78 johnson 25 stalling issue, Pics added plz look

[mmawonder]

Well, motor runs usually fine. Start up procedure is full choke and about 4 pulls cold. It wants to stay choked until it warms up, if I put the choke back in within the first 4-5 minutes it dies. I am not sure if this is normal. Anyhow, after it warms up, it runs well on idle in neutral, however as soon as I put it in gear, it wants to stall on me, if I give it a little gas, it picks right up and runs great, if I back off the throttle completly, it starts to studder and stall. I was thinking that I could solve the problem by rasing the idle, however if there is another way to fix it let me know, since if I raise the idle, I would be putting it in gear at a high rpm which cant be good for the tranny.

 

[Mas]

Re: 78 johnson 25 stalling issue

Re: 78 johnson 25 stalling issue

I'm betting your carbs are gunked up. Raising the idle is not the solution, unless it somehow rattled loose....which is unlikely. Pump the fuel line bulb...see if this helps.

You need to also check for a strong blue spark & do a compression check if you haven't already.

But again, I'm betting on a gunked up carb. When was the last time the carb was gone through? Probably you've got some varnish in the jets ot idle passages.

MAS

 

[mmawonder]

Re: 78 johnson 25 stalling issue

Re: 78 johnson 25 stalling issue

I'm betting your carbs are gunked up. Raising the idle is not the solution, unless it somehow rattled loose....which is unlikely. Pump the fuel line bulb...see if this helps.

You need to also check for a strong blue spark & do a compression check if you haven't already.

But again, I'm betting on a gunked up carb. When was the last time the carb was gone through? Probably you've got some varnish in the jets ot idle passages.

MAS

I have no idea when it was last cleaned, I just got it a week ago. I am not sure how to do a compression check, I could check the spark though since it starts easy and runs well and strong after I dont think its any of those. It maybe the carb...

I discovered another thing today, the motor at low rpm would run fine for 10-15 seconds than all the sudden for a 1 tenth of a second the motor would stall and come right back up, but it happens very very fast, it fels like it passed a small drop of water in the gas or something. I had my vent open during the rains, maybe it did take a little water or something...

 

[tashasdaddy]

Re: 78 johnson 25 stalling issue

Re: 78 johnson 25 stalling issue

First read this: http://forums.iboats.com/showthread.php?t=158086

you need to clean the carb, and install a rebuild kit, then adjust.
http://forums.iboats.com/showthread.php?t=244013

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

 

[Mas]

Re: 78 johnson 25 stalling issue

Re: 78 johnson 25 stalling issue

If you're planning on working on the motor, first buy an OEM factory manual...not chilton or seloc or other brand. The OEM repair manual will detail and illustrate every step of every repair. The other manuals just try to cover too many models and as a result, do not do a quality job of either.

kencook.com bought the rights to all the older service manuals and you can get one there, but you might find a used one cheaper on eBay.

Reading the manual will give you a strong base to start any repair or maintenance job, which can then be peppered with questions on this forum. Rebuilding the carb is not a difficult job.

Compression checks are easy if you have the gauge. ($25-35 at an auto parts store): Unscrew both plugs, screw in the gauge, ground the ignition so the plugs do not fire and fry your ignition, crank the motor about 5 or so revolutions and the gauge will read the pressure in psi. This step will tell a lot about the health of your motor.

Since the motor is new to you, you need to replace the water pump impeller as well!

MAS

 

[mmawonder]

Re: 78 johnson 25 stalling issue

Re: 78 johnson 25 stalling issue

Water impeller sems to be doing ok since there is a steady stream of water beeing pissed out of the motor. I guess removing, cleaning, rebuilding and adjusting the carbs is the first thing i am going to do.

 

[mmawonder]

Re: 78 johnson 25 stalling issue

Re: 78 johnson 25 stalling issue

Well now I have a bigger problem. I took out the carb and let it soak in carb cleaner for 3-4 hours, after that with a wire strain I tried to clean out the jets, put the carb back together, then pulled the spark plugs, they were a little oily, looked like it was runnig rich, brushed them clean and re installed them, puleld the slow speed adjuster 1 1/4 turns out as it says on the black box as a starting point. Flushed the gas tank with some gas, drained it, put fresh gas and oil 50/1. Flushed the gas line of the tank and fuel line of the carb. Squeezed some gas in to the carb un til the bulb was hard, pulled the choke and gave it some pulls, on the third one it started and ran for about 40 seconds than it died. I tried to restart it and played with the slow speed adjuster for about 20 minutes , I couldent start it. Then I realzied that the vent on the tank was closed to I opened that and tried for another 10 minutes using different combinations on the slow speed needle and choke configurations and I cant start it. I got sweaty and tired from trying to pull start a 25 by hand for 30 minutes, so any help would be appreciated. I hope I dont have to pull that carb out again...

