1978 Johnson 4HP outboards Service Manual, Page 87Get this manual
Y-4 CONT Page 6-1 Change SHIM GAUGE SHIM GAUGE PART #321520 TO PART #315767
P age 4-10 bErratic or no spark from one or two ignition coils go to step 4
ADD PARTSHIM GAUGE (THRUST BEARING) PART #324797
Page 4-16
Page 6-29 PINION DEPTH SHIMMING bRemove thrust washer and bearingPlace shims removed during disassembly on driveshaft shoulderUsing shim gauge (Special Tool #315767), measure clearance between bottom of gauge and pinion gearNOTE
If any spark is present at spark gap checker
during sensor output test, replace power pack(1) If meter reads 0.3 or higher on all sensor leadscheck for shorts to ground(2) If meter reads lower than 0.3 on any sensorcheck for shorts to groundAlso check sensor resistanceIf sensor resistance meets specifications, low meter reading is caused by low engine rpm or weak sensor magnets in flywheel
Page 6-32 SHIFT ROD ADJUSTMENT aThread shift rod into shifter detent until seated, then back off two or more turns until offset faces forward
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