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1991 25HP Johnson Tracker Outboard - Carb or Possibly sheered fly wheel key? Torque Specs?

A

akarbarz

Member
Hi everyone,

I have a 25hp johnson (TJ25ELEID) and its been running fine up until a couple weeks ago. The motor while cruising along started sputtering and died almost like it was out of gas, fuel was low but enough that it shouldve kept running. I managed to start it up a few times after but always had to give it a lot of throttle in order for it to start. If I brought throttle too low, it would die. I thought perhaps it was the carb and it just sucked something outta the fuel can when it was low. I pulled the carb off and took it apart and let it soak in berryman chem dip parts cleaner for a little over a day, took it out blew it out with an air compressor and put it back in the cleaner for another night (not my first rodeo lol) and blew it out again the next day. Then I rebuilt the carb and put it back on the motor. Motor wouldnt start at all now. Figured I didnt adjust the float properly, took it off and readjusted to allow more fuel in, still no start.

At this point I am starting to think I may have sheered the fly wheel key. I replaced it about a year ago when I had the fly wheel off and I never lapped it like I am now seeing is reccommended and am thinking something wonkey could be going on there. Thoughts? And does anyone happen to know the proper torque specs for that fly wheel nut on this engine?

Thanks!
 
My starter has been a bit loose since I didnt have the proper locking nut so I'm going to pick that up and then I'll check compression and post results.
 
125PSI top cylinder 115 bottom. Out of no where after all that cranking a bunch of has started leaking down the side of my outboard and it looks like it was coming from the main fuel hose to the carb bowl. Going to replace the line and tighten with a zip tie within next couple days and see if that does it.
 
That is a good point. I feel like even if there was a leak it would at least try to start but not sure what else it could be. I did forget to double check the spark, I'll check that out too soon and report back.


The more I think about it though I would be very surprised if it didnt have good spark. As I mentioned the motor ran fine then started sputtering and died. Before I pulled the carb off I could continually get it started if I opened up the throttle (would die if I returned it to idle). Only after cleaning the carb have I ran into a no start situation.
 
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Well I checked it out and spark is good, strong and blue. Means spark + compression are there. Going to triple check carb and fuel lines tomorrow. In the mean time I dont think i need to pull flywheel off.

I took an image of the timing marks at the top cylinder approaches TDC so not quite BTDC because I dont have the tools or know how to check BTDC perfectly:


BTDC_ish.jpg

The manual says that the timing mark should be at 30+-1 BTDC. Im guessing if the woodruff key was sheered this photo would be much further off. If anyone has any other ideas on things I should check out let me know. Thanks!
 

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If the flywheel key is haunting you pull flywheel off and double check it.30 degrees Timing is at full throttle under load.Did you check your linkage adjustments for throttle plate timing?
 
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Haha, it is but im putting it off because i dont currently have a puller, a torque wrench, or a strap to hold the fly wheel in place but with how often I feel like I work on this stuff might be a worth while investment.

If you mean throttle plate timing as in ensuring that the throttle plate just starts to open as the cam roller gets between the two little marks then yes. Otherwise if its something different then no I have not.
 
Huh. Well I also took a pic of the timing marks with #1 piston at TDC:
TDC.jpg

If I count the teeth on the fly wheel back from the markings that sure looks like 0 degrees in my limited know how.

Since that pointer is basically showing 0 degrees with piston #1 at TDC that means the woodruff key should be fine right?
 
Dont have another tank and hose at the moment. My fuel tank is a pretty old plastic one that came with the motor years ago so it might be worth replacing. Did not touch the fuel pump either. My thought process was that the motor would at least start even if fuel pump was bad because I know the carb bowl is getting filled with gas when I prime the bulb. Not sure if thats accurate thinking though.
 
Well I went and checked it out and couldnt find anything out of the ordinary. Might order a new one tonight anyway just because I dont trust the cleanliness of my current one. HOWEVER, i did find something highly suspect and I believe may be the culprit!! Please verify if you can or let me know what you think!

I took the carb off again and looked into the intake manifold and the leaf plates? reed valves? not quite sure what they are called but one of them is missing, I dont think that is normal. Right???

Attaching some images, if you look inside you can see 1 of those little plates are not there covering that opening. Here is the part im refering to that looks like something is missing: https://www.marineengine.com/newparts/part_details.php?pnum=OMC0437712&pass_title=0437712+:
IMG_3278.jpgIMG_3279.jpgIMG_3280.jpg
 
Not good for sure.Guess you will be digging deeper.I see all the paint is off the nuts holding the intake on.Wonder if it was off before?
 
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Yeah its been off to replace gaskets. Just pulled off the intake now and the leaf plate definitely broke off. Worst part is I cant find it right there. Im assuming this means I need to pull the power head off and take the entire thing apart and look for it and pray it didnt reach the cylinders? I just checked compression yesterday and it was good.
 
The broken pedal went out bottom cylinder , thats the reason for low compression reading. Need to check RPM as excessive will break reeds and pull head and check cylinder damage
 
Sounds good. Ill pull the bypass cover off and inspect the rings and will also borescope the inside of the cylinders to see if theres any damage and determine if I need to pull the head. From what I remember my compression readings last time I checked, a year or so ago, were very similar. I might just be trying to convince myself that it got chewed up and spit out through the exauhst with minimal damage but I dont think im that lucky. Wish I woulda caught this sooner, I ran the motor quite a few times around the lake and have cranked it a bunch too since trying to diagnose the issue. So I'm going to assume whatever damage would have been done has likely been done at this point
 
Sorry to wake an "older" thread but figured id give an update incase someone comes across this in the future. After removing the bypass cover I did not see any damage to the rings and still could not find any evidence of the leaf plate. I decided to go for it and replace the leaf plates and it started running great again. I have since put quite a bit of hours on the motor and no further issues have been found. Thanks again to everyone for the help.
 
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