150 Ocean Runner losing power when warm

[v12mac]

Any one have any Ideas on this?<br />I am helping a buddy with a Johnson 150 Ocean Runner; it fires right up cold and runs fine. When it gets up on plane after 10-15 min it looses power and drops down to a very rough fast idle. There are no alarms signaled. The engine has oil and a good cool stream of water out the “Pisser”. So far we have replaced the water pump and the fuel filter / water separator. Right after we did the water pump and fuel filter it ran fine for a full day. <br />Any ideas where to check?<br /><br />Mac

 

[ob]

Re: 150 Ocean Runner losing power when warm

First thing I would do is to test the overheat alarm circuit for operation.With the key in the "on" position locate one of the tan temp sensor wires and ground to the engine block.Continuous alarm should sound.Were the T/stats replaced along with the waterpump?Sounds like it may be going into the S.L.O.W. mode .<br /><br />After engine drops off ,can you get it back up to speed again before it drops back off?Have you tried bumping the primer button when egine is falling off to see if it responds.Is fuel tank venting properly and primer bulb not colapsing?

 

[v12mac]

Re: 150 Ocean Runner losing power when warm

Thanks for the quick reply.<br />Looking at the heads there are sensors on each side. One has only 1 wire and one has 2 wires. Do you know if they are both temp sensors?<br />Mac

 

[ob]

Re: 150 Ocean Runner losing power when warm

Yep.Both are temp sensors and one with the two wires is the one that initiates quickstart and s.l.o.w.<br />Do you get the initial test chirp when the key is turned on?

 

[v12mac]

Re: 150 Ocean Runner losing power when warm

Yes I get the single test chirp. <br />Question, I am concerned that this may be an oil problem putting the motor in the slow mode, how can I make sure the oil injection is working? I don’t want to eat up the motor fiddling with the cooling system.

 

[G DANE]

Re: 150 Ocean Runner losing power when warm

V12mac<br /><br />Start premixing oil and fuel in 1:50 right away. Mark the level on oil tank with speedmarker and observe oil consumpsion. That way you wount damage anything and the extra oil wont hurt anything. I might be a good idea to backflush cooling system if an impeller vane was lost.

 

[ob]

Re: 150 Ocean Runner losing power when warm

You can insure oil usage by keeping a line marked on the side of the oil reservoir and noting whether it has dropped.Calculate the oil usage verses fuel consumption.Also make sure the the pickup sock in the oil reservoir is clean and clear and the oil primer bulb stays firm.You could reprime the oil line up to the vro pump by disconnecting it at the pump and repriming until a solid flow is noted and then reconnecting.Any time the oil sysytem is serviced or reprimed ,it is required that you mix 100/1 in the fuel tank until you can verify oil usage from the oil reservoir.The only sensor that initiates the s.l.o.w. is the overtemp sensor.However,It has not been established that the engine is going into the s.l.o.w. mode.<br /><br />What do the sparkplugs look like after a water run? Do they have oil residue on them or are they dry?They should be at least damp with oil residue.According to your symptoms ,I don't feel you are chasing an oiling issue ,but rather an overheat or intermittent igniton failure.In order for me to assist any further ,you'll need to answer the questions posed in my earlier replies.Trouble shooting is a process of elimination procedure.

 

[v12mac]

Re: 150 Ocean Runner losing power when warm

Thank you all for the ideas. I’ll get out there today (got to sneak out of the office first) and run through the steeps you have outlined. <br />Mac

 

[Hooty]

Re: 150 Ocean Runner losing power when warm

You said you were getting a "good cool stream of water out the pisser". That water should be nice and warm. Has someone removed the thermostats? Do the heads feel warm or cool?<br /><br />c/6<br />Hooty

 

[v12mac]

Re: 150 Ocean Runner losing power when warm

I tested the alarm and it works fine. But when I pulled the spark plugs, the bottom two cylinders seemed extra oily. I also noticed that they share a coil pack. Any ideas?

 

[v12mac]

Re: 150 Ocean Runner losing power when warm

New info! <br />I found that when this occors I am loosing spark to the port side bank of cylinders. How could I be loosing spark to one side of the engine?

 

[Walker]

Re: 150 Ocean Runner losing power when warm

The SLOW system will cut off one bank when it activates. You need to make sure your motor is not overheating before you do anything else. To test the Slow systen you disconnect the heat senson wires on the side with a tan/blu and white/black wires. If its the SLOW system causing the shut-down you will have fire to both banks again.

 

[v12mac]

Re: 150 Ocean Runner losing power when warm

I tested the temp sensor / grnd the tan wire and it rang the horn. So I figured that the problem might be the power pack. I installed a new one and a new set of plugs while I was at it and it seems to be running great. I’ll let you know if it keeps working.<br /><br />Hooty, I don’t know if anyone has messed with the thermostats. Boat and motor were purchased used. When the engine is running heads are warm but not hot. I can touch them but can’t hold my hand on for more than a few seconds.<br />Mac

 

[Hooty]

Re: 150 Ocean Runner losing power when warm

The temp you're describing (hand on heads) is about 135*-140* which is ok.<br /><br />c/6<br />Hooty