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1994 Johnson 50 - Idle issue, dies in neutral

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First time poster, and first attempt outboard repair outside of simple stuff. Pretty serious DIY'r so I just kinda dove in...I need help diagnosing my issue from the collective wisdom here; (please!?). I've been scouring the internet for a long time reading/learning and this is still kicking my butt. Butt it's become an obsession now to resolve! Bare with my details (hoping it may help someone researching, and provide context too).

94 J50TLERE on a Tracker pontoon that I inherited. Over time the ability to idle just worsened, Now, it will die anytime it's returned to neutral. It will run 11-1200 rpms or above, and will rev to redline or above (5,500 rpms) I've verified - stopped in fear. I carried it into a repair shop for diagnosis, they advised it's running on one cylinder, and needs a power pack. I replaced that with a CDI one, rebuilt the carbs (new it probably needed it anyway), and replaced the plugs. Same symptoms - fires enough to disengage starter but won't idle without applying throttle. Also, I'm doing all of this in a big trough, so it has back pressure.

De-gunked with the "whatever it's called" method of concentrated Seafoam/1 gallon of fuel -no change, still no idle.<br><br>Swapped plug wires, verified ignition system is good (I'm pretty confident anyway - coils, power pack, stator,timer base, etc. voltages,ohms, continuity ~normal). I was convinced it's the ignition breaking down some where, and was "weak" at low rpms, thus the no idle condition. Nope - same status...

Moves to fuel - read repeatedly it's idle circuit issues...pulled carbs apart again, wire probed all the circuits, soaked and compressed air. Blew out the fuel lines, verified (visually) fuel pressure is good (pulled lines individually and it rev's well); Found fuel solenoid/primer top was cracked. Replaced (thought sucking air, low pressure at low rpms) - still no idle. Starting to seem starved for air, slow out of gate, but then catches up and rev's well then.

Moved on to air - Pulled intake to check leaf valves. See light under a few of them, so I replaced them with CCM valves. Throttle response is greatly improved, real snappy, thought I had fixed it (can make it idle with slight throttle forward), put cowling and all back on. It dies at idle with cowling on...

So, now onto the Exhaust side, as I've noticed through this troubleshooting that smoke is coming out of shift linkage hole (has been all along, but didn't really connect the dots), so I dropped the gear head and foot/boot. Now I'm lost...I want to think it's that the lower grommet is/has been my primary issue all along as it's floppy loose and has obviously been leaking, but I'm unsure. While I have it apart, I'd to just "fix it", so here's where ya'll come in. I don't know how to read the signs of what's happening here. Just don't understand it enough. Even like what's water/exhaust and which hole ha! Not sure what it's telling me that one side is "clean" while the other is dirty? Or is it leaking from the top (power head exhaust gasket) or leaking from the bottom (lower unit grommet) and spraying exhaust up inside?

See pics below...Thanks for any and all help here!

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I have never seen anyone take that apart on one of these motors.----What are the results of a compression test on this motor ?----Will it keep running/ idling with cowling off ?
 
Marina repair said it was 130# and 135#, respectively. My home sets reads 110#, 115#. It was "spitting" out one of the carbs before I replaced the leafs. Leafs fixed that issue, and it pulls pretty even across them both now,slightly off I say due to the compression (or my suspected exhaust leak). My ignorance is part that is exposed part is the muffler (?), and I thought it could be leaking there or the power head. I ordered a replacement grommet (on the way) to replace the bottom seals (very loose), but not confident it's really going to improve anything.

Yes it will idle with cowling off, but not without advancing the throttle some (and crack open the butterflies) to make it "idle". Even with that forced idle (11-1200 rpms with throttle advanced), it still dies when you put the cowling back on though. It slowly (20 seconds or so) snuffs itself out. So it only idles with the cowling off and the throttle advanced. My goal (hope) is to get it to idle with proper link/sync settings and on the idle circuits. have been suspecting it's not "sucking" enough for some reason, but don't think it's compression related. But not sure...

(thanks for the help already, btw)
 
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Another tidbit, before I replaced the leafs, it would start and run (throttle advanced/cowling off) on mainly one cylinder - like 90/10, then after it idled for a bit and warmed up, or you increased fuel/rpm the other cylinder would come on, and it'd kind've jump RPMs. that was associated to that spitting out the carb cylinder. Leafs seemed to have fixed that. So it's like I've been slowly ticking away at and ridding of symptoms, but still yet to solve the problem of idling in neutral without some throttle help.
 
Well---I think you are barking up the wrong tree on your motor issues.----I would pull the cylinder head and have a look in there at cylinder walls.---Head gaskets are cheap and just a little effort.
 
sounds good, hate to hear it but I appreciate it. At this point, I'm thinking it'd be wise to just "fix it" while I got it torn down. I'm actually getting pretty good at snatching parts off this thing :)

so your suspicion is rings/compression/head gasket? And if that is not it (walls clear, head gasket good), then it's bottom powerhead gasket? Like, that'd be about all that's left on the air side?

also, overall, is it a worth while motor to invest in? Meaning if I can do the repairs myself, so part cost alone, it's worth fixing and investing a few $'s into? I've been struggling with the engine value/expected longevity...and whether it's worth it or not? Kinda had this limit of $500 or less of being worth it. Just don't know much about the engine itself. All I have to compare to is a late 80s model 30HP Nissan/Tohatsu I have on my Jon boat that just runs. :) Love that thing.
 
