pulling wire off #3 plug

[tonycrespo]

force 150 starts well, idles smoothly with water muffs pumping water, but rpms stay the same when you pull plug wire off #3 plug. Compression is good in all cylinders. plug looks as wet as the others. coil is sending spark. I'm puzzled. Your thoughts...

 

[pnwboat]

Re: pulling wire off #3 plug

Are you having any performance issues when out on the water?

Reason I ask, I had a problem with my 1988 125HP, only it affected two cylinders. Started and ran OK at higher RPM's but idled rough and had a tendency to stall when putting it into gear. I could pull either #1 or #2 plug wire off one at a time and idle didn't change. These two cylinders had spark, but it was really hard to tell if it was a good strong blue spark because of the bright sunlight when I was checking. Turned out to be a bad CD module for those two cylinders.

 

[tonycrespo]

Re: pulling wire off #3 plug

out on the water, I have trouble getting up on plane, and when I do, I can hear and feel a surge of power, almost like #3 is firing every now and then

 

[pnwboat]

Re: pulling wire off #3 plug

What year is your motor? Do you have the serial number? Year determines what type of ignition system.

 

[tonycrespo]

Re: pulling wire off #3 plug

I did some research on type of ignition system. I have the Presolite System. (Blue coils and boxes).
I had her out last night. She fired up and ran smoother since I installed new plugs (Flat fire NGK's), but I'm not sure if I am getting peak performance. My top speed used to be 39mph and now I can only get up to 34mph.
No. three control box has a extra output lead so I tried switching the trigger output wiring to this side and did not seem to make a differance.
I had a volt meter on my battery to monitor charge voltage and saw 13.54 volts while cruising around. Is that good?

This is a great web site by the way...

thanks

 

[pnwboat]

Re: pulling wire off #3 plug

I have the same Prestolite ignition on my motor. 13.54 volts is within specs. Try some simple basic checks first. Compression, timing to see what you come up with.

Also check the ground connections on all the coils, and the ground from the coil mounting plate that goes to the block. There is usually one tiny wire from the mounting plate to the block. I added an additional one to make sure I had a good connection.

I know what you are going through. I had some performance issues with my motor. Not enough to prevent me from using it. I knew that there was something wrong but took a while before I got it all sorted out. Very aggravating though. Start out with the easy basic checks first before you start throwing money at it and replacing expensive ignition components.

 

[tonycrespo]

Re: pulling wire off #3 plug

I'll keep diagnosing before spending money. The ground checks are a good start. I'm wondering about my fuel quality as welll. I have a half tank of gas (20 gal/40 gal capacity) but it's from last summer. I did not add anything to it for winter storage. Have you ever tried Seafoam?

Your thoughts

 

[pnwboat]

Re: pulling wire off #3 plug

Storage conditions ( storage period, temperature, humidity etc.) really determine if any additives are needed. They're not always required, but it doesn't hurt to use some just to be sure. I've used Seafoam many times. Works great full strength for freeing up stuck rings that are carboned up to restore/increase compression. Haven't seen any difference by adding it to a tank of gas, but based on what I see from de-carboning rings it is probably good as a preventive measure as long as you don't over do it. Creates lots of smoke if you do.

Perform those basic checks grounds, compression and see what you come up with.

 

[tonycrespo]

Re: pulling wire off #3 plug

I have a low spark problem on my force 150. I switched coils 1 and 3 and still have a weak fire on no.3. The CD module has a spare lead coming out of it. Can I use this unused side of the cd unit and what wiring must be changed? The trigger signal, what else?

Your thoughts
Thanks

 

[pnwboat]

Re: pulling wire off #3 plug

You can test using that method, but you probably also need to move the stator wires in addition to the trigger. Take a picture and or write down the color of the wires and corresponding terminals they're connected to before you do anything.

It's looking like you either have a bad CD module or trigger. Trigger wires should read around 54 ohms when disconnected from the terminal block.

One other gotcha....The CD module that is not producing enough spark may not in fact be the bad one. It could be one of the other CD units affecting the operation of a good CD module. All three CD modules are tied together by the Black/Yellow or White wires (depend on what year). These wires are part of the Kill Circuit when you turn the ignition switch off. It gounds these wires to kill the signal to the CD modules.

