No spark 90 hp 1999 Force after switchbox replacement

[jcaceem]

Hi,
Went to the launch and my boat wouldn't start after a previous day of fishing. No spark.
Ordered a new switchbox, trigger and stator not knowing which would be the culprit. Once the switchbox was replaced the engine fired right up so returned the trigger and stator.
Next trip the engine wouldn't start at the end of the day--got towed in. Again, no spark. Ordered another switchbox and installed and still no spark.

The first replacement had two red wires where my original had only one. The first replacement came with a splice for both of the red wires to be connected to my one red wire on the engine. On inspection you could tell the red wire splice overheated and so did one of yellow wires. I was sure that the first replacement switchbox burned up and the 2nd replacement would work. It does not. I did not hook up the extra red wire.

Could there be something else? I find it odd that replacing the switchbox worked the first time--again, it immediately fired up and ran for a day--and now it doesn't. Could something else have failed due to the two red wires being connected instead of just one?

There is power to the switchbox.

 

[pnwboat]

Disconnect the Black/Yellow wire on the Switch Box. This is the ignition "Kill" circuit. If you get spark with the Black/Yellow wire disconnected, then you have either a bad Kill switch or a short to ground on the Black/Yellow wire.

NOTE: If the engine starts with the Black/Yellow wire disconnected, the ignition switch will not shut the motor off. You have to either choke the motor, or take your hand and cover the carb(s) to stop the motor.

 

[jcaceem]

Disconnect the Black/Yellow wire on the Switch Box. This is the ignition "Kill" circuit. If you get spark with the Black/Yellow wire disconnected, then you have either a bad Kill switch or a short to ground on the Black/Yellow wire.

NOTE: If the engine starts with the Black/Yellow wire disconnected, the ignition switch will not shut the motor off. You have to either choke the motor, or take your hand and cover the carb(s) to stop the motor.

Thank you for responding. Both my engine and switchbox have two yellow wires. No wire that is black and yellow. Is one of the yellow wires for the kill circuit?

 

[pnwboat]

Usually the yellow wires are that come from the stator are the battery charging circuit. Hmmm, I'll look a t a wiring schematic. Are you positive that it's a 1999 with a Switch Box? I believe that they stopped using the Switch Box ignition system around 1995.

From what I can see in the schematic, it looks like the B/ack/Yellow wire in the wiring harness gets changed to a Black wire at a connector, then goes to the Switch Box.

 

[jcaceem]

Usually the yellow wires are that come from the stator are the battery charging circuit. Hmmm, I'll look a t a wiring schematic. Are you positive that it's a 1999 with a Switch Box? I believe that they stopped using the Switch Box ignition system around 1995.

From what I can see in the schematic, it looks like the B/ack/Yellow wire in the wiring harness gets changed to a Black wire at a connector, then goes to the Switch Box.

I may be using the wrong terminology. It is the voltage regulator on the side of the engine. This is the original part.

 

[pnwboat]

OK now that makes more sense. You are correct, that is the Voltage regulator. That typically is not involved in the ignition system, however, it can affect it, since the charging voltage is generated by some seperate coils on the ignition stator. The ignition stator has another set of windings that generate the voltage for the ignition system.

I suspect that it was simply coincidental that when you changed the voltage regulator, your spark returned. First I would check your "Kill Switch". Typically it's mounted on the dash or on your throttle control. If it's on your dash, you might have a lanyard that has a plastic piece that slips under the Kill Swtich. If it's on your throttle, you might have a switch that has two positions. Run and Stop or a switch with a lanyard.

If that checks out OK, then look at your CDMs (Capacitive Discharge Module). There is one for each spark plug. They look like ignition coils, because the spark plug wire goes from the top of them to the plugs. Each of them has a 4 pin modular connector.

Unplug the 4 pin modular connector for the top plug. Crank the motor and see if spark returns, or the motor tries to start. If no change, Plug it back in and do the same with the next CDM. If the spark returns after unplugging the second CDM, then the second CDM is bad and is preventing any of the CDM's from firing. Do that for all 3 CDM's.

 

[jcaceem]

OK now that makes more sense. You are correct, that is the Voltage regulator. That typically is not involved in the ignition system, however, it can affect it, since the charging voltage is generated by some seperate coils on the ignition stator. The ignition stator has another set of windings that generate the voltage for the ignition system.

I suspect that it was simply coincidental that when you changed the voltage regulator, your spark returned. First I would check your "Kill Switch". Typically it's mounted on the dash or on your throttle control. If it's on your dash, you might have a lanyard that has a plastic piece that slips under the Kill Swtich. If it's on your throttle, you might have a switch that has two positions. Run and Stop or a switch with a lanyard.

