1987 Johnson/Evinrude CU Outboards 35A thru 55 Service Manual, Page 90Get this manual
Fuel Pump Servicing Before replacing suspect fuel pump, remove and clean the fuel filter and install new filter elementAlso remove the fuel line from the fuel tank and blow through all passages and lines with low-pressure, compressed air to be sure they are openThis may be the cause of inadequate fuel delivery, and if so, would eliminate unnecessary replacement of the fuel pumpIf this procedure does not correct the trouble, fuel pump is probably malfunctioning and should be replacedinstall new filter element, remove the screw the fuel pump cover to the fuel pumpWhen installing the filter elementplace the lip of the element toward the gasket Install the fuel pump cover and tighten the screw securelyTesting Fuel Pump Conduct this test on the motor in test tank or on the boatBefore testing, loosen fuel tank gas cap momentarily to release any pressure that may have built upFuel tank must not be more than 24 in(61 cm) below fuel pumprJl1 Remove carburetor to fuel pump hoseConnect fuel pressure gauge (obtain locally) between the carburetor and fuel pump2Start motor and observe gaugePump pressures should read as below