 

[tonycrespo]

Re: pulling wire off #3 plug

I checked that already by removing the kill wire from the suspected cd and still a very weak spark at the plug.
I tried switching the trigger leads and the lead that goes to the coil but I did not switch the feed lead coming from the stator. Must that be moved as well?
I'll check the ohms readings too.

thanks

 

[pnwboat]

Re: pulling wire off #3 plug

When I was having issues with my Prestolite system, I tried moving just the trigger leads. I theory it should work. For some reason, I can't remember all the details because I did so many things...but my tests were inconclusive. You can try it by just moving the trigger leads and see what you get.

If no difference, swap all the wires (trigger, stator, coil) between the 2nd and 3rd CD module. If the problem moves, then I would suspect the original CD module for #3 and 4 cylinder is bad.

One other thing, the stator leads should read 680 - 850 ohms between the blue and yellow or brown/yellow and brown/blue wires depending on year.

 

[tonycrespo]

Re: pulling wire off #3 plug, may be fixed!!!

Re: pulling wire off #3 plug, may be fixed!!!

Yesterday while holding the #3 plug wire with insulated pliers to see if I made I made a differance, I felt the most wonderful thing, a 20,000 volt bump on my arm when the #3 coil fired.
I switched all the ignition wiring to the un-used side of the cd box.
Steps
1- switched coil lead
2- switched trigger leads
3- switched stator feed line to cd box

The weather is crappy today, possible rain but I have to go on the lake to
check it out.

wish me luck..

 

[pnwboat]

Re: pulling wire off #3 plug

Good luck! Keep us posted.

 

[tonycrespo]

Re: pulling wire off #3 plug

well yesterday was the first chance I could get out and try my motor.
I warmed her up, gave her full throttle and up on plane she went, as I continued on a short while when she started to bog down and to make a long story short, #3 plug is dead, no spark AGAIN!...
I'm going to check the kill curcuit on this CD again. While checking ohms and voltages I noticed that all the bolts holding the cd packs did not measure anything on a ohms meter except on bolt, this bolt was showing that it had ground while the others showed infinity. this bolt holds the cd pack for #3 coil. Are the cd's supposed to isolated from the mounting plate?

searching for a solution...

 

[shawpdx1]

Re: pulling wire off #3 plug

Im having this same problem with a 1985 85hp force had spark yesterday now its gone. If I wire according to book I loose spark to #3 Ive check and rechecked wiring for grounding Ive pulled the fly 100 times if not once. frustrating knowing 1 cylinder is keeping it from running. guess I'll pull out the credit card and buy all new parts don't know what else to do. fix it and sell the thing get a johnson or a mercury

 

[shawpdx1]

Re: pulling wire off #3 plug

Tony how did you switch the leads? to use the other side of the CDI Actually whoever wired mine has the red wire plugged into the box so I think Im wired for the orange and running off the red I did try the orange and no spark off that either

 

[pnwboat]

Re: pulling wire off #3 plug

The CD modules are isolated from the mounting plate. I suspect that the bolt you are checking has a ground wire attached to it on the back side of the mounting plate that runs to the block. The mounting plate itself is grounded to the engine block with a wire. This is an important ground connection as the ground connection for all the coils connect to the mounting plate which in turn continues to the block via this wire. I added a second wire on mine from the mounting plate to the block just to be sure to maintain a good ground connection.

Anyways back to your problem. Bottom line....switching the wires on the CD modules did not have an affect on your problem. Normally that would point towards a problem with the stator or trigger but before you go there do as you mentioned and try to isolate the CD modules and kill circuit wires. What you want to do is to see if you can restore the spark to #3 cylinder by removing the kill circuit wire from each of the other CD modules one at a time.

Did the stator and trigger windings ohm out OK?

 

[shawpdx1]

Re: pulling wire off #3 plug

Thanks Im not sure how to check the stator. how is this done? and checking the trigger. the strange thing is I had spark from it 2 days ago I switched a wire of course can't remember. what wires are the kill switch? I bought this motor this way so no history but all the vitals are good 135psi in all 3 cylinders BAFFELED

 

[tonycrespo]

Re: pulling wire off #3 plug

PNW, I'm not sure how to take ohm readings on the trigger and stator.
But I will check the back of the mounting plate. I too added a second ground wire to assure good ground.