15hp Nissan 4 stroke misses between idle and WOT

[LSB]

I have an '01 15hp 4 stroke Nissan that idles fine but it misses when I start getting under load. Once I make it to WOT, it starts to improve and eventually runs fine at high RPM/ It starts missing again as I drop RPM to slow. I have replaced the carb with a new OEM carb. I replaced the fuel filter and fuel line fitting on the tank side (o-ring was worn). I am running fresh marine grade fuel from a clean tank. I have replaced the sparks. Any ideas?

 

[dtj]

Re: 15hp Nissan 4 stroke misses between idle and WOT

I have an '01 15hp 4 stroke Nissan that idles fine but it misses when I start getting under load. Once I make it to WOT, it starts to improve and eventually runs fine at high RPM/ It starts missing again as I drop RPM to slow. I have replaced the carb with a new OEM carb. I replaced the fuel filter and fuel line fitting on the tank side (o-ring was worn). I am running fresh marine grade fuel from a clean tank. I have replaced the sparks. Any ideas?

Checked valve lifter gaps and magneto gap?............Don

 

[Sea Rider]

Re: 15hp Nissan 4 stroke misses between idle and WOT

Just in case, you should change both fuel connector external o'rings, as any of them could be sucking unwanted air, If it's a 2001 engine probably you are experiencing a hub slip, check prop.

Happy Boating

 

[pvanv]

Re: 15hp Nissan 4 stroke misses between idle and WOT

If you are confident in the fuel delivery, whip out your trusty Factory service manual and run through the ignition tests. Also check the auto-by-starter solenoid; if it's stuck in "rich" you might see that symptom. If so, you would likely be getting black plugs as well. There is no gap adjustment to the magneto. If the lifters were loose, it just would be a little low on power, so that's not a likely cause.

 

[TOHATSU GURU]

Re: 15hp Nissan 4 stroke misses between idle and WOT

Or continue to randomly replace parts.