MERCURY TROUBLESHOOTING

Note: If CD-77 is used for DVA, you will need a good volt/ohm meter. A large portion of the problems with the battery CD units are caused by low battery voltage or bad ground connections. Low voltage symptoms are weak fire or weak erratic firing of cylinders.
WARNING!! BATTERY REVERSAL WILL USUALLY DESTROY BATTERY CDs AND TRIGGERS.

1) Check all battery and qround connections.

2) Dead or no fire until you let off of the key switch:

Disconnect Mercury switch and retest , if the engine fires, replace the mercury switch. Check the voltage on the red and white ignition wires at the CD unit. If the voltage is less than 9½ volts during cranking there is a problem in the battery wires or ignition switch circuit. These units require at least 9½ volts to fire properly. On a 332-2986 switch box, check the voltage on the brown terminal (white / black for 332-4796) where the trigger is hooked up. It requires at least 9V at cranking. DVA check between the white and black wires (black and blue on 332-4796). You should read at least 2%2V at cranking. Connect a jumper wire directly from the battery pos (+) terminal to the red and white ignition wires (the red wire is not needed for CDI units). CAUTION: DO NOT CONNECT THE JUMPER WIRE TO THE WHITE TRIGGER TERMINAL Retest. ATTENTION: In order to kill he engine if it cranks, the jumper wire has to be disconnected and/or choke the engine. If the engine still fails to crank, recheck voltage as above. If low, replace battery and retry. If there is still no fire, disconnect points wire (or trigger wires) and connect the Battery CD tester (511-9701 ), according to the instructions in the manual, and align the rotor with a spark plug wire. Connect a spark gap tester (511-9766) to all spark plug wires and turn the ignition switch on. If the CD unit fires to only one spark plug wire, check points wire (for breaks and shorts) or trigger. If ANY other spark plug wire fires besides the one the rotor is aligned with, the distributor cap and rotor should be replaced. The Battery CD tester will fire the system to approximately 3000 RPM. If the Battery CD tester is not used, see related drawings on next page. If the CD unit fails to fire with this hookup, it is usually bad. Following the instructions included with the Trigger Tester (511-9710), check the trigger to see if it is good or bad.

3) Engine cranks and fires as long as the starter is engaged: This problem usually indicates a bad trigger.

4) Check the ignition coil. An open, cracked or poorly grounded coil can burn out a battery CD.

5) Check the DVA voltage on the primary input wire to the coil using the Fluke meter with the peak reading voltage adapter (511-9773), or CD 77. The reading should be approximately 100 volts or more for OEM CD’s, and 200+ for CDI Electronic units.

6) Inline engines with internal exhaust plate: If engine speeds up when you remove one spark plug wire, the internal exhaust plate is more than likely warped. The following tests can be performed on the bench or on the engine. NOTE: Disconnect the trigger mechanism prior to testing:

7) Engines runs rough on to or bottom two cylinders (4 cylinder engines): Check DVA voltage of the stator between blue wires and to ground. Readings to ground should be fairly equal. If unequal, swap stator leads (blue with blue/white, red with red/white) and see if the problem moves with the stator leads. If it does, replace the stator. Check trigger resistance between #1 & #2, compare to resistance between #3 and #4. The readings should be approximately 850 to 1250W for OEM (950W for CDI & Rapair). For test purposes only, swap trigger leads 1 & 3, and 2 & 4. If the problem moves, replace the trigger. If it does not move, swap coil primary wires, and replace the pack if the problem remains on the same terminals.

8) No fire on one bank (odd or even cylinders on Inline 6 cylinder engines): Check DVA voltage of the stator, checking from each red and blue wire to engine ground. The readings should be approximately 180 volts or more on the blue wires and 30 or more on the red wires. If a DVA meter is not available, swap both sets of the stator wires between the packs. If the problem moves, replace the stator. If the problem stays on the same bank, swap physical location and all connections of the two packs. If the problem stays with one pack, replace the pack. NOTE: If the pack is bad, it is recommended that BOTH packs be replaced if the packs are manufactured by CDI or Rapair. If the packs lose ground, internally or externally, the packs manufactured by other sources usually have severe damage to the bias circuit and have to be replaced as a set. The packs manufactured by CDI and Rapair will withstand loss of ground connection, normally with no damage to the bias circuitry. In most cases you will just lose fire.

9) Intermittent firing on one or more cylinders: Disconnect the white/black wire between the packs on a 6 cylinder and retest. If all cylinders now fire, replace both packs as there is a problem in the bias circuitry. On all others, check for low voltage from the stator and trigger. Disconnect the rectifier and retest. If the problem disappears, replace the rectifier.

10) All cylinders fire but the engine will not crank and run: On 3 and 6 cylinder engines, disconnect white/black wire and check the bias circuit (white/black terminals) resistance to engine ground. Readings should be approximately 15,000W for standard packs and 9600W for racing units. If the readings are correct on the packs, index the flywheel and check timing on all individual cylinders. If the timing varies, replace the packs. On 4 cylinder engines the bias circuit is internal, therefore the only way to verify proper operation of the bias circuit is to index the flywheel and check timing on each cylinder. If the timing is off replace the packs.