Johnson Motor Cutting out

[ljjonesy]

Need a solution to a ongoing problem with our Johnson 72 model electric shift (50th Anniversary series).<br />When going along at planing speed (approx. 3,000 revs and above) the motor cuts out for a split second and then restarts itself. This can happen five time or more in 30 mins running.<br />Cant find answer in Australia.<br />Have re-fitted new distributor cap but still cuts out. Can someone please help as this problem is now five years old and my friends are living in fear of being thrown out of the boat!!!!!<br />Thanks

 

[steelespike]

Re: Johnson Motor Cutting out

I would check the killswitch circuit it may be<br />shorting to ground somewhere.<br /> Most motors run with killswitch open and stop with kill switch closed to ground.<br /> We need model number and what you have tried so far.

 

[ljjonesy]

Re: Johnson Motor Cutting out

Thanks for your reply - <br />Model number - 100ESL72<br />Will talk to my father about what he has done to the engine so far.

 

[bryanredfish]

Re: Johnson Motor Cutting out

I know this is a silly question, but have you checked the spark plug wires? Same thing happened to me, and I couldn't find the problem UNTIL I started it at night with cowling off. A defective wire was sparking off the head. The wires looked perfect, otherwise. Also, it wouldn't happen until the plugs warmed up, which could explain why it's happening at higher RPM's.

 

[Jim@KSC]

Re: Johnson Motor Cutting out

Good troubleshooting clue, bryanredfish.

 

[Dhadley]

Re: Johnson Motor Cutting out

You said you have a new distributor car - what about the rotor? Is the spring washer on the rotor? Look at the reverse cut-off spring. If it has been replaced because the old one was worn in pieces, an old piece may be touching and grounding the ignition momentarily. Take the distributor base plate off and look at the wires on the bottom side of it. There is a plate over them and sometimes they wear through and can short out aginst the plate. <br /><br />There were some bulletins out about the sensor ring. Make sure you have the right one. They can test the sensor also. <br /><br />The battery is very important in these systems also. It must be at least 72 amp hour (if I remember correctly) but we always had better luck with at least an 85 amp hour battery. <br /><br />This is all based on you saying the motor "shuts off" momentarily. You sure its not jumping in and out of gear?<br /><br />Good luck!

 

[Brian J Jones]

Re: Johnson Motor Cutting out

Jonesy 4445 - That 100HP Johnson 1972 Model has had a new Distributor Cap and Rotor fitted, along with a new Reverse cut-off spring. We re-newed the leg oil twice in 24 hours. Another problem - maybe it's related to the cutting out at speed - is slipping out of gear at idle speed, and having to restart the motor to get it back into gear.<br />The suggestion of bryanredfish is elementary and excellent.Will replace leads.<br />I'm just adding to the info, as I'm your Father.<br />The battery is new - 85amp hr.<br />When the motor cuts out for that second, the revs drop from 3500 to 2500 then increase when the motor reignites.<br />Hoping for any confirmation of plug lead suggestion or any other advice. Would it be the pulse pack?

 

[Joe Reeves]

Re: Johnson Motor Cutting out

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[Joe Reeves]

Re: Johnson Motor Cutting out

Jonesy.... You don't say what lube you're using but... the lower unit on that model is a Hydro Electric Shift model and CANNOT USE the standard HiVis 80/90w lube that is used in all mechanical shift units. You must use what is called "Premium Blend", also know as "Type C". The standard HiVis lube is too thick and will cause erratic shifting due to the fact that the oil pump within the lower unit is not designed for that viscosity.

 

[Brian J Jones]

Re: Johnson Motor Cutting out

Thanks Joe Reeves - But yes - the leg oil used was Type C for electric shift.<br />All replacements etc have been carried out by professional OMC mechanics.<br />Thanks for your interest.

 

[ob]

Re: Johnson Motor Cutting out

Jonesy, When you say motor cuts out and restarts itself if you are not positive that this is an ignition issue I would take a close look at the entire fuel delivery system.Start with tank and work up to carbs.<br />Is fuel tank venting properly?<br />Inspect or remove anti syphon valve on tank fitting.They are notorious for sticking.<br />When you purge fuel system before startup while pumping primer inspect for leaks on suction side of pump.<br />When engine begins to stumble is the primer bulb colapsing?

 

[Joe Reeves]

Re: Johnson Motor Cutting out

Jonesy.... You don't say in this post or a previous one whether the momentarily type shut down is a slow gradual (fuel) shut down or a very quick sudden (ignition) type shut down. However your remark about having someone possibly being thrown from the boat leads me to believe that the problem is a sudden cut off/cut in type problem.<br /><br />In which case, it could be something as simple as a frayed 12v power wire leading into the engine cowling, the turning of the engine causing a make/break type connection.<br /><br />Suggestion..... with the ignition key on, hook up a voltmeter to the 12v power wire leading to the powerpack at the terminal strip, then start moving wires which would include the main harness leading to the engine.... A movement of the meter reading = a broken wire. Worth a try.

 

[Brian J Jones]

Re: Johnson Motor Cutting out

Thanks Joe Reeves - I'll do that test of the Power pack in the next few days.<br />The very sudden on/off of the motor really does point to electrical problem rather than fuel. --- I guess I'll have to do the spark plug leads along with the test of the main 12V and Loom with the Multi meter before I invest in a Pulse Pack ???<br />I have brushed with solvent every wire connection that is visible - including the wires within the remote control box - to assure a good connection. will still persist.

 

[ajp]

Re: Johnson Motor Cutting out

My 1969 Johnson 115hp had a similar problem. Was running fine after fixing a problem with the wiring of the airgap sensor, then it just cut, the motor immediately took off again. Then again, and again, after several minutes of tooling around it wouldn't run at all. We pulled the flywheel and found the sensor gap was not set at .028. Must have slipped. We reset that and it has worked great for a couple of fishing trips.

 

[gmcleary]

Re: Johnson Motor Cutting out

My 40 horse Johnson had similar problem, turned out that a hair line crack inside the coil would cause the same sympton to occur for me when he engine became warm. If you remove the coil, a decent auto electrical shop will be able to bench test it.<br /><br />good luck

 

[mattttt25]

Re: Johnson Motor Cutting out

i know the more knowledgable folks say the symptoms point to an electrical problem, but a buddy had the same problem you describe with his '96 150hp johnson (not fun riding in a center console that goes from 35mph to nothing real fast!). i don't know what the mechanic did to fix, but it was definitely a fuel delivery problem. i know that's not much help, but if all else fails, look there. good luck-

 

[rickdb1boat]

Re: Johnson Motor Cutting out

Matt's right on that one. I've had it happen and it will stop DEAD in the water. This is especially true if you are running at high speed and a restriction occurs. Just my experience.