SOLVED 1991 Johnson 25 HP Firing On Both Cylinders?

[Borgey401]

I have a 1991 Johnson 25 HP model # J25ELEID. I am pretty sure I should be getting more power out of this motor then I am as of right now. It's on a 15 foot West Wind Aerodyne and I am only getting about 20 MPH out of her if I'm lucky. I'm having the carb cleaned out and rebuilt tomorrow but I wanted to check it she was firing on both cyclinders before I did that. So I just went outside and started her up. I pulled the wire off the spark plug on the top cylinder and she still ran. Obviously she didn't run all that great with it off but it did not stall. Then I put the top wire back on the plug and took off the bottom wire. She then started to putter more then the when the top was off and after about 30 seconds or so stalled out. It would without a doubt run when only the top spark plug wire was plugged in but did not seem to perform as good as the other cylinder. Is this something I should be worried about? Any suggestions as what to do next (if anything)? Like I said I am getting the Carb cleaned tomrrow (was also thinking maybe the high speed jet was clogged up). I basically just want to have a healthy motor like everybody else would want! Thanks for the help in advance everybody! This forum is absolutely AWESOME!

 

[DJ]

Re: 1991 Johnson 25 HP Firing On Both Cylinders?

Re: 1991 Johnson 25 HP Firing On Both Cylinders?

Your botom cylinder may be a little down on power. Check compression.

Boat speed is not a good indicator of engine health or set up. RPM is.

 

[dradford78]

Re: 1991 Johnson 25 HP Firing On Both Cylinders?

Re: 1991 Johnson 25 HP Firing On Both Cylinders?

Im new to this but you could get a spark plug wire tester to see how the spark is coming from that wire. Also with an electrical tester you could test the resistance in the plug wire.

 

[Beek14]

Re: 1991 Johnson 25 HP Firing On Both Cylinders?

Re: 1991 Johnson 25 HP Firing On Both Cylinders?

DJ may be right, sounds like the possibility of lower power in the bottom cylinder than in the top. If there is a decent difference in compression between the two cylinders, that may be exactly what your problem is. Put the compression tester to it before you do anything else.

 

[Borgey401]

Re: 1991 Johnson 25 HP Firing On Both Cylinders?

Re: 1991 Johnson 25 HP Firing On Both Cylinders?

I have checked compression before and all was well on both cylinders. I forget exact readings but I will test it again tomorrow and post results. What else could it be if not compression?

 

[Borgey401]

Re: 1991 Johnson 25 HP Firing On Both Cylinders?

Re: 1991 Johnson 25 HP Firing On Both Cylinders?

Im new to this but you could get a spark plug wire tester to see how the spark is coming from that wire. Also with an electrical tester you could test the resistance in the plug wire.

Good thinking, I should probably test that for sure. I just don't have the tools to do a spark test. I am sure I can pick one up tho soon. I am supposed to get my carb cleaned tomorrow and I think that'll help the overall performance of my motor. It sat for a good year and a half. It runs great fine from what I can tell but I just thought I should be getting more power out of it at WOT. I guess I could also be wrong and I'm just used to bigger more powerful motors also.

 

[dradford78]

Re: 1991 Johnson 25 HP Firing On Both Cylinders?

Re: 1991 Johnson 25 HP Firing On Both Cylinders?

My johnson 9.5 was having trouble getting going. I would open it all the way up and it wouldn't even make a wake. Figured out that when I throttled it up it wasn't actually making the carb open up. One screw tightened down and it fixed that problem. Check and see if your throttle on the carb is moving when you throttle up.

 

[Borgey401]

Re: 1991 Johnson 25 HP Firing On Both Cylinders?

Re: 1991 Johnson 25 HP Firing On Both Cylinders?

Well I figured out what was wrong when me and my buddy were removing the carb. There are two bolts that are connected to the throttle to advance the timing when giving it gas. Well one of the bolts were missing and the timing was completely off. I rebuilt the carb and got another bolt on there. Took her out for a couple hours and she is running like I wouldn't even have ever imagined. I am very satisfied with this little motor I must admit! ( SORRY FOR THE LACK OF OUTBOARD MOTOR TERMS AS I AM NEW TO OUTBOARDS)