1993 Johnson Evinrude "ET" 60 thru 70 Service Manual, P/N 508284, Page 58Get this manual
Boat Fuel System Recommendations Purpose This information is provided to assist you in evaluating boat's permanently installed fuel systemLarge outboards require boat fuel system that has high fuel flow rate and low pressure drop across the entire systemIt is very important that all boat fuel system components are of the correct capacity and that they are properly installedABYC's Standard H-24 and ICOMIA's Standard No17 are accepted as industry standards and should be referred to for additional information
permanently installed fuel system with excessive restrictions could exceed the VRO unit's pumping capacity and cause poor engine performance or serious powerhead damage
To evaluate the restrictiveness of permanently installed fuel system, refer to Testing Fuel System, this SectionRecommendations 1Fuel Tank Pickup Tubeminimum inside diameter of 3fs in(9,5 mm) is required for V6 and larger enginesA minimum of 016 in (7,9 mm) is required for V4 and smaller engines, but 3fs in (9,5 mm) inside diameter is preferredTwo separate pickup tubes are required for dual engine installation