ignition problems, help!!

[jstaguy24]

OK so I have no spark on all 5 cylinders on a 1991 force 150 with mercury ignition. After some testing I decided to change the switch box. I picked up a switch box on eBay, installed it. Tried to start with no luck, but I did smell smoke, not just raw fuel. I dropped one of the 10/32 nuts so I disconnected the 2 black wires from the converter. Returned with the nut, didn't realize I left the key on. When I touched the black wires to the converter it sparked and sounded like a gunshot. It fired in I don't know which cylinders. After that nothing again. No spark. Is my converter shorted maybe, can't figure why it fired like that.

 

[Jiggz]

Re: ignition problems, help!!

With proper wiring, even leaving the key in the "on" position for a whole day will not result in electrical fire or smoking of electrical component. Because in the "on" position, the only thing you are doing is opening the ckt between the kill switch wire and ground. You need to re-verify our wiring.

 

[pnwboat]

Re: ignition problems, help!!

The 1991 and later 150HP Force motors with the Mercury Thunder Bolt ignition systems are the only Force engines that use the Battery to power the ignition system. This is unlike any of the other Force motors which use a stator to generate the ignition voltage. The stator under the flywheel on a 150HP motor is only used to charge the battery. The battery voltage is stepped up by the Inverter box (sometimes referred to as the Converter box) to 250V, and supplies the voltage to the switch box which fires the coils. Leaving the key in the ON position while connecting the wires on the inverter or switch box could cause a problem.

Here is a link for trouble-shooting the Force 1991-1992 150HP 5 cylinder ignition system. Page 29.

CDI Electronics Practical Outboard Ignition Troubleshooting

NOTE: CDI does sell a stator that has a high voltage ignition winding and a battery charging winding like the older Force ignition systems that eliminates the battery inverter on these motors.

This is the standard CDI replacement OEM stator that only has a battery charging winding. Note it only has two yellow wires that go to the Regulator/Rectifier.

http://www.cdielectronics.com/ProductImages/174-6231K%202.jpg

This is the "Optional" CDI replacement stator that eliminates the inverter box. It has the additional blue wires that go to directly to the switch box.

http://www.cdielectronics.com/ProductImages/176-4796K%201.jpg

If the Inverter box has failed, good luck in finding one. You can look on the auction sites. I recently saw one go for $35. Normal list price is over $400. You can eliminate the need of the Inverter box with the optional CDI stator which is around $225. The switch box is around $280ish.

Good luck. Hope this helps!

 

[jstaguy24]

Re: ignition problems, help!!

It wasnt a problem with electrical smoke, when I touched the ground wire to the converter it sparked the cylinders igniting the fuel that was in there from previous non ignition attempts to start.

With proper wiring, even leaving the key in the "on" position for a whole day will not result in electrical fire or smoking of electrical component. Because in the "on" position, the only thing you are doing is opening the ckt between the kill switch wire and ground. You need to re-verify our wiring.

 

[jstaguy24]

Re: ignition problems, help!!

I have done the testing the best I could, I still dont have a DVA adapter though. I took voltage tests with the meter and got close to the readings listed. But not sure how accurate that is without the DVA adapter. Thats what led me to think the switchbox because I was getting voltage into the switch box. Just nothing to the coils

 

[pnwboat]

Re: ignition problems, help!!

When you connected the two black ground wires with the ignition switch on, it may have caused a voltage spike that may have mimicked a trigger signal which caused the switch box to fire one or more of the coils. Any electronic device does funny things when you mess with the ground connection. I guess the question is did it harm anything?

Without the DVA adapter it's kind of hard to tell, but if the replacement switch box now has the same symptoms as the original switch box, maybe you did damage the replacement switch box, or maybe it was bad from the start. Regardless I would say either the switch box or inverter box or maybe both are bad. My guess is the switch box based on the fact that you seem to have voltage going to it but nothing to the coils......especially if you are seeing 180+ volts on the blue wire when cranking.......but that's pure speculation on my part.

 

[jstaguy24]

Re: ignition problems, help!!

