1993 Johnson Evinrude "ET" 40 thru 55 Service Manual, P/N 508283, Page 81Get this manual
5If your reading exceeds inHg, you must test each boat fuel system component for excessive restriction before continuingRefer to Boat Fuel System Recommendations, this section, for component descriptions6If you suspect the anti-siphon valve, perform these tests: Remove anti-siphon valve from fuel tank, and install adaptors and clear hose as shown Fill clear hose with water until "X" dimension is 20 in(500 mm)Water must not run through valve Increase water level until "X" dimension is 25 in(630 mm)Water must begin to run through valve before reaching 25 in(630 mm) Replace the anti -siphon valve if your test results vary7If your reading is less than inHg and air bubbles are visible in the clear hose, check entire boat fuel system for air leaksRemember, an air leak into fuel supply system might not create visible fuel leak8If your reading is less than inHg and no bubbles are visible, move the clear hose to the output side of the in-line fuel filter Start engine and run it at full throttle If bubbles appear, test in-line fuel filter If no bubbles appear, go to Step 99If no bubbles appeared in Step 8, remove the clear hose and install 0-15 PSI (0-103 kPa) fuel pressure gauge between pump and carburetors10Start engine and run it at 800 RPM, in gearAfter fuel pressure stabilizes, the pressure gauge must not indicate less than PSI (21 kPa) when held level with VRO hose fitting If pressure is less than PSI (21 kPa), test pulse limiter and crankcase fittingRefer Component Servicing, this section If pulse limiter and crankcase fitting are good and pressure is less than PSI (21 kPa), replace pump Transparent Hose Adaptors Tank End Anti-Siphon Valve Engine End