1996 Johnson 25 HP long shaft J25RLEDA, sounds like its sucking air and dying

[jitterbug127]

I recently purchased a 1996 Johnson 25 HP motor for my boat. The carb was rebuilt by my buddy right before I bought it. I took it down to the river about a week ago. Motor had a little bit of a hard time starting but once I got it warmed up she ran great. We went up and down the river several times for a good couple hours.

I took my boat out yesterday to fish, and I couldn't get it to stay running. It sounded like it was sucking air and then would die. I even tried to throttle up a few times to see if that helped and no luck. Motors has great spark and good compression.

The only thing I've done to the motor are swap out the NGK plugs for the recommended ql77jc4 plugs. I put a K and N inline filter on my hose/tank since I'd been to the river last. This tank/hose has been used for several barrel tests on multiple motors since it has been installed. I feel confident to say the inline filter/tank/hose all work. I took the cap off my tank to allow more air to pass through incase it might be that.

I did get new fuel right before going to the boat ramp yesterday, and I properly mixed that with the same oil I always have used.

I am going to try fresh gas, and I could try putting the NGK plugs back in to see what happens. Any other suggestions to see what I could do? I believe this to be a fuel issue and not a spark or compression issue. My bulb held firm the whole time. No fuel leaks.

 

[jitterbug127]

Motor is a rope start. Long shaft. Pumps water really well.

I do have the low speed idle screw turned out quite a bit more than standard (3 turns if i remember correctly), but that was how it was needed to idle properly last time on the river.

 

[airshot]

How much gap will spark jump ? Great compression means nothing, actual numbers are needed. Were carbs just cleaned or an actual rebuild with factory rebuild kit??

 

[jitterbug127]

How much gap will spark jump ? Great compression means nothing, actual numbers are needed. Were carbs just cleaned or an actual rebuild with factory rebuild kit??

I try to give as much information as possible and always forget something

Spark Jumps a 3/8-7/16" gap. Nice blue spark. Carb kit was rebuilt with OEM kit. Compression I checked like 110/110 when I bought motor. Can check again for good measure.

 

[jitterbug127]

Double checked when I got home tonight

125/120 compression
Spark jumps 3/8” gap without fail.

 

[jitterbug127]

Motor passed the paper test on the carb. I was wondering if it might be the reed valves. More trouble shooting to do

 

[jitterbug127]

I got down to the river today. Got the motor to start. It’s still bogging down and running rough. I can’t seem to get it ti idle. The pawls on my recoil broke, so I’ve got some repairs ti be done before I can continue troubleshooting.

 

[saltchuckmatt]

I got down to the river today. Got the motor to start. It’s still bogging down and running rough. I can’t seem to get it ti idle. The pawls on my recoil broke, so I’ve got some repairs ti be done before I can continue troubleshooting.

You must have one of those "saltwater models"

 

[jitterbug127]

You must have one of those "saltwater models"

If I've got a salt water model in Indy we've got some major problems.

the good news is my little 6 hp Johnson is running incredibly well!

I am going to take this motor to a guy up the road to have him look at it. I could start replacing Reed valves, upper/lower crank seals, intake/bypass covers etc. I have no clue what I'm doing on this one, so gonna seek some alternative help.

My plan of action:
1. Rebuilt carb again...buddy of mine that does GOOD work did it, but sometimes things happen.
2. I've got a second carb I'll throw on there if that does work.
3. Take it up the road. Guy said to test the timing or i might have some sort of vacuum leak.

 

[jitterbug127]

Ill try to get a video of this thing going after is get those Pawls replaced

 

[jitterbug127]

Solved this one Thursday. Motor was having fuel pump failure symptom that I can hand pump bulb and keep it going. I put 3 fuel pumps on same thing. The little third hose was slightly kinked just enough to keep motor from running well. Replaced that fuel line and she runs great. I had it out on the water for several hours Friday. This motor is a beast. I'm thrilled.