1997 Johnson Evinrude "EU" 40 thru 55 2-Cylinder Service Manual, P/N 507265, Page 79Get this manual
5If your reading exceeds inches Hg, you must test each boat fuel system component for excessive restriction before continuingRefer to Boat Fuel System Recommendations, this section, for component descriptions "'-l
6If you suspect the anti-siphon valve, perform these tests: Remove anti -siphon valve from fuel tank, and install adapters 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 vary
Transparent Hose Adapters Tank End Anti-Siphon Valve Engine End