Johnson 110 occasionally losing spark one cylinder (I think), what to replace?

[leaky]

Hi,

I have an 89 Johnson 110, crossflow v4. About 4 years ago I rebuilt it, had some woes with initial setup and one issue with a spark plug boot that was cracked, grounding out 1 cylinder anytime the cowl was on , and another weird starter thing, but other than that has been pretty smooth sailing.

The last couple trips I've noticed what I'd describe as a change in the sound of the engine on occasion while cruising, sorta the tone of it dulling a bit then returning to normal with no apparent change in rpm/speed, also although it's always had a tendency to load up a bit at idle it's been worse about it, and last a couple times I've noted a bit of on/off sort of hesitation or surging - nothing most people would notice but knowing the boat/engine it struck me as different.

Recently, checked fuel supply stuff - not a drop of anything in the water separator, fuel is clean (and it ought to be, I keep up with it).

Today after about an hour and a half of use it just randomly would not go over ~2500 RPM, when at full throttle normally this boat jumps right up and it's > 5000 RPM, tried working the primer bulb, tried the choke (which made it worse), and also it was having a terrible time idling - lots of miss and uneven running, hard to keep at a low RPM but ran alright at ~1500-2000..

Got home, went through normal routine - compression, on my gauge 95 to 100 each cylinder (which is a bit up from the 95/cylinder it was when I rebuilt it ~4 years ago), reading plugs shows all on the fairly clean side of "normal" but the #2 cylinder (2nd from bottom by my count, not sure how they count them) is notably cleaner than others, wet with fuel - would've bet a weeks pay there would be no spark on that one. Nope - strong spark, jumps about 3/4 inch no problem, same as others 3 cylinders.. Hmmm... For the hell of it checked resistance on coils, all the same..

Brought it to the lake to trouble-shoot tonight and the problem is gone - actually was running fast or faster than it ever has, looks like I need to consider going up in prop pitch because I could go > 5500 RPM if I wanted. Ran around and around and around, hole shot, hard run, cruise speed, nothing going wrong now...

Sooooo I figure what I most likely got here is some ignition problem that can come and go until it fully fails? Any recommendation on what to check or do? I'm thinking of checking resistances, if nothing found, starting with a coil, replace it, if problem returns pick another part etc.. etc..

Thanks in advance!

Jon

[JoshKeller]

i just went through the same issue with my 110 - it would run GREAT the first run of the day, but then would change sounds and lose 150 rpm after you restarted the motor after fishing. it turned out to be the powerpack failing after it heated up.

[leaky]

i just went through the same issue with my 110 - it would run GREAT the first run of the day, but then would change sounds and lose 150 rpm after you restarted the motor after fishing. it turned out to be the powerpack failing after it heated up.

Thanks - that's good news because in shopping around for parts last night I saw a new power pack was $100, coil $30, and figured I'd knock half the ignition components out for cylinder number 2 that way.. Also I always hated the leads on that power pack, never could find anything wrong with them but were just really old wires I constantly felt like I needed to inspect for cracks.

Stator & trigger are more expensive parts, be nice to have a more definitive answer before going that route but hopefully it's just that, power pack or coil.

[leaky]

Haven't got a chance to do any real trouble-shooting, power pack showed up today but haven't had time to install that either.

Went out fishing tonight and got a little more info about what's going on though - engine ran fine first hour or so then, similar to what happened previously, on a cruise like somebody flicked a switch the sound changed and power decreased - still was holding the boat on a plane but I could tell things went south right at that instant. Took it off a plane and tried to get going again, no dice - can rev it up > 3000 in neutral but there's just not enough HP there to get > 2500 in gear and runs rough.

Interesting observations - I have temp gauges on both cylinder banks, port bank runs at a normal temp, starboard bank a very low temp and it was the starboard bottom cylinder I swore must not be firing last time I read the plugs.. Even holding your hand on the heads it's very obvious that side is much cooler than the other... However I put a timing light on it when I got back to the dock (brought one since it's an easy way to check presence of any spark) and there is consistent spark on all of them.

