force 150 no spark

[Gerard1970]

So, 2 weeks ago I started it up and it ran great. I replaced the impeller a week ago, go to start it and it turns over, but no spark. I tested for spark the old fashioned way by pulling plug and grounding it while turning the key....no spark. What is going on?!. Checked the neutral switch, kill switch on the dash, wire connections on motor. Wondering if I cut a wire somewhere and is it possible to remove all leads going in to motor to test? I am at a loss. Thanks in advance.

 

[Jiggz]

Re: force 150 no spark

What year is this motor? Anyways, try locating the kill wire from the terminal board in the cowling and disconnect it and then temporarily tape it (make sure it does not touch ground). Try again.

 

[Gerard1970]

Re: force 150 no spark

I disconnected the kill wire on the motor, checked for open circuit on the kill switch on the dash and still no go. Checked the fuse on the motor also and nothing. . Grrrrr..I will keep looking and thanks for the reply.I believe the motor is a 1992.

 

[pnwboat]

Re: force 150 no spark

There were two ignition systems used on the 1992 150HP motor. The Prestolite system that has 3 light blue CD Modules and 5 light blue coils. The Mercury ThunderBolt system has a battery converter box, a Switch Box and 5 dark blue coils. From the symptoms you describe, no spark on any coil, I would suspect that you have the Mercury system. Can you confirm?

 

[Jiggz]

Re: force 150 no spark

I am assuming you are referring to the blk/yel wire at the switch box that you disconnected already. Make sure with the ignition in on position, there is power going to the purple wire in the converter box and the black wire is properly grounded. Do you have a wiring diagram?

Also, when you mentioned, "checked for open circuit on the kill switch" technically, the kill switch is normally open when it is closed it kills all sparks thus the motor. Just want to clarify.

 

[Gerard1970]

Re: force 150 no spark

I just picked up a manual, so I will get back to you in a bit on the ignition system. I will have to check for power to those wires tomorrow.... off to work. The motor turns over no problem, but can a faulty key switch cut off my spark, but still turn it over? Thanks for the patience and help guys.. boat was supposed to go in the water Sunday. Good thing I checked!

 

[Gerard1970]

Re: force 150 no spark

It sounds like I have the Mercury system..

 

[pnwboat]

Re: force 150 no spark

The ignition system on this motor uses the battery to supply voltage to run the ignition system. It uses a battery converter (see pic. below) to take the 12 volts DC from the battery, steps it up converts it to AC voltage which is then supplied to the Switch Box. The Switch Box takes the AC voltage and converts it to DC to be stored in a capacitor which is then triggered by the trigger signal and discharged into the appropriate ignition coil.



Make sure you have 12 volts DC on the red wire on the converter box. When you crank the motor, you should see some AC voltage on the purple or blue wire going to the Switch Box. Can't remember which off the top of my head. Jiggz already mentioned check the ground connections.

 

[Gerard1970]

Re: force 150 no spark

The ignition system on this motor uses the battery to supply voltage to run the ignition system. It uses a battery converter (see pic. below) to take the 12 volts DC from the battery, steps it up converts it to AC voltage which is then supplied to the Switch Box. The Switch Box takes the AC voltage and converts it to DC to be stored in a capacitor which is then triggered by the trigger signal and discharged into the appropriate ignition coil.

View attachment 230509

Make sure you have 12 volts DC on the red wire on the converter box. When you crank the motor, you should see some AC voltage on the purple or blue wire going to the Switch Box. Can't remember which off the top of my head. Jiggz already mentioned check the ground connections.

Great info! Now I have an idea what they all do. Thanks so much...

 

[Gerard1970]

Re: force 150 no spark

Ok...have voltage going to the converter box, checked the purple wire going to switch box and getting 00.5 volts..any ideas? It is showing 27.1 volts on the red.

 

[Gerard1970]

Re: force 150 no spark

I am at a loss

 

[pnwboat]

Re: force 150 no spark

Are you sure you're getting 27.1 volts on the red wire on the converter box? It should be 12 volts DC from the battery.

 

[Gerard1970]

Re: force 150 no spark

Sorry...yes 12 volt..and 0.36 volt from the purple.

 

[pnwboat]

Re: force 150 no spark

Check the purple and blue wires on AC volts while the motor is cranking. I believe you should see over 100 volts AC on the blue wire, not sure about the purple one.

 

[Gerard1970]

Re: force 150 no spark

Just checked again. Set the meter to 200 volts ac and on the blue was nothing and on the purple was 00.5. Any ideas?

 

[pnwboat]

Re: force 150 no spark

Make sure the ground wire on the converter box is making good contact with the block. Disconnect the blue wire from the converter box and check the terminal on the converter box that the blue wire was attached to while cranking the motor. Then reconnect the blue wire and disconnect the purple wire and see what you see on the terminal on the converter box.

 

[Gerard1970]

Re: force 150 no spark

Ok....did as you asked. The blue wire disconnected, while cranking was between 16-17.2 volts ac. The purple wire was all over the place, but did catch 135, 165, etc. It was all over the place. Hope this helps.

 

[pnwboat]

Re: force 150 no spark

Ok, did you disconnect the Black/Yellow wire on the Switch Box earlier?

 

[Gerard1970]

Re: force 150 no spark

Yes I did, but put it back after the last test....was I supposed to keep it off?

 

[pnwboat]

Re: force 150 no spark

No, but try disconnecting the Black/Yellow wire on the switch box now, with the purple and blue wires connected and see what you read on the the purple and blue wires while cranking the motor.