1990 Force 120, no spark (after just having been running)

[khnitz]

I had started this discussion in another no-spark thread, but am moving it here as suggested by jerryjerry05.

The engine turns over but doesn't fire. I was running/idling the motor for about 20minutes on a Saturday a couple of weeks while I was removing the cover from our lift in preparation for taking the boat out of he water for the season. I shut the motor down, then went to re=start it just o be sure that it would fire up once I was ready to move it when my helper was in place with the trailer at the boat ramp. When I went to re-start it (we're talking ~1minute since I had turned if off), it wouldn't even turn over. Nothing. Not a blip from the choke or the starter solenoid...nothing.

I came to find that the B (12V from the battery) contact on the ignition switch had cracked off. I replaced the ignition switch, but still struggled all day last Sunday with the engine not turning over. Once I verified all the wiring between the ignition and kill/safety switch to the motor, and installed a fully charged battery, then I could get the motor to turn over, but had poor/low spark readings (I was using a Check Spark on the plug wires for the readings).

Old news (from previous thread): After reviewing the forums here and the troubleshooting guide at outboardignition.com, I'm thinking that my rectifier is fried. I'll try disconnecting that and see if the engine will start (and if it does, then I'll be replacing the rectifier). The stator and trigger contacts Ohm'd out correctly, btw. There's a slight sign of overheat/melt on the rectifier body near one of the mounting screws for the rectifier, which also makes me think something is up with it.

Old update (from previous thread): I disconnected the rectifier and tried to start the boat, but it still didn't start. Although this time around the Check Spark showed low spark on Cyl's 1-3, and no spark on Cyl 4 (where before disconnecting the rectifier it showed low spark on all 4).
And, so much for measuring the rectifier or otherwise testing it...as I was removing it from the powerhead it slipped away and into the river. Son of a !@#@#%@#$. Looks like I'll be getting a new rectifier, at least. Update - the new rectifier was ordered and has arrived. I haven't had a chance to install it, yet.

Suggestions from previous thread by submariner1980: Don't worry about trash rectifier. Good replacement is: SPI Universal Voltage Regulator / Rectifier at Rogue Motorsportz. And it will protect battery from overcharging. Check grounding wires from both CDI modules to powerhead and grounding wires from coils to powerhead.

Suggestions from previous thread by jerryjerry05 <with my comments>:
You should start your own thread. <done >
First do a compression test. <will do. motor has about 50 hours on it since a rebuild in 2007. I did the rebuild, just haven't had much time to use the boat>
Then replace all the wire ends,the connection under the shrinkwrap can be bad. <I'll check them>
The having spark and then no spark could be the connectors.
How are you testing the spark? <using a Check Spark - it's my friend's invention - Welcome to CheckSpark Engine Ignition Analyzer >
You need a spark tester or sparkies.
Holding it against the block isin't the way to do it.
Usually "weak" spark is the stator.
They used 2 types of ignition systems on the 1990/120
What do you have? Pics? <I'll post more pics, but it has the Blue CDI modules and the 4 Blue Coil packs...those are all original>

Of course, it's getting colder here (far NW suburbs of Chicago), and we're supposed to have snow tomorrow. It may wind up sitting on the lift over the Winter

 

[submariner1980]

Re: 1990 Force 120, no spark (after just having been running)

Good picture khnitz!!!
What I can see it is a some electrical corrosion around negative grounding terminal of rectifier. Is this jumper-fuse is not fried? The cause of corrosion could be
1. Bad loosen dirty connection.
2. Current exceeds normal due to a) faulty battery, b) shorts in wires, control box, gauges wiring.
Try to disconnect two yellow wires from rectifier, check ohms. If it is out of spec probably there is some shorts in alternator stator windings after high current.
It will affect charging coils voltage and spark will be weak

 

[submariner1980]

Re: 1990 Force 120, no spark (after just having been running)

Try to crank motor with disconnected yellow wires, check kill wire terminal(should be no ground) or disconnect wire from control box to kill wires terminal.
Don't hurry to buy new stator, alternator can be re winded in the electric motors shop for almost nothing.
BTW.
Test spark analyzer is funny toy not a tool.

 

[jerryjerry05]

Re: 1990 Force 120, no spark (after just having been running)

The ignition is the older Prestolite system.
The regulator is from the newer system/style.
The pic shows it's wired wrong.
It has 4 lugs and only 3 are used????
Submariner:can you post a link to the shop that will re-do the stators?
A while back someone posted a link to a place that had stators and packs cheap.
I'm thinking: Chicago magneto, maybe standard magneto?? Something like that.
I had it bookmarked for reference but my bookmarks disapeared??

 

[submariner1980]

Re: 1990 Force 120, no spark (after just having been running)

To Jery
I 'll try to find and post here. just few days ago I have read this article with pictures

 

[submariner1980]

Re: 1990 Force 120, no spark (after just having been running)

To Jery
Rebuild your bike's expensive stator Here is link, sorry it's not exactly for outboards but idea will work.

 

[submariner1980]

Re: 1990 Force 120, no spark (after just having been running)

http://i44.tinypic.com/52wew.jpg
It has 4 lugs and only 3 are used????
Negative post of rectifier connected by jumper fuse to the mounting screw and motor
Yes, the cheap parts for FORCE here force parts

 

[Jiggz]

Re: 1990 Force 120, no spark (after just having been running)

As Jerry mentioned, there seems to be a missing wire but looking further it seems the negative output terminal of the rectifier is hard wired with one of the mounting bolts which is also acceptable as long as it is properly grounded. If not, connect a ground wire to the negative terminal. I've attached a wiring diagram.

