1991 Johnson/Evinrude Models "EI" 40 thru 55 Service Manual, Page 66Get this manual
Testing Omitting the tank pressure test may result in returning fuel system to service which could leak liquid or vaporized fuelIgnition of this leakage could result in fire or explosion ill
Whenever fuel tank or line has been serviced or has had parts disassembled, the unit must be tested to ensure that the repaired or reassembled portion will not leak or emit fumes Simply adding fuel to the tank and checking for leakage is not an adequate testas leakage or fumes may occur only when the tank's contents have been pressurizedAs examples, pressurization can occur when the tank is left in sunlightor when the fuel is agitated, as might occur during transport
Tools needed are an air pressure gauge and OMC Fuel Tank Pressure Test Adapter PIN 389945 compressed air supply is also needed