86' 35 hp Merc Lost Spark

[aMeyers11]

Hi everyone. So I'm going to start with some background info here. So I got the motor with the flywheel installed with the magnets off becuase they fell off. I planned to epoxy them back on but dropped one and broke one. So I bought a new one and installed it. And it was somewhat successful in that I got spark on both cylinders. I went to test the motor and found that it would only sputter snd run rough for no more than 5 seconds. I tried to get it started many times taking breaks not to overheat the starter but each time normally it would only sputter for a couple seconds. And then towards when I began to give up I found that it wouldnt even pop, at all. So I put it away. I thought it was a carb issue. I adjusted the idle screw and tried again today. Well still no popping or sputtering what sk ever. So I out the spark tester on and found that neither cylinder has spark now! I know I'm going to need to remove the fkywheel to diagnose, but I just dont get why it would lose spark like that? I put a little epoxy around the edges of the magnets so I would be stunned if they came off. If anyone has any ideas or input it would be greatly appreciated. Thank you

 

[The Force power]

Did you check if the Kill-circuit is grounding? (off-switch/Kill-switch/wiring grounding-out)

 

[aMeyers11]

I'm sorry. Stupid question, how do I test that? What wire do I test? I hope the fix is that simple. Thanks for the help.

 

[The Force power]

it may not be that simple, but we'll start with the easy stuff first

where's your on/off switch ?
where's your kill-switch ?

maybe someone can show a schematic for your motor?

 

[aMeyers11]

Well the safety switch is on the controls on the right side of the panel. That is definetly in the on position. I think you put a clip around the switch and when you pull your lanyard away it flips the switch downwards in the off position. I have a wiring diagram but It doesnt seem to help with this issue? The on off switch would just be the ignition switch I guess? I will post the diagram below

 

[The Force power]

yes this is very helpful

If the safety switch & ignition switch in the on position, with a multi-meter check with one lead on a ground and the other lead on the terminal from the Mercury safety switch (with the motor in vertical position)

BLK-YEL wire

if you get a reading...disconnect the safety-switch and check again between a ground & BLK-YEL wire if not the safety-switch is no good
if still a reading check the wire BLK-YEL and ignition-switch (terminal #1) all the way to the switch-block
make sure your ignition-switch is ON (not running)

 

[aMeyers11]

Alright thanks! Just clarifying, when you say check with meter you mean checking voltage? And if the first 2 tests fail then check continuity between the switch lead and switch box?

 

[The Force power]

continuity in all tests, no battery connected OR running engine

 

[aMeyers11]

Alright thank you for the clarification.

 

[The Force power]

Alright thank you for the clarification.

If no reading is showing in previous steps, we move on to checking VOLTAGE at the ignition-coils;
wires GRN-YEL & BLK for ground at Cyl.#1 Coil

set the meter to high AC-volts connect the leads to the terminals of Coil #1 Cylinder or hold them there, start cranking the motor with the starter and measure the AC-voltage

repeat steps with Cylinder #2 Coil with wires GRN-WHT & BLK

the AC-voltage should be 200 volt or more!

report findings

 

[aMeyers11]

I'm sorry for the very delayed response. I hadn't had time to work on the boat for awhile. I took the control box apart to start the testing of the kill switch but my problem is there doesnt seem to be any exposed wire or terminal to touch the test leads to? Any ideas? I will post photos below, thanks!

 

[aMeyers11]

 

[merc850]

The terminals are covered with liquid electrical tape, just poke a test probe into the edge facing out and you should make contact.

 

[aMeyers11]

Alright, sorry for the slow results. Anwyays I tested the kill circuit today and it checks out good. Plan to test the voltage at the coils this weekend. Just havent gotten a chance to work on the boat at all. Thanks for the help!