 

[mmawonder]

Re: 78 johnson 25 stalling issue

Re: 78 johnson 25 stalling issue

update, I just pulled the spark plugs again and there is gas on them, so I dont think fuel is the issue, its either the spark or carb adjustment, or it may be floodded.

 

[jbjennings]

Re: 78 johnson 25 stalling issue

Re: 78 johnson 25 stalling issue

Sounds like it got flooded to me. I suspect your needle and seat is not spotlessly clean and it's sticking on you. The first time it died was when it ran out of fuel in the float bowl, then, after all the adjusting and pulling with the adjustment wrong, the float needle dropped allowing fuel in and it loaded up the cylinders with fuel and killed your spark. Dry off your plugs, clean the needle and seat, bus sure to replace your fuel lines, and give it another shot. A johnson motor in decent shape that's properly tuned will usually crank by the second pull from my experience.

 

[mmawonder]

Re: 78 johnson 25 stalling issue

Re: 78 johnson 25 stalling issue

I removed the needle and the seat and found out that the rubber piece at the end of the needle is half gone, it looks like it either cant seal right, or the ripped of piece of ruber is blocking the path. Anyhow, just bought me a carb rebuild kit and putting it together, will post here if it makes a difference..

Ps: I think you were right about the floodding, the spark plugs were really wet when I pulled them off.

 

[mmawonder]

Re: 78 johnson 25 stalling issue

Re: 78 johnson 25 stalling issue

Well I bought the carb rebuilt kit and rebuilt the carb. Here is a pic of what has been replaced.



This stuff was left over from the kit, I am not sure what they were supposed to replace but couldent find it.




During installation, one thing caught my atention, that the needle would stick for a very brief moment to the jet, if pressed hard enough with the float. When float relased, the needle would take a very brief moment, before falling in its place. I recognized this while adjusting the float set. I moved the needle around and it seemed moving freely so I installed the rest of the carb back on the motor.

I primed the bulb, choked the motor and after second pull the motor started. After a brief warm up perior I pushed the choke back in and motor ran fine. Then I started adjusting the slow speed needle and broguht it to a point where it would idle and run, with the throttle completly closed. "which was the main reason why I took this carb cleaning project in the first place" Now everything is good, I started putting around the marina slowly, on idle speed for about 10 minutes or so. by now the motor has been runnig for 20-25 minutes staright. Impeller/water pump working good, motor not smoking much getting good fresh pre-mix. Right at that momet I tried to speed up and I opend the throttle a bit, raising the rpms by about 1000, drove the boat about 40 seconds and right then rpms dropped to idle for a second, came right back up to where it was and then it died. I was in the middle of the channel and tried to start it again. What would happen is, it would start but only run for one second, before dieing again. Motor stopping is not like stalling, its more like the kill swithc beeing pressed on. I cant figure out why it did that, but I got towed back. After I got towed back, about 5 minutes later, I pulled on the cord again and it started and ran fine again.

Thats the story, can you guys come up with a possible problem?

 

[jbjennings]

Re: 78 johnson 25 stalling issue, Pics added plz look

I'm wondering if possibly you have some wire chaffing in a location where the wires might possibly rub when you give it the throttle and it turns the armature plate, causing a short and killing your spark. I'd also look for cracks or nicks in the spark plug wires which may be shorting out when you turn the armature plate they're attached to when turning the throttle.
Hard to say. You may try running it with the cover off at night in a barrel and looking for arcing which would show you where your ground problem may be.
Sorry, I know how frustrating this kind of stuff is. If it's any consolation, this stuff can happen to a professional mechanic, too, I would think!

