85 Force Cylinder #3 Not Firing !!Puzzled!!

[dkrool]

I first have to apologize for the long post. I figured that I may be able to save some threads by being thorough in the description of my trouble.

I have an 1985 Force 85HP US Marine Outboard on a 16.5' Bayliner Capri w/ Cuddy. My problem (other than the fact that I have a 1985 Force motor) is that the motor is not firing on the #3 cylinder. I have come to this conclusion by pulling each of the 3 spark plug wires. When either the #1 or #2 are pulled, the motor begins to run roughly and will eventually stop running. When I pull the #3 plug wire, performance is unaffected.

I must note that occasionally though be it rare, the motor will slowly seem to begin sputtering and catch up with itself and run very well to speeds of nearly 30mph. This is shortlived though because when I throttle back to idle, then advance the throttle again, it usually begins to run poorly. By poorly I mean, it runs consistantly, firing on only the #1 and #2 cylinders only allowing me 10 to 12 mph. If I were to give a percentage of how often it runs well, it would be below 10% of the time.

My compressions are as follows
#1-113
#2-120
#3-125

Here's a list of what I have done:
Replaced Both Power Packs.
Replaced all Three Coils.
Rebuilt all Three Carbs.
Changed the Spark Plugs.
Replaced the Thermostat.
Replaced the Water Pump

I have switched The #2 and #3 Carbs hoping that it was a carb problem. The problem remained with the cylinder and not the carb.

I have switched the 2 power packs. The problem remained with the cylinder.

I have visually inspected the intakes of all three cylinders and see no abnormalities.

I have been shocked when pulling the plug wire off, and I have pulled the plug out and seen spark. I know that there is spark at the plug! One thing to note is that The plugs in the #1 and #2 cylinders appear to be oily with normal appearance. The plug on the #3 cylinder has very little carbon on it and has places that are still shiny bare metal.

I have adjusted the carbs and need to note that I can notice change when adjusting the #1 and #2 fuel/air mix. I can adjust the needle for the #3 fully in each direction without any change in performance.

Any thoughts would be appreciated.

 

[Chadricco]

Re: 85 Force Cylinder #3 Not Firing !!Puzzled!!

I just (hopefully!) finished troubleshooting ignition issues on a 1988 version of this engine --- thanks mostly to this forum! Thank you all!

It sounds like your stator output voltage may be low. The stator produces two sets of A/C voltage, one for each CD box (power pack) which converts voltage to D/C then feeds the coils when prompted by the timing trigger. Anyway, lower than normal voltage may still produce a spark in open air, but its not strong enough to ignite fuel under pressure.

Test your spark strength if you can get your hands on a spark tester (fixture that forces the spark to jump a larger gap). Alternately, remove all 3 plugs and ground them all as required --- I used 3 jumpers with alligator clips. Crank the engine while observing all three plugs. Are all sparks equally bright snappy blue? If yes...... then I hope someone else has an idea!


Good luck,
-Fellow Force Fixer

 

[dkrool]

Re: 85 Force Cylinder #3 Not Firing !!Puzzled!!

I found this after I placed my post. It's funny, I searched for a couple of hours before placing the post to try to keep from asking a duplicate question.

"These engines have one itty-bitty ground wire coming off the electronic mounting plate to the block and all components are grounded to the plate. Before you go crazy, run a separate ground wire daisy chain fashion from all three coils and both electronic boxes to the terminal block on the other side of the engine. double check the ground for #3 coil. if all grounds are OK, since you have replaced all other components, and since it only happens on #3 cyl, then the trigger is a suspect. Check the trigger connection with only two wires, (that's #3) and check the wires under the flywheel: these wires move with the trigger and it is not unlikely that one of them broke. possibly internally from flexing. I don't remember the resistance, but the triggers are coils that produce about 1/2 volt signal voltage. So you should be able to check #3 against the other two with an accuate voltmeterwhile cranking the engine. If you show 0 volts at the connector, there's your culprit.
FYI:1 and 2 cyl are fired by the first box, 3 is fired by one side of the second box. So, if one half of a box fails, use the good half on #3 and the good box on 1 and 2. save a little money that way. White wire from boxes is shut off, black wire is ground. both connect to ground when engine is shut down. However, if you have a bad ground on the black wire, the box will not fire the coil."

 

[dkrool]

Re: 85 Force Cylinder #3 Not Firing !!Puzzled!!

I have dug a bit deeper today. I was checking voltages in a few places and found something a little disturbing. First of all, I need to mention that the voltage coming out of the trigger was nearly 50volts as far as I can tell with the engine at fast idle. I am left to presume that the trigger is working properly.

