1988 85 hp. Odd situation, what did I fry?

[UncleBuck81]

I rarely get stumped this bad, and I am, need the pros help.

To sum up, motor won't fire. She turns over fine and has fuel delivery (rebuilt carbs and fuel pump 2 months ago and boat has been used twice a week). She has spark on 3 and weak spark on 2, no spark on 1.

Last trip out hit some large waves. I didn't know it at the time but it broke one of the rubber shock mounts that hold the ign components. It put strain on some wires and burnt them a little. All wires have been replaced that were damaged, and all others read out 0 resistance. I have swapped coils, problem stays at 1 and 2 cyl. Also have a donor motor, tried swapping power packs, same result.

I have also tried disconnecting rectifier, no difference, even replaced it. Also tried disconnecting white kill wire at each power pack.

I am stumped. Any help or ideas would be much appreciated.

 

[pnwboat]

Re: 1988 85 hp. Odd situation, what did I fry?

Have you checked the stator? Check the resistance between the two sets of Blue and Yellow wires from the stator. Resistance between each pair of Blue and Yellow wires should be 680 - 850 OHMs.

 

[UncleBuck81]

Re: 1988 85 hp. Odd situation, what did I fry?

Hey pnw, sorry forgot to put that in there. Yes blue/yellow read out fine. They were about 740 each, I don't have a dva though.

 

[pnwboat]

Re: 1988 85 hp. Odd situation, what did I fry?

Check the spade lug connectors on the ends of the CD modules and trigger wires. Some of them have a small piece of black heat shrink tubing that covers the solder/crimped wire connection. Sometimes the wire breaks off inside the black heat shrink tubing and you can't see that it's broken. I've also seen where 1 single strand of wire is the only thing making contact. It OHMs out OK, but it's not enough to pass a low voltage trigger signal or CD Module voltage.

Also keep in mind that a bad CD module may produce good spark, but prevent the other good module from firing at all.

Make sure that the ground wire from the coil mounting plate to the engine block is making good connection. This is the ground reference for the CD Modules and coils.

 

[UncleBuck81]

Re: 1988 85 hp. Odd situation, what did I fry?

Thanks, I will try replacing all those spade connectors. Hopefully that's it, if not I will go crazy!! Hahah thanks for the idea

 

[UncleBuck81]

Re: 1988 85 hp. Odd situation, what did I fry?

Well PNW you were right!!! Based off your suggestion I re-read out all the wires after removing the black shrink wrap. Sure enough, the #1 orange wire from the trigger had like 3 strands to the spade connector. It read out at 53 too just like it was supposed to and still proved to be bad. Now she fires up again at first bump of the key! Thanks again. Was getting very frustrated, now I can fish.

 

[Jiggz]

Re: 1988 85 hp. Odd situation, what did I fry?

Yup, those spade connectors are really villain on this type of wiring. Worse yet they are hidden under the shrink tubes and with only a couple of stands left connected, a cold resistance check will still give a good indication but not with power delivery. Good on you and enjoy her again.

 

[pnwboat]

Re: 1988 85 hp. Odd situation, what did I fry?

Glad you got it going. Happy boating!