bad switchbox or trigger on mercury 65hp 73-75 3clyinder.

[jldsomething]

can anyone tell me how to tell the difference if my switchbox is bad or trigger?
i have no spark at all three plugs
its not coil i have changed that.
im getting power to switch box
wires are all fine i have checked.

its a 65 hp mercury year is 73-75 not sure. serial number starts with a 405.
i have tested all the manual will tell me and am at a loss i do not have dva tester only a automotive ohm tester.
most things i have read point to switch box because none of the 3 plugs are firing at all.
also the problem is intermediate it was starting and running then took a lake and wouldn't start back up then brought it home and it would start and went out the next day and it would not start.

i have tested switch box while trying to start and one white wire as hot as crankin over but no power going to the coil or other wire on the distributor.

 

[CharlieB]

Re: bad switchbox or trigger on mercury 65hp 73-75 3clyinder.

On the switchbox there is a black wire with a thin yellow trace, this is the 'ground-to-kill' wire, disconnect it and check for spark. Careful, if you start the motor you will NOT be able to turn it off without running it out of fuel.

If you now have spark, start checking your ignition switch, it could be going bad, grounding out and killing spark. Use your Ohm's meter and test that black w/yellow wire at the harness for ground, it should only read when the switch is OFF. Turn the switch on and off several times, if it shows ground even part of the time when turned ON, suspect you may need a new switch assy.

 

[Faztbullet]

Re: bad switchbox or trigger on mercury 65hp 73-75 3clyinder.

Here are links to testing an installing replacement parts.... Sounds as if trigger went bad.
www.cdielectronics.com/InstallSheet/114-4796.pdf
www.cdielectronics.com/InstallSheet/511-9710.pdf

 

[jldsomething]

Re: bad switchbox or trigger on mercury 65hp 73-75 3clyinder.

well i dont have a tester to do the trigger test only a ohms meter. i was wondering if i could jump the white wire wich has power when the key switch is on to the blue wire from the trigger. if i use a jumper wire on the switch box to do this and put a sparkplug tester on it and and turn the engine over this should force the coil to spark if the switch box is good right? iv tested the black wire to a ground with a ohm meter and got 0 so im guessing the ground is good. i think the trigger has just completely went out. when i crank the engine over and use a tester light the white wire is constantly hot but even with the engine cranking the blue will not light up. my trigger wires are white. blue. and black.

 

[Faztbullet]

Re: bad switchbox or trigger on mercury 65hp 73-75 3clyinder.

No olny test like the test below or you may damage switchbox....
No Spark:
1. Connect a spark gap tester to the spark plug wires and check for fire on all cylinders. If some cylinders fire and
not others, the problem is likely in the distributor cap, rotor button or spark plug wires. Notice: If the unit only fires
when you let off of the key switch, the trigger is usually the problem.
2. Disconnect the mercury tilt switch and retest. If the ignition works properly, replace the mercury switch.
3. Connect a spark gap tester to the high tension lead coming from the ignition coil and set it to approximately 7/16".
If you have spark when you crank the engine over, there is a problem in the distributor cap, rotor button or spark
plug wires. Notice: If the unit only have spark when you let off of the key switch, the trigger is usually the problem.
4. Check voltage present on the white wire at cranking. It MUST be at least 9? volts. If not, check the harness, key
switch, starter or battery. (Remember to check polarity).
5. Check the voltage present on the white/black wire at cranking. It MUST be at least 9 volts. If the voltage is low on
this wire (but is correct on the white wire form the harness), the problem is likely in the pack.
6. Check DVA voltage on the green wire going to the coil. It should be approximately 200 volts at cranking.
7. Disconnect the blue, black and white/black trigger wires and connect a jumper wire from the white/black wire to
the black wire. Connect another jumper to the blue wire and (with the key switch turned on) strike the jumper
against engine ground. The unit should spark each time. If it does, the CD module is usually good

 

[jldsomething]

Re: bad switchbox or trigger on mercury 65hp 73-75 3clyinder.

i did the test and had a spark so im going to go with trigger on this one now i just got to find a affordable distributor or trigger for it thanks for help.

 

[CharlieB]

Re: bad switchbox or trigger on mercury 65hp 73-75 3clyinder.

Disregard my earlier post, I missed that yours is a distributor motor.

CDIElectronics is making distributors and triggers.

 

[jldsomething]

Re: bad switchbox or trigger on mercury 65hp 73-75 3clyinder.

could there be a problem with my shifter or key? what if i jumped the two small termenals on the starter solenoid ?

 

[Faztbullet]

Re: bad switchbox or trigger on mercury 65hp 73-75 3clyinder.

could there be a problem with my shifter or key?

If you got 12volts on white wire...no.