Since it cranks and only runs for a second or so, I'd think it may also be something restricting your fuel. I'm also thinking you may want to check that needle valve again. Pushing really hard on the needle may tear the neoprene tip and cause the exact same problem you had before.
You'll find it,
JBJ

 

[mmawonder]

Re: 78 johnson 25 stalling issue, Pics added plz look

Tnx for the reply, i just went outside and pulled the choke, pulled the cord and on the third one it started, I put the choke in about 20 seconds after and now its purring like a cat on neutral, idle withthrottle completly closed.
I am going to take the cover off now to see if I can see any arching, since its night time.

Ps: I pulled the cover off and ran the motor, I dont see any arching anywhere, I looked at the spark plug wires and ignition area. Maybe I should take the carb apart again.... man used outboards come with a ton of problems.... I know this is a good motor and it wants to run fine, its just something simple that I cant figure out.

 

[tashasdaddy]

Re: 78 johnson 25 stalling issue, Pics added plz look

it is very possible the coils are getting warm and failing. check the spark immediately after it shuts down. did you remove and clean the high speed jet? http://forums.iboats.com/showthread.php?t=244013

 

[mmawonder]

Re: 78 johnson 25 stalling issue, Pics added plz look

I removed the screw on the bowl but did not ran a wire strain thru the high speed jet. I will remove the carb and do that today. According to the pics, was there something else that I was supposed to replace with the carb rebuild kit?

How can I check the spark right after its shut down? Remove the spark plug, ground it on the motor somewhere and pull the cord to see what color its jumping?

Ps: I have read your carb cleaning list, do I need to remove the high speed jet to clean it? Since I dont want to get stranded in the middle of the channel, how can I re-create the situation where the coils would heat up? Would just letting it idle for like 30 minutes give the same result, should I rev it in neutral a little bit?

 

[jbjennings]

Re: 78 johnson 25 stalling issue, Pics added plz look

IF you go to autozone you can get a spark tester for about 6 bucks. Use it to test your spark.
I wonder if it could be your kill switch? IT woldn't be the first time one of them has caused this problem.
But I would definitely try TD's suggestion. I've had coils heat up and cause a similar problem, too. I wouldn't rev it in neutral, and suggest your don't---TD would suggest the same. Use the 6$ spark tester while out on the lake. OF course, don't go far from home.
Personally, unless you have the right tool, I wouldn't remove the high-speed jet. You can booger it up. If you have an air compressor I'd let the carb soak in carb cleaner for a few hours and use a tip to blow compressed air through the jet. It works most of the time. A small piece of piano wire or similar diameter copper wire works, too.
GOod luck,
JBJ​

 

[Rick.]

Re: 78 johnson 25 stalling issue, Pics added plz look

Just reading your post for the first time.Your getting good advice from the top of the class. On your second post ( and I do realize your way beyond that point now) that 1/10th of a second stall you mentioned is called sneezing and indicates too lean of a mix. You will read about it in the parts about setting your low speed needle valves. Thought you would like to know. Good luck. It's only a matter of time. Rick.

 

[mmawonder]

Re: 78 johnson 25 stalling issue, Pics added plz look

Ok well thanks to everyone who have contributed here, I am lucky to find these forums with many knowledgable people about outboards. My problem is solved. I took the carb apart the third time, to check evertything and realized that the new needle was stuck in closed position. I took it out and looked inside the jet to see a tiny rubber particle from the previous destroyed needle. Removed the particle, ran some carb cleaner thru it, removed the bowl drain screw, couldent get the high speed jet out and didit try hard, not to boggle as jb said, ran some carb cleaner there too, put it back together, and now it works fine.
Previous symptoms was, not idling right, not warming up for a long time and wanted to run with the choke for about 5-6 minutes at least on 70 degree weather, high speed hesitation and low speed stalling.
Current state is, idles fine, warms up quick and does not need choke in less than a minute, no high speed hesitation, starts in one or two pulls max and no stalling at low speeds.

I adjusted the low speed jet using tasha'sdads guide and I found out that 1 1/2 turns out "factory recommended" was too rich and about half turn out was too lean, so I set it around 3/4 turns out. It still shakes a little bit and does not run as smooth as a 4 stroke honda but it gets the job done. Any leaner and the shake goes, rpms increase but the motor stops after 5 seconds, so 3/4 is where it is going to stay.

 

[Rick.]

Re: 78 johnson 25 stalling issue, Pics added plz look

Fantastic news! In the future please refrain from using the " H " word in your posts. Great news really. Rick.

 

[mmawonder]

Re: 78 johnson 25 stalling issue, Pics added plz look

He he he ok ill try