1998 Johnson Evinrude EC 50 thru 70 HP 3-Cylinder Service Manual, Page 70Get this manual
5If your reading is greater than inHg, you must test each boat fuel system component for excessive restriction before continuingRefer to Boat Fuel System Recommendations, this section, for component descriptions [[] 6If you suspect the anti-siphon valve, perform these tests Remove anti-siphon valve from fuel tank and install adapters and appropriate size 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 are different7If your reading is less than inHg and air bubbles are visible in the clear hose, check entire boat fuel system for air leaksRepair leaking connection Transparent Hose Adapters Tank End Anti-Siphon Valve Engine End