Troubleshooting 1993 Force 150

[HotTommy]

Disconnected the tach with no effect. After an hour on the lake it started to run worse. Limping back home it got better, but still not right. .... I'll let the man with far more experience than me see what he can find tomorrow.

 

[HotTommy]

Update:
I just talked with my engine mechanic. He said the stator looked bad. It looked ok until he put it under load when it gave erratic and out of spec readings. Given that the old flywheel had released four of it magnets, it doesn't surprise me to hear the stator may be bad. I plan to have it replaced.

My understanding of the ignition system based on comments from some of you old heads is that the stator's job is merely to recharge the battery. As long as the battery has sufficient charge, the ignition system should work normally. If that is the case, is it likely / possible an erratic stator could create a situation causing the engine to run poorly (what I earlier described as a misfire)? I was working under the assumption that as the battery was new and charged, and the voltmeter showed about 14 volts while the engine was running, my engine had enough juice to fire the ignition system. Was that a bad assumption?

 

[pnwboat]

You are correct in your understanding that the only thing the stator does is charge the battery. 14 volts is the normal reading while the engine is running.

There is one other variable that you need to take into consideration. That is the battery converter box. It takes the battery voltage, steps it up and converts it to AC voltage to supply to the switch box. The converter is no longer made and is only available used or new old stock on the auction sites. It's also about $300 used.

If you plan on replacing the stator, you may want to consider replacing you existing stator with the CDI version that eliminates the battery converter box and supplies the ignition voltage directly to the switch box like in most of the 3 and 4 cylinder Force motors. P/N is 176-4796K1.

 

[HotTommy]

pnwboat,
Question 1: Does that mean the CDI version of the stator supplies both 12v for the battery AND ignition voltage to the switch box?
Questioin 2: If the old converter box were producing low voltage (i.e., less than 260 volts) might that account for my engine misfire problems?

 

[HotTommy]

Duplicate post.

 

[Frank Acampora]

In reading back over past replies, it appears that your 150 has Prestolite ignition, not Mercury since Mercury ignition uses only one box for all cylinders. Prestolite ignition (at least mine) has two separate charging windings for three CD boxes AND a battery charging winding. Thus, the Prestolite ignition is independent of the battery and failure of the battery charging portion of the stator will not affect running. HOWEVER intermittent problems with any of the ignition winding will affect running.

 

[pnwboat]

[QUOTEpnwboat,
Question 1: Does that mean the CDI version of the stator supplies both 12v for the battery AND ignition voltage to the switch box?
Questioin 2: If the old converter box were producing low voltage (i.e., less than 260 volts) might that account for my engine misfire problems? ][/QUOTE]

1. Yes it does. The CDI version stator P/N176-4796K1 has two windings. One to supply voltage to the Switch Box, and one to supply voltage to the Rect./Reg. It has four wires, two Yellows (Rect./Reg.) a Black (ground) and a Blue (Switch Box). Your original stator only has one winding to charge the battery. It should only have two yellow leads. Here is some installation instructions from the CDI WEB site. You basically remove the old converter box, tape up or remove the wires that went to it and hook up the new Blue stator wire to the Switch Box.
http://www.cdielectronics.com/wp-content/uploads/2013/09/IS-176-4796K-1.pdf

2. If the converter box does not supply adequate voltage to the Switch Box, it will affect ignition system performance. Just keep in mind that the Switch Box itself could cause an issue too. You mentioned that the previous owner had replaced the CDI which is kind of vague, but I would bet that it was actually the Switch Box. The converter boxes are pretty hard to find, but it's anyone's guess as to what the previous owner actually replaced.

 

[HotTommy]

Finished at last! My "mechanic" took three weeks to do little more than check out the stator with a multimeter. At my age, my time is more valuable than my money, so I ordered up a new stator with built in converter output, and a new switch box. I took the boat back from the "mechanic" and installed both today. It runs fine now. I don't know which of the three was most responsible for the misfire, but my money is on the switch box. When i took the old one off, the back side showed signs of swelling. ... Thanks to all for your help. That's it for now.

 

[pnwboat]

Well at least it's working now and you've eliminated the converter box. Hope the rest of the summer is "uneventful" if you know what I mean! LOL!

 

[HotTommy]

One of the reasons I take on projects like this motor is because I enjoy solving challenging problems. But THIS one just didn't want to end. The satisfaction to frustration ratio on this project was very low. ... I too hope for the rest of the summer to be no more challenging than the occasional thunderstorm.

 

[Jiggz]

Congrats and enjoy!