CDI Electronics Outboard Ignition Troubleshooting Guide

87 Mercury Troubleshooting Mercury ONLY HAS SPARK AS LONG AS THE STARTER IS ENGAGED: This symptom usually indicates a bad trigger or low voltage. NO SPARK OR INTERMITTENT SPARK ON ONE CYLINDER: 1. Connect a spark gap tester to the high-tension leads coming from the distributor cap and set the gap to approximately 7/16”. (Use of a CD Tester is recommended). 2. Align the rotor with #1 spark plug wire. Disconnect the trigger wires and connect a jumper wire from the brown trigger terminal to the white trigger terminal. 3. Connect another jumper wire to the black trigger terminal turn the ignition switch on. Strike the jumper wire from the black terminal against engine ground – (DO NOT HOLD THE JUMPER AGAINST ENGINE GROUND). Only the #1 spark plug wire should fire. If any other spark plug wire has fire, there is a problem in the distributor cap. 4. Repeat the test for the other cylinders. HIGH SPEED MISS: 1. Check the battery voltage on the red and white terminals of the switch box at high speed, the voltage should be between 12.5V and 16V DC. A reading outside this range will damage the CD module. If the readings are abnormal, perform the voltage drop test described above. 2. Perform a high-speed shutdown and read the spark plugs. Check for water. A crack in the block can cause a high miss at high speed when the water pressure gets high, but a normal shutdown will mask the problem.