valve is suspectedcontinue with Anti-Siphon Valve Test
To prevent accidental starting while servicing propeller, twist and remove all spark plug leadsInstall the proper test propeller and put the outboard in suitable test tank
IMPORTANT: To avoid damaging the fittings, push hoses off fittingsDO NOT pullIf pushing will not separate hose from fitting, carefully cut the hose along its length and peel it backStart the outboard and allow it to reach normal operating temperatureStop the outboard