2004 SR Johnson 2-stroke 40, 50HP Service Manual, Page 146Get this manual
OMS Pump Trouble Check Chart NO
External fuel leakJ
Connect gearcase pressure tester to OMS pulse hose fittingSet pressure at 15 psi (103.4 kPa)Air on left of air motor diaphragm is at 15 psi (103.4 kPa), air on right is trapped by the vacuum valveAir motor piston moves slightly right until force of spring and air pressure on the right equal force of pressure on the leftI Does the pump hold pressure?
YES NOSlowly pump gearcase testerInspect for escaping airDoes the pump click several times with each stroke of tester?
Install fuel chamber a-ring, fuel outlet fitting a-ring, fuel inlet fitting a-ring, or inlet housing assembly
Hold pump in normal running positionCover fuel outletRapidly remove pressure hose from pulse fittingDid pump click?
Is air leaking from fuel outlet?
Air motor is cracked or leaking or vacuum port a-ring is leakingREPAIR LEAK, REPLACE VACUUM PORT O-RING OR REPLACE AIR MOTOR COVER
YES NO Shaft seal is leakingREPLACE FUEL PUMP
YESWait secondsUncover fuel outlet Did pump click?
Fuel piston diaphragm or flapper valve is leakingInstall fuel diaphragm kitYES NO