Danielc1234

I have two 2005 Honda F-12x jetskies. One of them seems to be running on three cylinders during low RPMs, but once you hit around 5,000 RPM it runs great. I have replaced the Computer brain and spark plugs.
One note...when I took out the spark plugs to be replaced, the #4 plug was more black with carbon than the rest of the plugs. So I thought I was just having a fouled plug, but after changing the plugs, it ran a little better, but still experiences that rough idle, etc. And another thing is, it seems to happen with a load on the engine. It wont do it out of the water with no load.

Is there anything else I can look at to resolve this problem?
Thanks in advance...Daniel

jrinjax

Leave it tied to the trailer with the seat off and see if all the cylinders are firing by unplugging the coils, one at a time while holding the throttle at 3-4K RPM. This is a good time to do it since there is no one at the boat ramps right now. If you find dead cylinders, do a compression test on them.