Note the blk/yel wire from both modules, disconnect this from the engine compartment terminal board and make sure it does not touch ground. Better yet tape with electrical tape temporarily. Keep both stator yellow charging wires disconnected for now, tape ends if you must but make sure they do not touch each other or to ground.

Check both 2 sets of stator power wires, make sure they are connected and matched properly (do continuity or resistance check, each pair of wire should read 680~800 ohms. Try again and if problem persists, check for stator cranking voltage output, this is better done with a DVA adapter and the output should be at a minimum of 180+ peak.

If you do not have a DVA you can still try using a digital voltmeter and read the RMS equivalent which is around 127~128VAC rms. Just make sure you are reading on proper pair of wires. Re-post your diagnosis. You might have to save, enlarge and print the diagram to better see it.

I almost forgot, if after disconnecting the blk/yel wire and the engine started, you cannot turn it off with the ignition switch, instead you need to ground the wire to kill the engine. Not even the kill switch will work while the wire is disconnected at the engine terminal board. Careful, this is an energized wire (when engine is running) so make sure you avoid touching the bare wire or terminal.

 

[khnitz]

Re: 1990 Force 120, no spark (after just having been running)

Here is a picture of an outboard like mine, showing the coil packs:

I have disconnected the rectifier, taped up the connections and cranked...the motor did not start.

I know the inventor of the Check Spark, it is not a toy. There are certainly the other established alternatives, and I will check with those, too. That same inventor created this and has done quite nicely from it, too, over the years.
Sperry Instruments

The rectifier was grounded through the mounting screws, which were fastened securely. Still, the signs of overheating are there, which makes me think the connection was less than stellar.

When I measured across the stator windings, I did get a reading within the specified range. Also, I measure across the trigger wire pairs, too, and got resistance readings within spec. I have not had a chance yet to measure the output voltage on the stator while cranking. It is getting pretty cold, here ;-)

 

[submariner1980]

Re: 1990 Force 120, no spark (after just having been running)

Hmm? It is really weird two power packs are down simultaneously.
Or two charging coils? Or four spark coils? Something is going wrong in circuit connected to both power packs. Did you check a kill wires with ohmmeter, is it infinity between wires and ground(motor block)?

 

[jerryjerry05]

Re: 1990 Force 120, no spark (after just having been running)

Try changing all the wire connectors.
Sometimes under the shrinkwrap the connections break and the problems start.
My 85 was missing,no spark then spark.
So I was checking and the test said the stator was toast.
So I changed the stator to a know good one(tested good on the bench).
Then the same problems??
So started wigglin the wires and 1 came apart in my fingers.
I replaced ALL the wire connectors,stator and trigger and both packs.
That solved my problem.The original stator had bad connections too.
The stator from a 85 will work if the years are close.

 

[Jiggz]

Re: 1990 Force 120, no spark (after just having been running)

So far you have tried disconnecting the rectifier but have yet to hear if you did the kill wire (blk/yel). This has to be disconnected from the engine terminal board to ensure it is totally isolated. Please let us know as soon as you have this done.

 

[jerryjerry05]

Re: 1990 Force 120, no spark (after just having been running)

The pic doesn't show the 4th wire grounded anywhere I can see.
This regulator has 2 mounting posts.
Neither is used.
The 4 lugs are part of the circutry.all need a wire.
The negative terminial isin't connected to anything.
There is a bit of paint gone between the mounting screw and the terminal.
I don't know how the inside of the regulator is wired?? Anyone have a diagram?
I've got a way to test the reg. Just can't scan it.
The whole book won't go through the scanner I have

 

[Jiggz]

Re: 1990 Force 120, no spark (after just having been running)

In the pics with the red arrow I assume is a metal conductor connecting the negative terminal to ground. Of course, there is only one way to find out by conducting a continuity test.

 

[submariner1980]

Re: 1990 Force 120, no spark (after just having been running)

Few words add to Jiggs comment, This metal conductor is calibrated to burn out if current exceed normal. I guess 10 amps
Inside this rectifier is simple diode bridge, no voltage regulation.

 

[jerryjerry05]

Re: 1990 Force 120, no spark (after just having been running)

Your missing the point.
IF there is a "bridge"there??
It still should have a wire connected to it.
Otherwise it wouldn't be there????
It really doesn't matter, he's dropped it overboard anyway

 

[submariner1980]

Re: 1990 Force 120, no spark (after just having been running)

Gotcha!
I'm talking about pic and you about motor eace:

 

[jerryjerry05]

Re: 1990 Force 120, no spark (after just having been running)

????

 

[khnitz]

Re: 1990 Force 120, no spark (after just having been running)

Sorry, it's been cold here and I haven't been able to get more troubleshooting done.

Yes, the original rectifier is practicing for the Olympic Swim Team tryouts, so further measurements on that one are not possible ;-)

In my course of trouble shooting so far, I completely disconnected the kill-circuit at the engine. I then checked each line (for the starting solenoid, and for the magento kill circuit (BLK/YEL) back to the Ignition switch and kill switch. They both measured out OK, with no short in their paths. I also removed the pins from the connectors under the dash and verified that there was a good connection through the pins, too (in case of corrosion, etc).

The weather is supposed to be a little warmer this weekend, so I may get some time to investigate further. My measurements of the stator windings and trigger windings during troubleshooting were within spec.

The darn thing was running not 60 seconds prior to it not running. Ugh.

I do appreciate your help! And just so you understand a bit of my background, I am a degreed EE with practical experience repairing electronics and vehicles, as well. I have an Oscilloscope, which would be perfect for viewing the signal off of the stator and trigger circuits, but it's not exactly portable

Happy Thanksgiving!

 

[Jiggz]

Re: 1990 Force 120, no spark (after just having been running)

With your background the spark problem should be pretty easy to troubleshoot. However, do you know for sure there is no fuel related problem why the engine will not start?