If that checks out OK, then look at your CDMs (Capacitive Discharge Module). There is one for each spark plug. They look like ignition coils, because the spark plug wire goes from the top of them to the plugs. Each of them has a 4 pin modular connector.

Unplug the 4 pin modular connector for the top plug. Crank the motor and see if spark returns, or the motor tries to start. If no change, Plug it back in and do the same with the next CDM. If the spark returns after unplugging the second CDM, then the second CDM is bad and is preventing any of the CDM's from firing. Do that for all 3 CDM's.

Thank you so much, I will check this tomorrow!!!

 

[jerryjerry05]

outboardignitiondotcom has test procedures for
your motor, you can do the basic tests with a regular
analog meter but the more technical you'll need a
peak reading/DVA volt meter.
pnwboat said the reg wouldn't stop the spark. But
it can." from O.I.

1. Disconnect the yellow wires from the stator to the rectifier and retest. If the engine fires, replace the rectifier.

This sounds more like a stator problem.

No Fire At All: Disconnect the black/yellow kill wires from the harness and RPM Limiter. Retest. If the engine’s ignition fires now, the kill circuit has a fault-possibly the keyswitch, harness or shift switch. Disconnect the yellow wires from the stator to the rectifier and retest. If the engine fires, replace the rectifier. Check the cranking RPM. A cranking speed less than 250-RPM will not allow the system to fire properly. Check the stator resistance and DVA output as given below:
	Wire​	Read To​	Resistance​	DVA​
	White/Green​	Green/White​	500-700​	180V or more​

 

[jcaceem]

outboardignitiondotcom has test procedures for
your motor, you can do the basic tests with a regular
analog meter but the more technical you'll need a
peak reading/DVA volt meter.
pnwboat said the reg wouldn't stop the spark. But
it can." from O.I.

1. Disconnect the yellow wires from the stator to the rectifier and retest. If the engine fires, replace the rectifier.

This sounds more like a stator problem.

​

No Fire At All: Disconnect the black/yellow kill wires from the harness and RPM Limiter. Retest. If the engine’s ignition fires now, the kill circuit has a fault-possibly the keyswitch, harness or shift switch. Disconnect the yellow wires from the stator to the rectifier and retest. If the engine fires, replace the rectifier. Check the cranking RPM. A cranking speed less than 250-RPM will not allow the system to fire properly. Check the stator resistance and DVA output as given below:
	Wire​	Read To​	Resistance​	DVA​
	White/Green​	Green/White​	500-700​	180V or more​

Thank you for mentioning this website! Lots of great information and parts. I thought stator as well but the battery doesn't drain when in use so I was thinking maybe something else. The guy I had look at my engine said the stator looked brand new so he didn't replace it--of course he could have been wrong. This was after it started when the first voltage regulator was put on. No one in my area works on a motor that is over 10 years old so troubleshooting has come down to me and this guy that has worked on outboards before. He does good work but electrical isn't his expertise.

 

[Redbarron%%]

Will it run now with the regulator disconnected?
Check for spark as there might be another problem.
Also sometimes one or more magnets come loose and would give a scraping sound as the motor is turned (plugs out by hand).
Also check for spark whole the plugs are out as the engine will turn faster.
If turning lower than the coming in speed of the magneto you will get no spark.

 

[jcaceem]

Thank you all so much for the help. I have a feeling it is the stator but I am going to order coils and trigger just in case. Worst case I have extra parts I need if the original fail during a fishing trip to the coast.

 

[jerryjerry05]

The trigger and coils rarely go bad on these motors.
The Amphenol connectors do go bad.
They get hot and loose contact.
The coil in some cases can go bad but not all 4 at once.
I've not seen a trigger go bad for a LONG time.
In 95 they went from Force/Prestolite to Mercury ignition.
In some cases they started using Mercury as early as 91/92.

 

[jcaceem]

The trigger and coils rarely go bad on these motors.
The Amphenol connectors do go bad.
They get hot and loose contact.
The coil in some cases can go bad but not all 4 at once.
I've not seen a trigger go bad for a LONG time.
In 95 they went from Force/Prestolite to Mercury ignition.
In some cases they started using Mercury as early as 91/92.

Sorry for my ignorance but what is an amphenol connector?

 

[jerryjerry05]

It's the connector on the end of the wire on just about every Mercury
electrical part sold.
The plug in, male/female connector.
Usually turning black from overheating.

 

[Redbarron%%]

AKA Bullet connector. They (loosely) connect electrical wires.
They get dirty, have bad connection, get hot and lose their connection tension.
The heat turns the vinyl protective cover black.
Cleaning them and slightly squeezing the female side can sometimes help make a good connection.
The high current connections to the rectifier/regulator often degrades these connectors.
Here is a picture of some with heat shrink wire insulation for marine use to try to control corrosion of the wire.