Johnson 225 WOT problem

[jim_b_20653]

I am having an intermittant problem with my 1990 225 Johnson. It starts and idles fine, but when running at high speed it sometimes falls off plane and starts to "buck". This happens at different frequencies, sometimes I can go for 60 mins with no problem, sometimes only 5-10 minutes. When this occurs the engine continues to run and will run fine up to about 3000 RPM then it seems like the ignition is turning off and on. I have found that if I turn off the ignition and restart it fixes the problem.

My question is does this engine have some sort of safety feature that limits the RPM's? Has anyone else experienced this problem?

This engine does still use oil injection, and I recently upgraded to a new 4 wire VRO pump.

 

[Dhadley]

Re: Johnson 225 WOT problem

Sounds like it's going into S.L.O.W. (speed limit overheat warning). The hot horn should be going off too unless it's picking up a false reading that sends it into SLOW. Does the horn self test when you turn the key on?

 

[jim_b_20653]

Re: Johnson 225 WOT problem

Yes the horn sounds when Ignition is first turned on. I also tested the alarm per the instructions when I replaced the VRO pump. The indicated temp is ok when this happens, and I have good flow out the telltale.
Does this SLOW system limit RPM's to 3000?

 

[Dhadley]

Re: Johnson 225 WOT problem

Yes, the rpm will be limited until you shut it off and restart. If you can verify the motor is indeed not overheating then something is sending a false or premature signal. Hopefully it'll simply be that side of the temp sender.

 

[jim_b_20653]

Re: Johnson 225 WOT problem

I dont think is is overheating, I have plenty of flow out my telltale, and when I put my hand on the block it is warm but does not burn me. I am ordering a cylinder head temp gage. The previous owner connected a faria temp gage to the same sending unit as the hot horn by soldering it. I think I should probably replace the original sending unit. I believe that it just screws into the water jacket on the head.