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Well----The bolts that hold the powerhead on are out.-----So I think you need to change / inspect that gasket.
 
What's making you think that, experience or something I described (just curious)? So, your thinking it's compression related (head gasket, rings, cylinder wall scoring) or powerhead gasket (leak)?
 
Sorry------My outboard repair experience goes way beyond replacing sparkplugs.----Bought 4 motors just like yours last year for parts / rebuilding.
 
Head gasket, and powerhead gaskets both seem ok (I think)? I see no obvious burn through or leaking that I can tell? There is some minor scoring on the top cylinder wall, and you can see where it had not run on that cylinder by the dis-colorization in the head. I think that is from the previous failed power pack. I wonder if that is what caused the cylinder wall scoring? You can't really feel the scoring finger nail or tip, but you can see them in the pics (see below). Does that make it a candidate for a re-ring/hone?

Whatcha think or recommend? Appreciate the help ;)

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Compression test is the # 1 step in outboard trouble shooting.----As in post # 2 and I say it all the time.------Head gaskets are cheap compared to all the work done on this motor.-------Your motor needs to come apart for repairs to one or both cylinders.-----Trouble shooting is a lost art it appears.----Post pictures of the top piston when you have this motor apart.
 
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I hear you, I enjoy finding root cause and knowing I accurately diagnosed the true issue (vs. guessing). that's what is getting me here with this one, compression is 90# or above or both...???

I understand what your saying here though, by getting to the actual pistons/rings and getting them out (due to the scoring), so you "know"... And you don't until they are out (and you can see them). If not, your still guessing... ;)

Do you have to split the case to get them out, or can you get them out via the intake?
 
Sorry-----You are still guessing.------Motor has to be split in order to do a proper job.-----I do not have enuff fingers & toes to count how many times I have seen this kind of damage.----A good motor like that shows 140 PSI on my gauges.
 
Gotcha, thanks. Don't like it, but I get it :)

Do you think it's a likely candidate for a re-ring (your experience), or does normally require boring/over-sized pistons? Just trying to gauge cost for the repair.
 
Once again----I say that putting new rings on those used pistons is not a good idea.-----Take it apart.---Inspect everything , before spending any coins on it.------One other thing to consider.----The lower units are not robust on these and I would have a look at pinion and forward gear before spending time and coins on it.----Experience counts.
 
Thanks for the grin Rwbutler! :)

With all the VRO removals I've seen, I've speculated that thing may be on the way out. I think it's the result of running on one cylinder before I got it (i.e the scored one), which I initially fixed with the bad power pack.

I'll be back once I get it tore the rest of the way down, and decide what I'm gonna do,and Bust Out Another Thousand (boat...)
 
Meaning, that it can't score the cylinder wall then from lack of combustion in that cylinder? My thinking was poor/no combustion caused poor lubrication in that cylinder? It wouldn't oil right then, I assumed. It also ran poorly on that one cylinder at low RPMS and spit it out it's carb until I replaced the leafs too. So all-in-all I thought it simply had poor lubrication in that cylinder. I also don't have the piston out yet to see if a ring may be broke either.

I'll be back with some pics once I get'r tore down some more, I just have the powerhead on a table still.
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No spark in that one cylinder would not score that cylinder !----Your statements assumptions in post #20 is just more proof to me that lubrication in 2 strokes is not well understood.
 
JMO.....Stop, put it back together and sell it as running parts motor and get a 3 cylinder 50 Johnson to replace it. The lower unit if good is worth more than the whole motor.
 
No spark in that one cylinder would not score that cylinder !----Your statements assumptions in post #20 is just more proof to me that lubrication in 2 strokes is not well understood.
Totally agree,i would go so for to say that they know nothing about fuel systems,ignition system. Most have never read an owners manual.
 
Got the pistons out... this is the top one.

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Walls are scored more at the bottom of the cylinder. You can feel the scoring more at the bottom vs. the top of the cylinder, but it does look alot worse than it feels. but booo, regardless. Top piston definitely took the brunt of it, which I guess is a plus? :)

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Now to track down a machine shop that does power heads and see what the damage it. It is time consuming dismantling these things I tell ya! Got slowed down tracking down a 12pt 5/16 socket for the rod cap bolts :) Finally did found one after looking at 4 stores. Then with the help of the bench grinder - it fit perfect.
 
More pics (cuz pics are always good)... Looked alot better than I thought in there. Does the top rod cap color difference mean anything? I thought it might be a sign towards what happened? 2nd pic for the journals.

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