1997 Johnson Evinrude "EU" 9.9 thru 30 2-Cylinder Service Manual, P/N 507263, Page 72Get this manual
Disassembly
1Remove primer pump housing retaining ring from primer pump2Remove primer plunger from housingDiscard O-rings
Inspection
1Inspect brass plunger shaft for any burrs or scratchesRemove small scratches by polishing the plunger with crocus clothIf the plunger has deep scratches, replace the plunger2Inspect plunger where cross hole intersects inside holeAny burrs around cross hole will accelerate wear of O-ringsRemove any protruding burrs and polish with crocus clothThe check valve under the small nipple on the primer pump housing allows fuel flow out of the pump housing and prevents flow into the housing
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3To inspect for proper check valve function, use squeeze bottle containing alcohol (such as isopropyl rubbing alcohol)Connect clear plastic hose between small nipple and bottle to observe flow of alcoholSqueeze the bottle lightly to force alcohol through the hoseVisually check for flow of alcohol into the housing It is permissible for few drops to be presentThis indicates the check valve is blocking the flow and functioning correctlyIf steady stream of alcohol flows through the small nipple, the check valve is inoperative and the primer pump housing must be replaced