Mercury outboard troubleshooting no spark

#MERCURY OUTBOARD TROUBLESHOOTING NO SPARK FREE#

A continued low reading may be caused by a bad capacitor. If the readings are now correct, one of the trigger modules is bad. If there is a low reading on one of the terminals, disconnect the white/blue and green/white trigger wires, then retest. (Remember that some DVA adapters are not polarized and will read the same regardless of the polarity). You should read between 170 and 270 volts Positive on terminal Ti and between 170 and 270 volts Negative on terminal T4. Check the DVA voltage on terminals Ti and T4.

Crank the engine with the starter and then stop.

This is caused by a hard to explain problem with the triggering circuit. A blown head gasket on these engines can cause the coils not to fire with the spark plugs installed.

If the coils will not fire with the spark plugs in, check compression with the spark plugs removed from all cylinders.

Connect a spark gap tester to all cylinders and test with the spark plugs in and out.

At no time should you see battery voltage on a kill circuit.

Connect a DC voltmeter from the kill wires to engine ground and turn the ignition switch on and off several times.

If the engine starts and inns, the key-switch or kill circuit is bad.

Disconnect the white and blue kill wires from the CD Module and retest.

Check for loose connections or a bad battery. Running below l2V or over 16 volts will damage the ignition. In this case replace the coil and retry.ДЄfter repairing the engine, check the battery voltage at approximately 3500 RPM, The MAXIMUM allowable voltage reading is 16 volts and the minimum is 12V. A coil that is shorted internally will give a low reading. If the voltage is right, replace the coil with another coil and retest or use a load resister if another coil is not available.

Check DVA voltage on the gray wire going to the coil, it should be approximately 200 volts at cranking.If the CD module fails to fire with this test, then the CD module is usually bad. If it does, then the CD module is usually good and the points (or Preamp) require checking. If the reading is low, disconnect the white/black wire rom the distributor and with the key switch turned on, strike the white/black wire against engine ground. If the reading is high, and fails to move up and down, there is definitely a problem inside the distributor. There should be some fluctuation in the meter reading. Connect a DC voltmeter to the white/black wire (while it is connected to the distributor) and rotate the engine.if not, the problem is likely in the harness, key switch, starter or battery. Check voltage present on the blue wire at cranking.If it fires when you crank the engine over, there is a problem in the distributor cap, rotor button or spark plug wires. Connect a spark gap tester to the high tension lead coming from the ignition coil and set it to approximately 1/2вЂќ.Units using rubber shock mounts require a ground wire fastened from the pack to the engine block. Clean all battery connections and engine grounds.The chart below will assist you as a general guideline: NOTE: The Chrysler CD modules are similar to the OMC CD modules with the exception of wire colors. WARNING!! Battery cable reversal will cause severe damage to the CD module and rectifier.

#MERCURY OUTBOARD TROUBLESHOOTING NO SPARK FREE#

Maintenance free batteries are NOT recommended for this application. Low voltage symptoms are weak fire or erratic firing of cylinders. (Preamps are electronic replacements for points)ДЄ large proportion of the problems with the battery CD units are caused by low battery voltage or bad ground connections. Point Type Ignitions with Amplifiers (Power packs)

Mercury outboard troubleshooting no spark