Trouble shooting no spark from coil when using distributor trigger

[chipperstrauss]

I recently acquired a 1972 Mercury 650 3 cyl in pieces but attached to a 1970 Larson Lapline and on a trailer. A previous owner installed a CDI Electronics CDI switch box and coil. I replaced the coil and can get a spark manually by following the CDI Electronics troubleshooting instructions for the CDI switch box (P/N 114-4796). When I connect the switch box to the trigger wires from the distributor, I loose the spark from the coil. I just spoke to CDI tech support (who have been very helpful). I asked for voltage spex for the wires coming from the switch box which connect to the trigger wires. They said the white/black wire should show >= 9 volts and, using a DVA, the black to blue should show >= 3 volts at cranking speed. I went back to suspecting the switch box because a second distributor, also preowned, showed the same symptom. I have a third distributor which I still need to test. My engine doesn't have a tilt switch. I have disconnected the rectifier and starter solenoid and will replace with new aftermarket components. I have a fully charged battery to connect to the switch box. I use jumper cables to power the starter motor. I will test the voltages on the CDI box this morning and update this posting. In the meantime, any thoughts on what I am missing or what direction I should go. Is the trigger a common or rare failure?
I await your advice,
Chipper

 

[racerone]

There are better examples of Mercury engineering than this 3 cylinder 650.-----Keep your eyes open for a better motor.

 

[chipperstrauss]

Put in a little different way...
I would like help with testing the trigger on my 650 3 cyl. I can't seem to locate any spex (like an ohms resistance value) to tell me if the trigger is good. The only way one can tell is if it causes the coil to spark. I have a CDI Electronics aftermarket switch box. I can manually spark the coil following the instructions for the switch box. When I hook up the trigger to the switch box and crank the engine, no spark from the coil. I now have 3 pre owned distributors. One of the triggers should work. It seems unlikely that all 3 triggers would be bad. It would be terrific if I could test the trigger prior to rebuilding the distributor with a different trigger. The wires themselves visually look good and are pliable. I could test the resistance of the wires but that would require using a needle probe because the distributor ends are molded in the housing.
Should the trigger fire by just spinning the gear by hand to simulate cranking? This would imply a rotation speed requirement for the trigger to work. It seems that if there is power going to the trigger, which I have verified, turning the distributor by hand should cause the trigger to send the correct signal to the switch. I have no safety tilt switch. The rectifier is not hooked up to the stater. I am trying to isolate the problem by taking as much out of the equation as possible. I did get a DVA spec from technical support of CDI Electronics which I have yet to do because it requires putting almost everything back together again. But, I can spark the coil which usually means the switch box is good.
I was hoping to get my boat on the water by July 4th to watch the fireworks. But, barring a miracle, that is not going to happen.
I can't give up on this 3 cyl 650. I can purchase a trigger housing for $225. I just would like to know if I do that the engine will work. The CDI Electronics switch does spark. When I a trigger to spark the coil, I can move on to the distributor cap, wires, and spark plugs... all of which look good to the eye.
One person said the triggers are susceptible to failure by engine vibration. Does that make sense?

 

[chipperstrauss]

Here's an update.
After trying three preowned triggers, I bought one from SeaWay Marine (Francisco there has been very helpful). I installed the new trigger and wired up the new rectifier, starter solenoid, solenoid/starter cable. I put the lower end in a garbage can full of water; spritzed a little starter fluid in each carburetor and wah lah; it fired up. However, no water stream out the back. I took the 10" hose off and tried to blow through it with no luck. A bug had made a home. A coat hanger cleaned that up and the water pump proved to be working. The carbs seem ok. it is idling a little fast.

I wanted to test the stator while the engine was running. There is only 82 mV out the rectifier. That's about 13 volts short of what is needed. So, I found a new old stock stator (again at SeaWay Marine). It should arrive early next week to be installed and tested,