1985 Force 85 hp running rough

sirrob281

Cadet
Joined
Jul 26, 2007
Messages
17
A few weeks back we were out on the boat and I went to take off and the engine hesitated like one of the plugs were fouled up. Its been several years since I have had any plug issues so I didn't think to much of it so I went and replaced all 3 plugs. To my surprise that didn't fix the situation. It has actually getting worse. It starts on the first turn with no issues and idles good, but once you begin to give it gas then it would start "missing". It would usually catch and go after a few misses but now it just keeps missing. I don't know if "missing" is the right word but it feels like it was going to take off the stop then catch, then stop. My first thought is the spark plug wires/coils.I am thinking that maybe one of the boxes is arcing under load. I know the 3 wires have never been changed. I do get a spark from each box when starting with no load. If it's not that then the 2 boxes or even the stator. Has anyone had this issue? The motor has run great for so many years I figured someday something was going to come up sooner or later.
 

sirrob281

Cadet
Joined
Jul 26, 2007
Messages
17
Re: 1985 Force 85 hp running rough

I thought about the water in the gas when it first started but I have filled the tank a few times since and put in some moisture remover for the fuel, that would be wayyyyy to easy,lol. The diaphragm might be something I might look into next. I have 3 coils on the way and will see what happens. The odd thing i found was that the top spark plug and the bottom spark plug were both very clean with no carbon marks at all while the middle one did have some on it which makes me wonder if the top and bottom were even firing. I willlet you guys know what happens next.
 

sirrob281

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Joined
Jul 26, 2007
Messages
17
Re: 1985 Force 85 hp running rough

OK well here is what we did.
1- replaced coils all worked but the 1st coil. Hooked the first coil to the another CD box and then that coil sparked.
2- Rewired the CD box to 3rd CD box wiring and then the CD box worked.
So the wiring coming out of the trigger seems to be causing the issue due to process of elimination. Before I begin the process of replacing the trigger does this make sense? I did come across some broken wires and wires were breaking has we were doing our test so this is probably the issue through out the trigger ( the wires are so thing and its over 20 yrs old)
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,924
Re: 1985 Force 85 hp running rough

If I work on any Force/Chrysler ignition.
The first thing I do is replace ALL the connectors on the stator/trigger.
Had a problem with a motor,turns out the trigger leads were broken under the heat shrink.
Would work great when the throttle was moved and not at an idle.
 

sirrob281

Cadet
Joined
Jul 26, 2007
Messages
17
Re: 1985 Force 85 hp running rough

Ok, replace the trigger today and that did the trick. All cylinders firing and engine starts nicely. Now for some odd reason the engine idols to fast. I am going to adjust the throttle linkage tomorrow but kinda can't figure out why this happened. The throttle arm doesn't come back far enough when going into neutral.
 

sirrob281

Cadet
Joined
Jul 26, 2007
Messages
17
Re: 1985 Force 85 hp running rough

Thanks for the info! Well before i get involved with the adjustments I decided to check the compression just to make sure there is some thing else going on here because I keep hearing what might be the carbs backfiring or knock coming from the engine. No pattern to this noise but very concerning. The results were 115 on the top,and the middle and bottom cylinders were both 120. Enough to be concerned over?
 

foodfisher

Captain
Joined
Feb 18, 2009
Messages
3,756
Re: 1985 Force 85 hp running rough

"The results were 115 on the top,and the middle and bottom cylinders were both 120." Huh? Anyway, the numbers are close enough.
 
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