1994 Johnson 150 HP

[z.fields27]

About 3 months ago I got a '94 Stratos with a Johnson 150 and the engine was running perfect. A few weeks ago however I went on a fishing trip and the motor had some issues. I was idling along when an alarm sounded. My first thought was to make sure it was still peeing (which it was) then I thought to make sure I hadn't run out of oil. When I stood up smoke was pouring from the vent on the cowling. As soon as I realized that I shut the engine off and took the cowling off. As bad as the engine was smoking I was sure something was on fire. I then used my fire extinguisher just to realize it was doing nothing. Soon I realized it was some kind of electrical part burning up. I disconnected the battery and slowly the smoking died off. When I finally got home I discovered that my voltage regulator had burnt up. By the looks of things I assumed I could just get a new one put it in and be fine. However, once I installed the new one there were some issues. The motor had no spark. After investigating and trying things the only way to get it to run is to spray contact cleaner on the optical sensor. Once applied the engine will then start. I got the sensor out and it appears that it is fogged up somewhat and when sprayed with the cleaner it clears up. Once running it will only run for so long before revving up and then shutting off. That is where things become interesting too because my girlfriend said that just before I turned the motor off when it was smoking that it revved up like it is doing now. Sorry for the long post, I just assumed these details would all be very helpful if anyone has any possible ideas as to what has happened?

 

[Chris1956]

The dry chemical in a fire extinguisher is real caustic. It corrodes everything it touches. Make sure you wash it off of everything. Maybe it fogged the optical sensor?

 

[z.fields27]

The dry chemical in a fire extinguisher is real caustic. It corrodes everything it touches. Make sure you wash it off of everything. Maybe it fogged the optical senso

I've got it cleaned up pretty good now. That's kind of what I though could be going on by the looks of it when I pulled it. I could get the sensor out again and post a picture and see what you think. I hate to just buy parts without knowing for sure what's going on.

 

[racerone]

If it revs up before stalling , I think it is running out of fuel.

 

[saltchuckmatt]

Try pumping the primer ball as it starts to die....if it runs look at or fix the fuel pump.

As far as the sensor....replace it.

 

[z.fields27]

If it revs up before stalling , I think it is running out of fuel.

The problem is I have to spray contact cleaner on the sensor for it to even run. I took the sensor off and sprayed it and tried to clean it up, when you do this in just a few minutes its fogs back up with the residue thats still hanging around from the fire extinguisher. I believe that is whats making it shut off. Maybe thats a flawed idea tho.

 

[z.fields27]

Try pumping the primer ball as it starts to die....if it runs look at or fix the fuel pump.

As far as the sensor....replace it.

It’s not like a slow die off. It just shuts immediately off, there isn’t really a way for me to know when to pump the primer unless ai just did it the entire time. Just got off the phone with a dealer near me and they actually have the sensor in stock. I think I am going to go get it and go from there.

 

[Faztbullet]

Dont replace it till 100% of the dry chemical is gone from engine

 

[z.fields27]

So I got ahold of the new sensor this evening. Made sure everything was good and cleaned up and put it on. Started the motor on the muffs and it ran fantastic. I had absolutely no issues like before. I then decided to run to the river to fish a little before dark. I probably ran the boat for 4 or 5 miles round trip. The only odd thing I noticed while out was that my tachometer stopped working. I loaded the boat up and was strapping the boat to the trailer when I smelled something burning up once again. I disconnected the battery and took the cowling off to once again find my voltage regulator smoking. Not sure where to go at this point, could it be my stator going bad? I appreciate any ideas.

 

[z.fields27]

Ive been brainstorming ideas and I’m wondering if my impeller were bad if this could cause the voltage regulator to burn up? I know that it is water cooled and if it wasn't pumping enough water to get to the regulator maybe that could be the cause to burning up 2 in such a short time.

 

[saltchuckmatt]

Not sure but possibly. Pull the hose when it's running and see if it's getting water. If it's not hooked to a battery or hooked up wrong that will burn them up as well.

 

[jonesg]

I loaded the boat up and was strapping the boat to the trailer when I smelled something burning up once again. I disconnected the battery and took the cowling off to once again find my voltage regulator smoking. Not sure where to go at this point, could it be my stator going bad? I appreciate any ideas.

its electrical, not water cooling related.
Do you have any sort of quick connects on the battery terminals?

 

[Faztbullet]

A weak impeller will cause rect/reg failures due to it overheating at slow speeds. Water does not fully fill the block cavity to reach heat sink fins. Rectifier is then damaged internally then fails.

 

[cyclops222]

If your rectifier has a very flat smooth bottom that bolts to a very flat smooth engine surface ? You must coat the rectifier surface with a ...Heat Transfer .... grease compound. It will keep the rectifier from cooking to death.
If your battery is TOO RUN DOWN ? It can kill the rectifiers. Been there on that problem.

 

[racerone]

????-----The rectifier on this motor is water cooled.-----Bottom surface is exposed to water !

 

[cyclops222]

Off with my head.