1991 Johnson/Evinrude Models "EI" 40 thru 55 Service Manual, Page 78Get 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
INote permanently ;nstalled 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 Section Recommendations 1Fuel Tank Pickup Tubeminimum inside diameter of in(9,5 mm) is required for V6 and larger engines38 in(9,5 mm) is preferred for V4 and smaller engines, while minimum of 016 in(7,9 mm) is requiredTwo separate pickup tubes are required for dual engine installation