How to test a Johnson Evinrude VRO pump
Using the diagram for reference, install and carefully secure a 10" length of 1/4" clear vinyl hose to the oil inlet on the pump. A few inches from the loose end, measure carefully and mark the hose every 1/2" for a total of 3 inches.
Fill the hose with outboard oil and run the engine to eliminate air from the base of the hose. Shut off the engine, and add or eliminate oil until the level is even with your highest mark.
Start the engine and monitor the pump cycles by using a fuel pressure gauge or by putting light finger pressure on the outlet hose.
Expected Oil Draw Results:
- At 800 RPM: The oil level in the hose should drop 1" in approximately 5 pulses.
- At Full Throttle: The oil level should drop 1" in approximately 3 pulses.
Troubleshooting Variations:
If results vary from above, the pump may be failing. However, check the pulse limiter fitting before replacement.
Disconnect the pulse fitting hose and crank the motor. Is there a strong pulse of air through the fitting?
If results vary from above, the pump may be failing. However, check the pulse limiter fitting before replacement.
Disconnect the pulse fitting hose and crank the motor. Is there a strong pulse of air through the fitting?
- If Yes: The fitting is okay.
- If No: Check compression on the bottom cylinder (which operates the pulse valve). If compression is low, that cylinder needs attention. If compression is okay, replace the fitting and repeat the test.