Well this morning I hit the key and it fired right up. So now Im more lost. Guess I'll take it out and try it. Just won't get to far from dock so I can get back with my electric motor

 

[pnwboat]

Re: ignition problems, help!!

Can't argue with that!. Just make sure your Kill Switch and associated wiring is OK and working properly. If the Kill Switch is grounded, it will "kill" the ignition spark to the plugs. Also make sure the battery has a full charge. This particular ignition system depends on the battery to generate a good strong spark.

 

[jstaguy24]

Re: ignition problems, help!!

Well the excitement was short lived, went home put some water to the motor. Started it let it get warm with the cowl on. Shut it off and on. On third try no more spark or ignition. Same as first trip to lake. Ran great for about ten miles. Shut it down to fish. Never started again till last night. Been trying to track it for week's. So I think it would run forever as long as I don't shut it down. Once its running its fine. So I think the switch box is OK. The same probelm has now happened with 2 different boxes.

 

[jstaguy24]

Re: ignition problems, help!!

And the kill wire is pulled at the switch box. I need a puller I guess to look under the flywheel

 

[pnwboat]

Re: ignition problems, help!!

Make sure all of your ground connections for both the switch box and inverter box are making good contact where ever they are attached to the block. I don't think you'll find anything under the flywheel since the stator is only used to charge the battery. Might want to try disconnecting the Regulator/Rectifier to see if that has any affect. If all else fails, the only thing that you haven't tried is the inverter box.

USED MERCURY 332-4796A8 CONVERTER FORCE 150HP 5 CYLINDER | eBay

Without a DVA, it's kind of hard to tell exactly what kind of voltage is coming out of the inverter box. Here's a link that shows you how to put together a DVA using components from Radio Shack. Pretty simple, and it works.

Home Made Peak Voltage Adapter - YouTube

There's also a link noted in the comments below the video that shows the schematic.

 

[jstaguy24]

Re: ignition problems, help!!

Thanks for the info, already had put an offer in that inverter. Hopefully that will be the resolution. And I'll have a spare switch box

 

[Jiggz]

Re: ignition problems, help!!

When there is no spark at all you need to check for voltage output from the trigger ckt. It should be around 0.5V and if there is no voltage from the trigger take a resistance reading and it should be around 48-52 ohms. If there is voltage from the trigger, ensure the blk/yel wire from the switchbox is disconnected (for toubleshooting). Try again and if there's still no spark, check power in and out of the converter box and that is is properly grounded (black wire). Not sure if you have a diagram but here's an isometric diagram. You might have to copy and save it so you can enlarge it.

 

[jstaguy24]

Re: ignition problems, help!!

Its strange, it will fire up in the mornings when its cold. But nothing in the afternoon after the sun is up. And it is warm outside.

 

[pnwboat]

Re: ignition problems, help!!

Sounds like a heat sensitive component. When I used to do electronic repairs, we used to freeze heat sensitive components with a product similar to this.

Techspray Freeze Spray 10 Oz | 1672-10S (167210S) | Techspray

You can also use a can of R134 (environmentally friendly) and attach one of these valves so you can kind of control the spray

Mastercool TAP TOP CAN R134A - Tools - Mechanics & Auto Tools - Automotive Specialty Tools

Maybe try freezing the inverter box or switch box?

 

[Jiggz]

Re: ignition problems, help!!

With reference to freezing as mentioned by PNW, you can also do the other way around by heating the component which in some case is easier to accomplish. You can use either a heat gun or hair dryer to heat up either the CB or SB in the morning when the engine is running. You need to do one unit at a time. I'll start with the CB while the engine is running warm it up. If the engine stops then you know where to look for the source of the problem. The only disadvantage of heating is it's very hard to localized to a specific component unless you use a very narrow nozzle. But for initial troubleshooting to localize the source, heating makes it easy.

 

[jstaguy24]

Re: ignition problems, help!!

Well got the inverter in today. Installed it. Started right up. Warm, cold doesn't matter now. Yeah, time for.a.fishing trip sunday

 

[pnwboat]

Re: ignition problems, help!!

Great! Good to hear that you've got it fixed. Happy fishing!

 

[jstaguy24]

Re: ignition problems, help!!

Thanks everyone for the help