A friend of mine who's a mechanic was with me and swore it's gotta be ignition too but not so definitive from the timing light, of course a spark tester would've been the right tool for this test.

Sooooo what I can say for sure is - #1 impacts one or maybe both on the starboard side and prevents firing #2 if it's indeed spark (and man it's hard to fathom this could be anything else to happen so suddenly) it's weak spark not no spark..

I'm a little suspicious about charging now - was not quite getting voltage sufficient to kick my ACR's on (engine battery showed 12.4 when I checked at 2000 RPM), which will combine with this engine (believe it has a 35 amp system), however was not checking them when I was running at a cruise RPM rather only looked at them when I was limping at 2000 RPM. If a charging issue is present, of course it could be the stator - gotta go at this right, which I think I can tomorrow, with a multi meter - will shotgun the coil and power pack as I've got them now anyway and while I'm at it trouble-shoot other components.

[JoshKeller]

if you dont get it figured out with the parts you have on hand, i have spares of every electronic part on that motor. pay shipping both ways and youre welcome to borrow any of them to test

[leaky]

if you dont get it figured out with the parts you have on hand, i have spares of every electronic part on that motor. pay shipping both ways and youre welcome to borrow any of them to test

Wow - thanks for that!

I've always wanted to give the electrical stuff a refresh, as I did the rest of the engine, it's one of those thing I just never got to. Ideally what I'd do is hunt for lightly used more recent parts that cross reference, but aftermarket/refurb/old-stock isn't all that expensive either on these (one of the beautiful things about a V4 OMC, lots of parts).

Provided I can confirm it's definitely electrical, if I end up spending an extra $350 in new parts I'm OK with that - the stuff that's on it all appears original, quite aged compared to the guts of the engine. But I would like to somehow find better confirmation I got an electrical problem, sure seems like it, but has not been exposed in testing - hopefully I find something later.

Two other things I also have been considering, #1 if somehow it's overheating on the side I think is "good" - sure doesn't seem that way as neither the overheat sensor, nor my temp gauge, nor my hand seem to feel that way (if I can hold my hand on the head it isn't too hot), but in the back of my mind I know if you heat them up enough they can run bad.. #2 if somehow I got a water leak into the cylinder that only exposes after an hour or two of runtime yet seals itself back up after sitting for a couple hours - not that I see evidence of that or that it makes sense either. I do know there is no external leak as I've checked that (ie checked for any sign of ignition parts getting wet when it happened)... Neither of those situations seem likely but trying to consider all possibilities. What I can't hypothesize is how a fuel or reed problem would pop up only after such runtime, then self heal - so not going to go down that path other than I am going to pull the cover off the carb throats just to make sure there isn't anything floating around in there (had an oak leaf once get into the carb throat on a merc 115 I had, caused all sorts of chaos ).

Jon

[leaky]

Soooo - while being attacked by mosquito's, ticks, and threatened by various animals, I got into some trouble-shooting..

#1 observation - I've got two books on these engines, one says stator leads should be 475 to 625 ohms, other says 485 to 635 ohms.. My stator tests at a consistent 478. Hmmmm..

#2 read plugs - now, which is a completely different state than the plugs where in other times I've checked them, all plugs are on the fouled side of normal, with the #2 still being a little cleaner than the others.

In attempting to check trigger resistance my manual shows my trigger as being a 4 wire, with dual power packs, when in actuality there is 1 power pack and 5 wires - year and all that is correct it's just the repair manuals (both of them) do not seem to reflect any of these single power pack 5-wire-trigger systems... Also, since it's written in such an odd manner, I can seem to figure out exactly what they want you to do - can anyone translate?

Separate the 4-prong connector. This is the connector that leads from the power pack to the timer base.

