Ignition woes

[BoostedTimmy]

I have a Force 85 which I did a powerhead swap on. During the swap it was found that one of the wires leading to the rectifier was torched. I got a new stator (used part) and it had the different (newer) wire colors. It was pretty easy to to match up the colors, but upon assembly one cylinder didn't have spark. I got a second stator assuming the first part was bad, and behold the same problem. I looked at EVERYTHING electrical on the ignition and am absolutely positive my boxes are fine, the plug wires are fine, the plugs are fine, the coils are fine, and the trigger is fine. I swapped everything and the problem did not follow any of those components. I started tinkering and found I could get spark on all cylinders if I switched the pairs of stator leads that go to the boxes. Sometime during all this I also decided the timing linkage was put back on wrong and flipped it around, but I can't remember exactly when that was.

After getting spark on all 3 cylinders I did get the engine to fire, but as the starter was spinning it would often fire on one cylinder and totally stop the flywheel (bad sound!). Interestingly if I tried enough I could get it to idle smoothly and reliably..however..when I gave the engine some revs on of the stator wires going to the boxes went up in smoke! What was really strange to me is it continued to run fine and spark all 3 cylinders. I could get it started without that wire but it was still very difficult to get it going.

When testing it at the dock it was revving fine but that timing linkage got stuck against the block when I was revving it up. I thought I had it as the manual showed but decided I'd flip it around because there was no other way to get it to work. Since I was taking off the flywheel I decided I'd put the first stator I had got on and see if I could get it working since the previous one had that burnt wire. So I flipped that linkange and swapped the stator. When I went to put the flywheel on I noticed the key was partially cracked I know for a fact it wasn't like that before. Everything back together and the original no spark on one cylinder problem is back, the flywheel stopping when a cylinder fires, and no start.

What could be going on here? It's possible the timing rod wasn't put back 100% as it was and I plan to check that, but that doesn't explain the stator not giving spark. Is the stator with the different colored wires incompatible with my motor? It looks identical except the wire colors. It's firing like I got the plug wires mixed up, except I know I don't! Missing flywheel magnet? What do you guys think?

 

[Tassie 1]

Starter solenoid was the culprit on my '79 Chrysler 70 a few months ago,
smoke, burnt wires etc etc
have a look there as well


a couple of weeks later the ignition module failed while on the water after 30 mins of running,

something else to consider,

 

[Jiggz]

With all the switching of wires done, you need to verify all wires are in accordance with the wiring diagram. What year is this motor? After wiring validation, validate timing starting with zero. Zero the flywheel zero marking with the #1 piston at top dead center. Next, validate timing (static) there is a procedure for this on the top posts on how to do it without running the engine. Set it at 28 degrees BTDC for now.

You repeatedly mentioned not firing on one cylinder, except there are three cylinders so which cylinder is not firing? This is critical especially for the 3 cylinder 85HP motor. If you have the Prestolite ignition system, the top two cylinders are fed from the same CD module while 3rd is fed by its own CD module with a spare circuit.

 

[BoostedTimmy]

I have the prestolite ignition. My motor originally had a stator with 2 blue, 2 yellow, and 2 green and yellow wires if I remember right. When I replaced it, I got the stator that brown/black/yellow, brown/black/blue, brown/blue, brown/yellow, and green/yellow wires. I re-wired according to the attached diagram.

I am now more familiar with the system than I want to be :facepalm: I have checked everything many times and am starting to think I need to find a stator with the matching wires. Here is what's interesting to me - If I wire it as pictured I get no spark on the top cylinder. If I swap the pairs of stator leads the no spark moves to the bottom cylinder! No matter what I else I swap or move, nothing changes, only moving the stator wires makes the problem move.

As for the timing, does anybody have a picture of how that timing rod is oriented? When I have mine as shown in pictures I can find online it hits the block and stops the throttle from opening all the way...

 

[Jiggz]

Year? I understand it is a 85 HP but the year will tell us which wiring diagram to use as a reference.

 

[BoostedTimmy]

It's a 856F7A, so 1987 I believe? This is the diagram I was referring to earlier

 

[Jiggz]

Try this one instead and let us know what happens. For the #3 CDM connect brown/black/yellow and brown/black/blue.
For the #1 and #2 CDM connect brown/blue and brown yellow.

 

[BoostedTimmy]

Like a 4 cylinder? Top 2 fire.

So my current position is no spark on bottom. Coils swapped and problem did not move. Ignition boxes swapped and problem did not move. Trigger leads swapped and problem did not move. Removed white kill wires one at a time no luck.

 

[jerryjerry05]

You do the ohms test on the stators?

1. Resistance readings between the stator wire sets range from 680 - 800 ohms.
2. Disconnect the rectifier. If the engine fires, replace the rectifier.

Test the voltage from the trigger leads?

1. Check the trigger resistance, trigger wire sets read approximately 50 ohms between the wire sets (DVA-5V or more), and open to engine ground.
2. If readings are good, disconnect kill wire from one pack. If the dead cylinder starts firing, the problem is likely the blocking diode in the other pack.

 

[BoostedTimmy]

Some other work has kept me busy, but also made me end up getting a new fluke meter which is giving me much more repeatable results here. I also finally broke down and got a DVA.

Results -
Working leads
765ohms
250v
​​​​​​Dead leads
bad ohm reading (in the mega ohms)
.3v
:lol:

Trigger seems fine. Before I order a fresh stator is there anything else I should check? This is my 2nd used but sold as working stator from eBay that has this problem...

 

[jerryjerry05]

Gotta wonder why it's a "USED STATOR"

If you follow the test procedures from OI.COM or CDI then it could be a bad stator.

Even a stator that tests good can be bad

 

[BoostedTimmy]

Ok new stator and I still got problems. Have WAY more spark now though so I don't feel too bad about the purchase. Ignore everything above, here's what is going on

New Stator
Trigger tests good
All coils good (tested by swapping)
Previously swapped ignition boxes with no change, but am suspect of them now




Top cylinder - Only fires with wire 2 disconnected
Middle cylinder - Fires with all connected, still fires with wire 2 disconnected
Bottom cylinder - No fire. (seen it fire for an instant after swapping wires around but not consistent)

One of my boxes bad? Any other ideas? I'm checking for spark with my timing light if that matters...Both white wires are disconnected for testing. Been swapping these wires a lot so if you see anything weird let me know. I did put the 3 and 1 wires on the same terminal where 1 is but it didn't make a difference and the stator instructions said do it the way I have it pictured...

 

[jerryjerry05]

Your timing light might not be picking up the signal??
Get

this kind of tester.

Try swapping the packs?
You can swap the #3 coil just by moving the wires.

It also sounds like it might be the trigger leads, the black shrink wrap, the skinny wires can break and the shrink can hold it
and seem like it's making contact.

 

[BoostedTimmy]

I decided to just pull the entire "board" off and eliminate those little connectors. I figured best case I fixed a problem worst case I made the wires more reliable and organized. Cut each connector off as close as I could, stripped the wire, then twisted curled and tinned each one. They "hook" around the screws now and are much sturdier. As I was putting it all back on the engine while following the book I realized I had remembered the stator lead order wrong. Got it right and got all 3 sparks. Fires up perfect now. Thanks for all the help everyone!

 

[jerryjerry05]

Yea!!!