Intermittent Misfiring 225

[boatingnyc]

I have a 1998 225 (carbureted) that has been misfiring underload or above 4000 rpms. Last night, after searching for posts about this issue, I used a timing light on each cylinder to see if I had a bad CDM module. No luck, evertime the engine misfired, the spark stopped on each cylinder for about a second. No one CDM seemed to act differently when the engine misfired. The engine has low hours, around 200, and very clean, no corrosion on any of the electrical connections which I double checked. I also inspected all the wires on the engine for any wear which may cause it to short out. The annoying problem is that is slowly getting worse. About 3 weeks ago it might misfire once the whole day. Now it will almost always misfire above 4k rmps or lower rpms if a lot of people are on the boat. Before droping it off at the dreaded mechanic any suggestions?

 

[Drybo]

Re: Intermittent Misfiring 225

Sounds electrical but trouble shoot the easy things first,<br />Fuel bulb- Gets hard? I had almost unnoticable air leaks in mine, squeeze it at idle, rpm change?<br />if so get a oem bulb.<br /><br />Fuel pump, filters good/not blocked?<br /><br />Hopefully someone with your type motor/ and more info will respond.