Insert one end of a jumper into all 4 points of the connector half which leads to the timer base A, B, and C. (Note the female side of the plug is on the power pack, but the leads are labeled on the plug so that is known, and by 4 points I assume they forgot D)..

Connect the test leads of the ohmmeter to each of the jumper wires to A and B. Observe the meter reading. (Here I and below I can't figure out what they mean exactly)

Disconnect the ohmmeter lead to the B terminal and connect the test lead to the C jumper lead.

Disconnect the meter lead to teh B jumper lead and connect it to the C jumper lead.

They say in all these tests you should see ~40 ohms, by using one lead on A or B, and checking all other pins, I see ~80 or ~40, depending which pin. Gotta dig up a spare plug to use for testing, or more female pins I can use to rig up for this test, but I can't figure out exactly what they want you to do.

[flabum1017]

If you have CDI power packs, check the ground wire crimps.... I went through several of them where they crimped them against the insulation instead of the wire..............

[leaky]

If you have CDI power packs, check the ground wire crimps.... I went through several of them where they crimped them against the insulation instead of the wire..............

Thanks for that - what was the symptom?

I put a new power pack on it today, and also found a decent deal on a new (OMC not aftermarket) stator - $120, which I ordered today.

Started it up after putting the power pack on there today - runs OK, hell maybe it runs a little better even, but not going to know anything until I can get through a whole trip running right. Did seem to be idling better than it ever has and had a better snap to it upon revving in neutral but been fooled before and could be imagining things .

Jon

[Jimmybar]

If you have CDI power packs, check the ground wire crimps.... I went through several of them where they crimped them against the insulation instead of the wire..............

check all the earth points . sounds like a high resistance there . OMC recommended earth points , in particular coils .

[leaky]

check all the earth points . sounds like a high resistance there . OMC recommended earth points , in particular coils .

Sorry can you expand on that?

I assume earth points are the various ground straps that connect various things together?

How are the coils related?

And how would such a problem arise after so much use and then disappear once things cool down?

thanks!

Jon

[JoshKeller]

Sorry can you expand on that?

I assume earth points are the various ground straps that connect various things together?

How are the coils related?

And how would such a problem arise after so much use and then disappear once things cool down?

thanks!

Jon

this sounds EXACTLY like my issue i was having. i think the powerpack will solve your issue

[leaky]

this sounds EXACTLY like my issue i was having. i think the powerpack will solve your issue

Thanks and I hope so! Has a new powerpack on it now and at a minimum did not seem to cause any new problems .. Going to get it in the water next day or two and see how it goes, best way to test it seems to be just to go fishing.

Am a little concerned about the stator though as it tested only 3 ohms over the minimum spec from one book I have, while with the other books spec it was actually out of spec by being under by 12 ohms. Whatever the case have one of those on it's way now and it did not break the bank either.

Jon

[JoshKeller]

ive had different multimeters read different ohms just like compression tests read different. almost all of them that ive tested have been on the lower end

[Jimmybar]

Sorry can you expand on that?

I assume earth points are the various ground straps that connect various things together?

How are the coils related?

And how would such a problem arise after so much use and then disappear once things cool down?

thanks!

Jon

the higher the temperature . the high the resistance
Earth points are often overlooked , changing components does fix the symptom but in some cases not the problem, if you have checked the ohms resistance and its within limits , there's a good chance its ok , however the earth connection is just as important for reliability . have a look on the mounting of the POWER PACS you'll find a metal insert on one or more of the bolt holes , for a good earth the mating surface should be cleaned to metal . you can use star washers of a metal that does not react with adjoining metals . or spray with a sealing agent like silver paint . grease . soft seal . what ever turns you on . the coils are the same. there will be a metal mount on a bolt hole its very important to have this right . then check the earth strap between the head and block [ if the coils are mounted on the heads ] then the block to the CDI unit from there to the earth on starter motor . Its a cheap fix . often coils burn out because the earth is crook .this may not be the problem but worth a look ,,,, hope this helps . cheers