1991 90hp Force Outboard ignition problem

[Josh58]

Hi, I"m working on my father in law's 90hp force outboard motor. We first were checking out the charging system. The motor ran and after working with the charging system, there is no spark.

The background:
The thing wouldn't charge, I read the clymer book and troubleshot the rectifier. I'm pretty sure that it is bad. If you check from the AC terminal to the rectifier positive you get 100 k ohms, reversed the leads and it's 170k ohms. When you check it to the other AC terminal you get 1 ohm, reverse the leads and then you get 1 ohm. Anyways I marked the wires as they came off. I hooked them back up and noticed that the circuit breaker was tripped. I reset the circuit breaker and noticed that someone had taken the rectifier positive and hooked it to the starter side of the starting coil. I said that wouldn't work and I changed it to the battery side of the coil. I then hooked up the rectifier negative to one of the starter bolts. When we went to hookp up the positive cable on the battery, it acted like something was pullying juice because it was sparking. We unhooked it and looked around. Now someone has messed with this before because the wiring has been changed around. After looking at it, I found that the rectifier positive was hooked up to the wrong side of the circuit breaker, so there was no protecting according to the wiring diagram.

Bigger problem:

Now I have no spark at the spark plugs. I unhooked the two black wires that come off the cd modules that go to the kill switch in the boat. No spark. Hooked those back up. I put all the wires back like they were before I started with the rectifier. It almost sounds like something is sparking around the stator area. whoever had this boat before had a problem and didn't finish. I"m thinking that the rectifier diodes are shorted through one side of the rectifier. But now that I don't have a spark. I'm afraid that maybe the stator is screwed up or the cd modules. I checked the voltage output of the stator to the 2 cd modules and I had around 168 volts. I have a true rms VOM meter. I don't have the peak voltage one they talk about in the manual. They say in the manual that you need 220 volts to the cd modules. It's rather frustrating since I was just checking the charging circuit. I"m wondering if the stator is a bunch of different windings insulated from each other, or if it is all one set of wires and that if the rectifier shorted, that it could mess with the ignition system. I won't be able to check this until tommorow night. Any help would be great.

Thanks,

Josh

 

[Frank Acampora]

Re: 1991 90hp Force Outboard ignition problem

If this is NOT a mMercury ignition, there are three discrete windings on the stator. One set of heavy coils covers 10 poles. This is the 12 volt A/C/charging coil. Then, there are two separate fine windings covering 5 poles each. These are the two 200 volt CD box charging circuits. Add up the poles and you see why it is called a 20 pole stator. Force ignitions will have a small black rectifier and mercury will have an aluminum box "potted" with clear epoxy. You can see the circuit board.

You did connect the rectifier terminals correctly and yes, most likely there was an internal short. However USUALLY the 12 volt charging system is separate from ignition and will not affect it. However, in your case the P.O. has messed with the wires and you really need to check every connection and wire. One thing you defintely need to do is check the ground from the CD mounting plate to the block.

Since the engine did run, you need to check all ignition components and wiring. Usually, because they are on separate poles overheating one set of coils will not affect the others but -- there is always the possibility that the 12 volt system has affected the ignition, so pull the flywheel and check the stator. Look closely at the junction where the two different windings are close to each other.

 

[ben jones]

Re: 1991 90hp Force Outboard ignition problem

I just had a similiar problem, I could not pin point what was wrong I thought it was the pre amp in my distributor. If you hook everything up, set the timing at tdc then disconnect the black and white terminal from the distributor and ground it on the motor block, do this while you have the top piston spoark plug out and have the threads grounded on the hole. If it sparks then everything is good, your problem is probably the pre amp. Do me a favor just for fun see what happens when you switch the black and white and ythe blue wires on the distributor. if the pre amp is bad it wont hurt anything. you can also check the pre amp by taking it out and hooking it up to check it by putoing a screw driver in fromt of the led sensor. i read there is no way to check it but i made it work outside the distributor.
to check the stator see if there is continuity from lead to lead that should tell you. Try the switching wires thing you might be suprised

 

[Josh58]

Re: 1991 90hp Force Outboard ignition problem

Thanks for your input. Hopefully this weekend, I can take the flywheel off and check the stator. I also need to check the other wires. Hopefully it is just something simple.

Thanks

 

[Josh58]

Re: 1991 90hp Force Outboard ignition problem

It's been awhile but we finally got the boat running. The stator does have 2 distinct windings. If you get a replacement from cdi it will all be one winding. The trigger assembly was checked and it was hard to tell if it was bad with the PVA adapter. We got a trigger from cdi but it didn't fit right and it was reading .6 volts for 1, .4 for number 2 and .2 on number 3 cylinder. It appeared to not work right. They warrantied the trigger because of the warpage. We recieved the new trigger and it is doing the same thing. There was still no spark so the next thing was the ingition modules because they were not sending out any volts to the coil packs. The one module had an extra lead that wasn't being used since it was just being used on one cylinder. I tried hooking that lead up and there was still not spark. After replacing them the boat started right up. We have to remove the flywheel again and do some sanding on the trigger assembly so it will move with the throttle linkage. This is a minor problem. If I have to troubleshoot a trigger again, I think I will try cdi's trigger test kit to avoid weird readings. It wasn't my meter because it is a 400 fluke 87 meter. But the readings coming from the trigger assembly was not consistent. The spark plugs were removed so it would turn over easier for the check. Oh the starter was having problems before all of this and it went bad during all of this. All of it came down to the rectifier being bad and wired wrong. When I went to test it, it must have sent a shock to the ingition modules through the ground and burnt them up. This was probably one of the harder issues that I have had to troubleshoot. So after we replace the water pump and check the timing this boat will be ready for the water again........... Hopefully this helps someone else.

 

[roscoe]

Re: 1991 90hp Force Outboard ignition problem

Good job, happy boating.