Logo
FULL SITE MENU

1999 Johnson 225 Ocean pro runs fine until motor comes up to temp then begins to misfire

D

dbrick1981

New member
[FONT=&quot][FONT=&quot]So I have a 1999 johnson 225 Ocean pro that I recently bought. I knew the boat sat for a few years so expected some possible issues. Ran the boat for the first time it wouldn’t miss here and there at low speed and missed pretty good at high-speed‘s. Took it back to the person I bought it from they changed the stator out and said they check the rectifier regulator and that was OK. Took it out for another test run with almost the same results, motor would idol fine but would miss fire more the higher the RPM and the warmer the engine got the worst the misfire, sounded almost like the motor was hitting a rev limiter, eventually it would just shake violently above 2000 RPMs. Took it home started testing some electronics, found I had a bad coil pack, changed out all the coil packs, spark plugs and wires. Tested again, ran good till motor warmed up, about 5 min then wouldn’t go above 2000 -2500 rpms it’s again like hitting a rev limiter, would just shake violently, but below 2000 rpm ok. Check motor temp when running, found it was slightly over heating , head were about 170 deg, replaced water pump and thermostats, now it run 146 deg alllll day long. Tested aging with same resoluts, run fine till up to temp then wouldn’t go over 2000-2500 rpm. Any help from here would be great!!! Thinking next to change out power pack??? Maybe something wrong with temp. switch??[/FONT][/FONT]
 
there's an overheat safety on the engine, so if it gets too hot, it goes into a sort of "shut down" mode, it sounds like its stuck in that mode. A lot of other people here know more than me, but its tough to keep replacing parts without knowing its the cause of the problem. You should be able to test the resistance of the power pack to know if its bad or not.
 
Try to obtain a measurement of head temperature near where the thermostats are installed on both the port and starboard sides while the engine is running and has reached operating temperature. A pyrometer would be ideal for this. I would be suspicious that you have thermostats which are delayed in opening or not opening at all. Do you have a smart gauge with this engine and if so is it alarming at all when operating temperature is reached?
 
Last edited:
An infrared heat gun can be used to measure temps on the heads, 20$ harbor freight, Can you hold a few fingers on the heads for a 7 second count, you should be able to keep hand in telltale stream all day.
 
Sorry so slow to get back, but changed out the power pack and all appears to be functioning good. Took two rides on boat with no issue! ��
 
Back
Top