2003 115hp Johnson 2 stroke intermittent bogging

[Maryland Sport Fishing]

Need help with this problem.

2003 115hp Johnson 2 Stroke...ran it about 40 minutes, then at 4,500 rpm seemed like there was an intermittent miss. Then continued then the intermittent miss was more pronounced and the engine bogged, loss power, and rpms dropped to 2,600 - 3,200. Dropped throttle to below 2,000 and motor ran fine. Stayed at 2,000 rpms for a minute and then throttled up to 4,000 and motor ran fine for 2 minutes then started to repeat the symptoms, so throttled back down again. After a couple more minutes at lower rpm I throttled back up to 4,500 and it ran fine for about 15 minutes, then the symptoms returned.

Any ideas on what this could be?

Thanks!

[Maryland Sport Fishing]

No alarms

Just wanted to mention that there were never any alarms going off when the symptoms were occurring.

Could this be as simple as a bad spark plug? Or does it seem more like a power pack? Doesn't seem like a fuel issue, but I am not sure.

Any help would be great!

[Solarman]

Is this fuel injected, or carbs?
Sound electrical to me, might be plug wire(s), plug(s), coil pack, starting to break down at higher RPMs? but I don't know much about your motor. If fuel injected, it could be fuel pressure too?

Good luck.

[Maryland Sport Fishing]

Follow up

It is carb.

Trying to go the cheaper route first, I replaced the plug, fuel filter, water separator, fuel bulb, and the fuel line from the fuel bulb to the motor.

I will give it a shot this weekend and see if the problem comes back.

[jvd61182]

My 96 48hp SPL is doing the same thing. I've replaced the carbs, lines,fittings, tanks, fuel pump and plugs and it still does it. Looking electrical now. It idles rough and rich as well. If you figure out what it is please post back I'm tearing my hair out with and going broke. Electrically I've checked the temp sensor that was good but the blocking diode test said its bad but I don't know if I did it right. If I figure it out I will post back as well. Thanks.

[Solarman]

If you have a timing light, it might be your trigger coil/ timing coil acting up. Could use a timing light for simple test, check timing/fire for each cylinder at TDC. Mark tdc (top dead center) for each cylinder on flywheel ( 1,2,3, etc) add water, start, and test timing for each cylinder. If good it will fire at tdc for each cylinder smoothly in same place for that cylinder.
If bad (peak voltage test next check - to verify it's bad), one or more cylinders may fire at different locations (bounce around) flywheel, instead of where tdc should be at for that cylinder.

Good luck. Post back if find anything.

[Maryland Sport Fishing]

Still having same issues...

Finally had a chance to go out again after replacing the fuel filter, fuel bulb, and plugs. At about 5,000 rpms I noticed that the rpms started to decrease slowly, then at about 4,200 the motor seemed to miss and shake as the rpms dropped more. Even running at 3,000 the motor would shake some and lose rpms. Then later I was able to run at 5,000 - 5,500 rpms without any of the earlier issues. My next try is to replace the antisyphon valve on the fuel tank...I need to see how my access is first.

[Maryland Sport Fishing]

Problem continuing

Still think this is some sort of fuel issue.