1990 Johnson Evinrude "ES" 40 thru 55, P/N 507872, Page 76Get this manual
Boat Fuel System Recommendations Purpose This information is provided to assist you in evaluating boat's permanently installed fuel system Large 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 installed ABYC's Standard H-24 and ICOMIA's Standard No17 are accepted as industry standards and should be referred to for additional information
INote permanently installed fuel system pumping capacity with excessive restrictions could exceed the VRO unit's
and cause poor engine performance or serious powerhead damageTo evaluate the restrictiveness of permanently installed fuel system, refer to Testing Fuel System, this SectionRecommendations 1Fuel Tank Pickup Tubeminimum inside diameter of 38 in(9,5 mm) is required for V6 and larger engines in(9,5 mm) is preferred for V4 and smaller engines, while minimum of 516 in(7 ,9 mm) is requiredTwo separate pickup tubes are required for dual engine installation