1998 Johnson Ficht Fast Strike Stumbling, missing at 1300-2000 rpms?

Motor starts and idles fine,(yes it still runs.. http://www.bassboatcentral.com/smileys/smile.gif believe it or not ) and is fine at rpms above 2000, but seems to have this small annoying miss/stumble at 1300 to 2000 rpms when engine is cold or warm, any ideas please? Changed plugs (indexed them), ohmed spark plug wires, and power packs, no engine trouble lights on, new starting battery (delco voyager), dont know what else it could be? Thanks for you help!!

What plugs are you using.?Did they all look about the same when you pulled them out?

They were XC12PEPB, gapped at .30, Champion Plugs, I have the pinned cylinder heads. All the plugs looked the same when I took them out to inspect them.

Is the stumble something that just started? We have a map changeover in this range, it was always somewhat noticeable. Also, have you changed out the spark plug wires?

I have owned the boat and motor for about a year and it has been there since I owned it, sometimes its not as bad, but it is definatly there, and I have ohmed the spark plug wires to check resistance, and they came back with in specs. (dont know if a bad one can check out ok??) so should I try changing them? Thanks!

If you look closely at them and see any carbon tracking,little grey spots on the wires where the pass next to metal, yes. At this point in the map, we change from stratified to homogenous in the ignition system, any spark that get out is wasted and throws off the burn. You may always have a little hiccup here. If the wires are original or appear to be, replace them.

Will check those wires and see, Thanks alot for your help!

All in a days/nights work. Good luck! http://xs-s.com/zf/images/smile/emthup.gif

By the way what do these spark plug wire sets usually run?

They are bought individually, about $12.00 a peice, may be more on the older motors. http://www.bassboatcentral.com/smileys/ohwell.gif

I just replaced the wires on my 175 97 Fastrike. Had a couple of them touching the bare head bolts, could see where they were sparking. It was missing at random speeds. Just my two cents.....