94 Johnson 150 stops running after 30 minutes

3

3gun

Cadet
Joined
Aug 18, 2004
Messages
15
After about 30 minutes of running on plane, my 1994 Johnson 150 Ocean Runner just stops dead. When running, it runs fine and starts easy. After a few hours, it starts again but runs for less time. No alarms sound and both temp sensors sound when the wires are shorted. So far, I've replaced the water pump and both thermostats believing this was an overheating problem. I've instected all the connectors on top and having to do with the power pack. Could a defective powerpack cause these symptoms? Thanks.
 
Joe Reeves

Joe Reeves

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Feb 24, 2002
Messages
13,262
Re: 94 Johnson 150 stops running after 30 minutes

It's possible that you have an intermitent short within the ignition switch. Remove the Black/Yellow wire from the switch. If the problem is now non-existent, replace the switch.<br /><br />Note that the engine can not be shut down via the ignition switch with that black/yellow wire being removed.<br /><br />If the problem still exists, check the stator under the flywheel. If the large black coils are dripping a sticky substance down onto the block, that would indicate that the beginning of the ignition circuit is faulty. In which case, replace the stator.<br /><br />The black coils supply approximately 300 AC volts to the powerpack. When they melt down, the ignition becomes erratic and eventually fails altogether.
 
JB

JB

Honorary Moderator Emeritus
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45,907
Re: 94 Johnson 150 stops running after 30 minutes

Hi, 3gun.<br /><br />Welcome to iboats. :) <br /><br />Sounds to me like your powerpack is failing when it gets warmed up.<br /><br />To test my theory, crank the engine on the muffs with the bonnet off. Use a hair dryer to heat the powerpack and see if that kills it. You can then chill it with cold spray (available at electronics stores like radio Shack) and see if she fires back up.<br /><br />Good luck. :)
 
S

seahorse5

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Re: 94 Johnson 150 stops running after 30 minutes

It could be the pack, but as long as you are sure that there is no spark, replace the OIS sensor (electric eye) first, or have it tested while warmed up, since it is easy to change out and it only around $50.
 
3

3gun

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Aug 18, 2004
Messages
15
Re: 94 Johnson 150 stops running after 30 minutes

Thanks for all the replies. I was able to borrow a powerpack and plan to run it tomorrow. Can an overheated engine cause the motor to cut out without a alarm sounding? I'm sure the alarm works for both sensor.
 
3

3gun

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Aug 18, 2004
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Re: 94 Johnson 150 stops running after 30 minutes

With the new powerpack on it did the exact same thing. After about 30 minutes, the motor stalls out and then wont start. No spark. Its not overheating and the overheat sensor wire are disconnected and so is the kill switch wire. I want to inspect the stator under the flywheel as Joe R. suggested. Do I really need to lock the #1 piston as the Clymer manual states? Or, should I let a pro take it from here?
 
3

3gun

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Aug 18, 2004
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Re: 94 Johnson 150 stops running after 30 minutes

Seahorse! It was the OIS sensor that was bad. Replaced it and went fishing Saturday running for a total of 4 hours. Replacing this part also fixed another problem I had been wondering about. After starting, I would have to keep pressing the key to keep the engine chocked for several minutes. No more. The sensor had something to do with the faststart, I guess. Thanks again.
 
A

agood1

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Sep 8, 2004
Messages
46
Re: 94 Johnson 150 stops running after 30 minutes

What and where is the OIS sensor...I have the same problem. Thanks
 
3

3gun

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Aug 18, 2004
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Re: 94 Johnson 150 stops running after 30 minutes

The timing sensor(actually two sensors) works in conjunction with the timing wheel to provide two timing signals. One signal for each rev and the other is 6 signals per rev. (from the OMC manual)<br /><br />The timing sensor is located under the timing cover which is located on the very top of the engine. The timing cover is held by 3 screws. Once removed you will see the timing wheel and the timing sensor is under the timing wheel at about the 1 o'clock position, you will see the connector. According to the OMC manual, you will need a Piston Stop Tool to remove the timing wheel correctly. I took it to an OMC mechnic and had him change it. $62 for the part. Unfortunatly I had to leave it and was unable to watch. So thats all I know. Perhaps Seahorse could fill you in on further details.
 
A

agood1

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Sep 8, 2004
Messages
46
Re: 94 Johnson 150 stops running after 30 minutes

Now I am wondering if I have an OIS sensor...does a 90hp V4 1990 model have an OIS sensor?
 
P

Pst76

Petty Officer 1st Class
Joined
Aug 11, 2002
Messages
220
Re: 94 Johnson 150 stops running after 30 minutes

Have replaced OIS sensor on my 92 150 after same symtoms. I now keep a new spare one added to my tools on the boat. Takes about 10 min to change. Of course now that I have a spare it will probably never act up again....
 
3

3gun

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Aug 18, 2004
Messages
15
Re: 94 Johnson 150 stops running after 30 minutes

PST, do you need special tools as outlined in the OMC manual or can you just remove the nut that holds the timing wheel and replace the sensor?
 
S

seahorse5

Rear Admiral
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Jan 24, 2002
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Re: 94 Johnson 150 stops running after 30 minutes

Agood1,<br />Your 1990 motor does NOT have OIS ignition.<br /><br />3Gun,<br />You do not need the piston stop tool. You can put the motor in gear and hold the prop with your foot to loosen and torque the timing wheel bolt.
 
A

agood1

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Sep 8, 2004
Messages
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Re: 94 Johnson 150 stops running after 30 minutes

Thanks seahorse...pleae take a look at my latest post about getting towed in and let me know if you have any suggestions.
 
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