I did notice that I had roughly 30 volts from one point of ground at the mounting plate to a point of ground at the engine. This tells me that I have a direct short, and I am leaning towards thinking that it is from one of the wires from the stator.

Also, are there any recommendations for getting the flywheel off? It's tough trying to keep it from turning and getting the nut off of the top.

Any other thoughts would be helpful.

 

[chitownborn]

Re: 85 Force Cylinder #3 Not Firing !!Puzzled!!

use an impact gun , mine came off no problem

 

[dkrool]

Re: 85 Force Cylinder #3 Not Firing !!Puzzled!!

I did eventually get the nut off, but was unable to easily remove the flywheel. I suppose I can try the 2x4 and big hammer approach because I do not have a flywheel puller handy.

BTW, does anyone have an explanation as to why I have voltage between tow points of ground. It was about 30-31 volts. I would guess a direct short somewhere but have been unsuccessful in my attemts to locate it. I think that I have iscolated my problem to either stator but am just not certain.

 

[tjello327]

Re: 85 Force Cylinder #3 Not Firing !!Puzzled!!

I am no expert, but I do understand how you igniton system works. My guess is the stator too. It creates your voltage and is one of the two components directly mounted to the block. I dont think it is the cdi boxes because of the rubber mounts. Maybe the coils? I would think the voltage leak would be higher if it was a coil. Unlikely the trigger, I believe it runs on low voltage. Stators are prone to shorting out. You can test this if you have a ohm meter. Place your red lead to any stator output (while stator is removed from engine) and put your meter ground to the body of the stator. You should not have any reading. If you do, your stator is shorted.
If you need a used one, reply in this post and let me know if you need one because I have a spare that I will part from. I will give you my e-mail or something else.

Good luck and thanks!
Tom

 

[Tim Wagner]

Re: 85 Force Cylinder #3 Not Firing !!Puzzled!!

Ground is ground is ground.
There should be zero (zero) volts between all ground points.
Meaning they should all be tied together.
If you have a 30V difference that means that particular point isn't grounded.
It has floated up to whatever potential it was able to get to.
You have a grounding problem.

 

[dkrool]

Re: 85 Force Cylinder #3 Not Firing !!Puzzled!!

I took my multimeter in to the store today to get a new one. I used it yesterday for work, hooked it up to a 12volt battery and it read 18 volts. I hooked it up to another 12volt battery and read 18 volts again. I will have to test the grounds again when I can trust my multimeter.

 

[dkrool]

Re: 85 Force Cylinder #3 Not Firing !!Puzzled!!

I recieved my Clymar repair manual the other day and finally did get a new multimeter. I checked the Ohm's on all of my trigger and stator wires. That checked out perfect as per the manual. I also checked to see if there was continuity between any one of the trigger/stator wires and ground and there was none. I pulled out all three spark plugs and grounded them. I can clearly see that I do not have spark on the #3 spark plug. I do have fire on that coil when switching with a wire from the #1 or #2 cylinder. I do not have a DVA meter as the manual says to use to check output voltages while cranking the engine. Does anyone have any suggestions as to determining voltages with a standard multimeter? Or do I need to find a DVA meter?

Thanks!

 

[pnwboat]

Re: 85 Force Cylinder #3 Not Firing !!Puzzled!!

Sounds like it might be the stator, but before you go there check the connections for the stator and trigger wires on the terminal block. The connectors have a small piece of black heat shrink on them where the wire is soldered to the connector. I lost a cylinder on my 88 125. Turns out that the trigger connector for that cylinder only had a single strand of wire making the connection. It ohmed out fine, but the problem was not visible because the break was hidden by black heat shrink.

 

[tjello327]

Re: 85 Force Cylinder #3 Not Firing !!Puzzled!!

If you remove the #3 stator lead from the terminal strip and switch it with a known good stator lead, and you pick up spark on #3 cylinder, you just proved everything else for #3 is working. The onl thing you changed is the stator lead. I had the same problem and didnt have a DVA tester so I tried this and found that my #3 stator output was bad. Changed stators with a Ebay one and it fixed the problem. My #1 also was not working and this test didnt make it pick up spark. Ended up being the CDI box for #1.

 

[chuckz]

Re: 85 Force Cylinder #3 Not Firing !!Puzzled!!

Read Tim Wagners reply again. You have a grounding problem. Initially you were getting shock from #3 now you say it has no spark. Not possible. Where were you grounding the plugs? The entire engine block should be ground. I installed a separate ground from the cylinder head to the ignition plate. I did that because there are two (2) gaskets between the plates the spark plugs mount in and ground. It did not seem like a good grounding scheme. My engine ( 1987 85 hp) fires up first shot without choking. I know I have hot spark.