CDI Electronics Outboard Ignition Troubleshooting Guide

93 Mercury Troubleshooting Mercury Two Cylinder Engines 1970-1971 Model 400 (With the 332-4172 Switch Box) NO SPARK ON ANY CYLINDER: 1. Disconnect the Orange (or Salmon) stop wire AT THE SWITCH BOX and retest. If the engine’s ignition now has spark, the stop circuit has a fault. Check the key switch, harness and shift switch. 2. Check the stator and trigger resistance and DVA output: WIRE READ TO OEM OHMS CDI OHMS DVA (Connected) DVA (Disconnected) Blue Engine GND 3200-3800 2200-2600 180-400 V 180-400 V (*) Red (or White) Engine GND 45-55 45-55 25-100 V 25-100 V (*) Brown Engine GND N/A N/A 1.0 V + N/A (*) This reading can be used to determine if a stator or pack has a problem. For instance, if you have no s park on any cylinder and the stator’s DVA reading is low – disconnect the stator wires and recheck the DVA output. If the reading stays low – the stator is bad. If the reading is now within spec – the pack is bad. ENGINE HAS SPARK BUT WILL NOT RUN: 1. Index the flywheel and check the timing. If it is out, check the flywheel key. 2. If the timing is off and the flywheel key is ok, replace the trigger. NO SPARK ON ONE CYLINDER: If one cylinder is firing good and one is not, the problem is going to be either in the distributor cap or spark plug wire. Two Cylinder Engines 1974-1985 (With 114-4911/ 3 32-4911/332-4733 Switch Box) NO SPARK ON ANY CYLINDER: 1. Disconnect the Orange (or Black/Yellow) stop wire AT THE SWITCH BOX and retest. If the engine’s ignition now has spark, the stop circuit has a fault. Check the key switch, harness and shift switch. 2. Disconnect the Yellow wires from the stator to the rectifier and retest. If the engine sparks, replace the rectifier. 3. Check the cranking RPM. A low cranking speed may not allow the system to spark properly. This can be caused by a weak battery, dragging starter, bad battery cables or a mechanical problem inside the engine. 4. Inspect and clean all engine and ignition ground connections. 5. Check the stator and trigger resistance and DVA output: WIRE READ TO OEM RESISTANCE CDI RESISTANCE DVA (Connected) DVA (Disconnected) Blue White 6000-7400 (a) 2000-2500 (a) 180-400 V 180-400 V (*) Blue Engine GND 5200-7000 (b) 2200-2500 (b) 180-400 V 180-400 V (*) Red Blue 185-205 (a) 45-55 (a) 25-100 V 25-100 V (*) Red Engine GND 180-340 (b) 45-55 (b) 25-100 V 25-100 V (*) Brown White (or Brown) 800-1000 (a) 800-1000 (a) 0.5 V + 0.5 V + (#) Brown White (or Brown) 140-160 (b) 140-160 (b) 0.5 V + 0.5 V + (#) (*) This reading can be used to determine if a stator or pack has a problem. For instance, if you have no spark on any cylinder and the stator’s DVA reading is low – disconnect the stator wires and recheck the DVA output. If the reading stays low – the stator is bad. If the reading is now within spec – the pack is bad. (#) This reading can be used to determine if a pack has a problem in the triggering circuit. For instance, if you have no spark on one cylinder and the trigger’s DVA reading for that cylinder is low – disconnect the trigger wires and recheck the DVA output. If the reading stays low – the trigger is bad. If the reading is now within spec – the pack is bad. (a) 1973-1974 (b) 1976-1978 (w/ full ring stator CDI part# 174-5255) 6. Check the center hub triggering magnet in the flywheel. A loose magnet can cause this problem. 7. Check the triggering and charge coil flywheel magnets for cracked, broken and loose magnets. ENGINE HAS SPARK BUT WILL NOT RUN: 1. Index the flywheel and check the timing. If it is out by 180 degrees, swap the trigger wires to the switch box. 2. If the timing is off by any other degree, check the flywheel key.