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STUMPED 1999 Johnson J25R3EEM OIS

S

Shawn070

Member
Good Afternoon Everyone,
I've been trouble shooting this motor for a week or so now. It really has me scratching my head. It runs but it constantly back fires (lean sneeze) through the carbs. And the only way it will idle is if you feather the choke and leave the choke half pulled. It will come off idle and sounds strong when revved a little. I have fire to all three plugs, Compression is 115 evenly on all 3. Carbs are Soaked, Cleaned and rebuilt with new floats, Idle air screws set at 1.5 turns out. I've ohmed the stator and it checks out. I have some help coming to help me read the meter while I pull it to read the voltage with the DVA connected. I did pull the flywheel and checked and cleaned the optical sensor. The wheel under the flywheel looks good also with no damage. Any thoughts on this one. I haven't had too much experience with these OIS motors other than normal maint. Any Thoughts?
 
????----Have to ask.-------Why do you have the idle mixture screws set at 1.5 turns out on this particular motor ??-----Did guess at that or read it in a manual ?-----If a manual then what manual was that ?
 
I left them at 1.5 turns out after rebuilding the carbs. As they do nothing to remedy the backfiring no matter how far in or out they are. My plan is to fine tune the idle mixture when I can get the motor to idle.
 
racerone said:
So no manual.-----They are not turned out 1-1/2 turns.----They are set to a distance on these fine motors.
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You mean the .390" setting? Yes I have a manual and I also have the CDI electronics troubleshooting manual. Is there any other publications that I need to have before u will offer any sort of assistance? Or will you continue to be Rude to get your post count up? What I'm saying is no adjustment of the idle screws makes any difference at all. Which is why I'm thinking its ignition. Those parts are not cheap to take a guess, or "TRY" as some of your coveted manuals state to do. SO, i was hoping a helpful person with alot more experience with these motors would give me some advice.
 
Good luck with your motor then.----No further help from me.----Post # 1 did not indicate that you know about the dimension.----I have to wonder why you ignored that info and set the needles at 1-1/2 turns out.
 
I have to wonder why when you reply to someone's post on here you come off as Brash with no help at all mentioned. I don't post much but I read this forum alot. I understand with a 21k post count you've been here a while and have probably answered many questions that a manual could have covered over and over. A simple "check the manual" would have sufficed. Not the smart Alec remark you made. I did leave the info out about the initial setting (which that's all it is) in my original post. For that I apologize. I've had the idle mixture screws all over the place trying to cure the backfire or "sneeze" to no avail. Good Day.
 
Had a phone call from someone 1500 miles away on a big island.----Looking for a used stator for one of these fine 3 cylinder motors.-----After hearing his story I coached the man on what to do to trouble shoot the wiring.----He said " thank you very much " .-----I told him I have used , tested stators.------He did not call back to order the stator.
 
racerone said:
Had a phone call from someone 1500 miles away on a big island.----Looking for a used stator for one of these fine 3 cylinder motors.-----After hearing his story I coached the man on what to do to trouble shoot the wiring.----He said " thank you very much " .-----I told him I have used , tested stators.------He did not call back to order the stator.
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Yeah he ordered a new one after you helped him diagnose the issue for free, If you're in the game like that I'm sure you've seen your fair share of that kind of thing. The only outboard shop near me will tell people "bring it in and let me look at it" Can't say I blame him there. I just work on a few here and there for friends. I enjoy it, and sometimes hate it, Like today.
 
I'm continuing to update this thread, maybe it will help others in the future. It seems this motor is not dropping out of quickstart. The timing never falls back to 4 degrees ATDC. It constantly stays around 6 degrees BTDC. If I manually retard the timing by hand the sneezing goes away and she straightens right up. I did notice that the owner has some NGK spark plugs in there also. And for this engine it calls for Champion QL86C ONLY. So, I'll try to locate some Champions. I'm suspecting the power pack may be the issue but at the mid 400 dollar range for a new one I have to make darn sure. The owner says it had a new power pack about 10 years ago. He also is the only owner of this rig. He purchased it brand new. More details to follow .
 
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Correction: The CDI Electronics Guide states ONLY Champion QL86C, However The Johnson Factory Service manual states the following spark plugs are acceptable
Champion - QL86C, L86C, For Extended Idle - QL87YC or L87YC
 
The back firing (lean sneeze) isn't coming from the carb throats. its coming from somewhere behind the fuel pump. Which leads me to believe maybe an intake gasket or an air leak between the crank case halves? For my sake lets hope it isn't the latter.
 
...Shawn070...that sneeze happens in the crankcase...behind the pump...not in the carb.

Yer gonna be working on that motor for some time to come I see..
 
If you pull the primer out and it runs better you have a carb problem that is causing a lean sneeze. By pulling the prime out you are bypassing the carbs and dumping fuel int the crank case. Or are the plug wires on the correct plugs?
 
Sunkinmess said:
...Shawn070...that sneeze happens in the crankcase...behind the pump...not in the carb.

Yer gonna be working on that motor for some time to come I see..
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Copy that. And yeah you are correct on the last part. But its why I enjoy it. I've never had too much experience on these but I'm surely getting some on this one.
 
flyingscott said:
If you pull the primer out and it runs better you have a carb problem that is causing a lean sneeze. By pulling the prime out you are bypassing the carbs and dumping fuel int the crank case. Or are the plug wires on the correct plugs?
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This motor doesn't have a Primer it has a manual choke. Yes Sir, I've checked plug wires and coil wires to make sure everything is where its supposed to be.
 
WOW!! Lesson learned today! I've been a mechanic for most of my life. And well I've always practiced the K.I.S.S principal (keep it simple stoopid). But for some reason I wanted to go to the bottom of the ocean on this motor. I think that from a lack of experience on this particular OMC motor I got overwhelmed or maybe a little intimidated. The ignition system on this bird was a learning curve for me. Anyway I went out there this morning and Continued with the Tune up Procedure in the Johnson Manual. I did the throttle plate synchronization and low and behold it straightened right up and purrs like a kitten. But I have a question. This motor has had its oil mixing unit deleted and she now only has ONE fuel pump. The Port side fuel pump. And while there are no leaks in the system and it has a new fuel line and bulb. The primer bulb seems to go flat, not sucked down flat but the engine runs for a while then starves and dies. I can prime it back up all while hearing the fuel filling the float bowls again. The bulb will pump back hard and she will go again. From my reading one of the two pump was a suction and one was a pressure. And on the parts list there are two different part numbers for the pumps. Which one is which? I can't really tell from the parts diagram which one would work for this motor with out the oil mixer.
 
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Shawn070 said:
Copy that. And yeah you are correct on the last part. But its why I enjoy it. I've never had too much experience on these but I'm surely getting some on this one.
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Thing is...no matter how much experience one might have with other forms of small engines these outboards are an animal all their own. Its easy to join a forum like this and be great at other mechanical things, thinking ya got this outboard thing down right away. Naaa...it takes awhile.
 
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