Honda 225 spark plugs not firing

[fountainboater]

I have a 2003 Honda 225 on a 27 foot Premier Pontoon. The motor only had 38 hours when I got it and now has 89 hours. I had an issue where it would not run on all cylinders and was running really rich and fouling spark plugs. I ended up taking it to a dealer and the 02 sensor was replaced. Even after the sensor was replaced, it would start and run on 4 cylinders until it warmed up. Then the other two cylinders would kick in one at a time and it would run great 6000 RPM at WOT. I had my wife pick me up a replacement spark plug and she got a standard type plug instead of the iridium I went ahead and installed it and the bad cylinder started firing. However when I bought the correct iridium plug and put it in the cylinder stopped firing again. it only fires with the standard plug. I had not run it in a few months and when I put it in the lake this weekend I could never get it to run over 4000 RPM, so I think there are two cylinders that are not firing. Could this be bad or weak coils? The motor is not showing any error codes. Please help.

 

[TOHATSU GURU]

Re: Honda 225 spark plugs not firing

It needs to be taken into a Honda dealer and they need to run the diagnostic software on it.

 

[Primalurges]

Re: Honda 225 spark plugs not firing

I had a similar issue however it was just one plug that wouldnt fire and it turned out to be a bad computer. Try unplugging when coil at a time and check voltage with multimeter. If you find one or more with no power you either have a bad harness or bad computer.