Mercury Mariner 4 and 5HP 4-Stroke Outboards Service Shop Manual 1999, Page 52Get this manual
IGNITION SYSTEM
cPOWER TESTOPTIONAL
IMPORTANT: model9BOO Merc-o-Ironic Magnelo Analyzer (91 -76032) with coil selector switch set onCOlmust be used for test thru E1Connect magneto analyzer test leads to ignition coil
aBlack Analyzer Test LeadsConnected to Ignition Coil Ground b- Red Analyzer Test LeadConnected to Spade Connector of Ignition Coil c- Large Red Analyzer Test LeadConnected to High Tension Spark Plug Lead (Wire Spring Inside Spark Plug Boot) 2Turn "Hi-Lo" current control knob all the way left past "Lo" position3Set analyzer to position "Coil Power Test 4Slowly turn current control knob clockwise whi le noting current value on scale 15When current value reaches 1.7 to 21 amperes, stop turning current control knob and note mm spark gap; it should be firing steadily6If spark is faint, intermittent or no spark occu rs at 21 amperes, replace ignition coil