2003 30hp Johnson Enforcer 2-stroke outboard missfire?

[MMcCawley]

Hello,

I recently purchased a jon boat from someone with the a 30hp 2-stroke Johnson which was said to be in good running condition although it had sat for roughly 9 months. After not being able to get it to run, I replaced the plugs and cleaned out the carb and it fired first pull although it wouldn't run very smooth and at times remains difficult to start. I've taken a short video of the outboard running as it appears to missfire. Am I diagnosing it correctly or is something else going on? Any insight you can provide would be greatly appreciated.

Model #: J30MLSTSView attachment Johnson 30hp Outboard Video.mov

Thanks!

 

[racerone]

To me it sounds like the classic ----lean sneeze-----Caused by low speed needle in too far.---Or throttle plate opening too early.-----Easy fix in my opinion.

 

[saltchuckmatt]

Yes, or junk in the carb/idle circuit.

Best to send us compression test numbers and then go from there.

 

[saltchuckmatt]

Here's a 2000 I just finished servicing
.

Your motor should run like this.

 

[MMcCawley]

Thank you both for your replies. Both cylinders are at 135 psi.

I'll search around to see if I can find the low speed idle setting and adjust accordingly. I've had the carb apart twice and haven't seen any junk in it. I also cleaned out the fuel filter but it was pretty clean to begin with.

 

[MMcCawley]

Quick update- I adjusted the low speed needle and the "cough" seemed to go away. The motor was running a lot better but still not great in my opinion. I ended up taking it for a quick sea trial and the motor wants to stall under load. No problem revving in neutral, only under load. I'm going to rebuld the carb and replace the squeeze ball line. A little frustrating but hopefully I can get to the bottom of things. To make matters worse, the "leak free" jon boat has three pin holes in it. Oh well...

Any other areas to look into on the outboard are appreciated. Thanks

 

[saltchuckmatt]

Carbs come off fast....try just cleaning it.

I use torch head tip cleaners to team out the orifices. Easy.

Hot trick, instead of removing the starter and it's brackets, hit the port side carb nut with a small cold chisel or screw driver to remove it.

Save's tons of time and you might not need to do a link and sync.

Put it back on the same way.

Procedure is, pull off carb linkage (pop),
Remove upper primer hose (careful of small nipple), remove the two half inch nuts, pull off carb slightly....turn over...cut my tie and pull off fuel hose.

Take to a clean environment and clean.

 

[racerone]

Thermostat in place ?----A " new to you" motor should have a new water pump impeller installed.