150 johnson electrical problem

[crfab]

Hello,
I have a 150 johnson that is loosing fire. took it out yesterday and it started great as usual while slow idling to fishing hole the engine dies like shutting off key. It did this several times before finally continuing to run. Got to point and fished for a time then decided to move we went to next spot and this thing ran like a top. headed to next spot got boat up and running and it started shutting on and off like the key was being turned off and on. it did this for about 5 to six times when I would try to take off it would go then die or just cut in and then out again. I sat there for a moment trying to figure it out and decided to try it once more. it took off like a new one. We ran it for about 5 miles up the lake turned around came back and it never missed another beat even after stoping to fish another spot ran like a top. Does anyone have an idea what could be going on with this thing. I have posted other problems with this engine and had success with answers. have already replaced the pack checked ignition by unpluging large connection at engine and jumping from the red wire to the yellow it restarted doing this but died a few seconds later. so whatever it is seems to be at the engine. Thanks ahead of time for any help.
Robby

 

[Walker]

Re: 150 johnson electrical problem

You need to do a spark test when it acts up to be sure you have an ignition problem. Without definitive proof you are just chasing your own tail.

 

[dgawoski]

Re: 150 johnson electrical problem

That sounds like my engine before replacing the power pack. Since you already replaced this, start by checking your ignition key switch and kill switch functions, and idle shift switch contacts. CDI electronics has a good trouble shooting guide for these engines:
http://www.cdielectronics.com/downloads/troubleshooting guide/OMC 6 Cylinder Optical.pdf
It could be circuits on the stator, or the rectifier. You can perform some of the tests with a shop manual and regular multimeter, and that might pinpoint the problem. For voltage tests you will need to get a peak reading digital multi-meter with DVA adapter.

 

[keefallan]

Re: 150 johnson electrical problem

Check your wires for frays or shorts. Wiggle them etc. Your engine shuts off by grounding out the power pack. Disconnect the ground wire and check it to ground with a continuity test. It should not be grounded. If it is, replace it. Check to see if the other end of the wire(harness side) is grounded(might be intermittant).

 

[jonesg]

Re: 150 johnson electrical problem

Year and model number might help.