71 Johnson 60 HP does not restart

[jksnyder]

I wonder if anyone could comment on the following: I have a '71 Johnson 60HP which runs fine at high speed for any length of time, but when I slow to idle ( after the engine has run for 10 min or more) it simply quits and will not restart until cooled down. Is it at all possible that incorrect spark plugs could cause this problem?? How about stator problem? Any thoughts or ideas you could share will be most appreciated. Jay

 

[Tim Frank]

Re: 71 Johnson 60 HP does not restart

The basic symptoms sound like the power pack is shot.

 

[jksnyder]

Re: 71 Johnson 60 HP does not restart

The basic symptoms sound like the power pack is shot.

Yes, but I did replace the power pack last year. Thanks for the thought. J

 

[tashasdaddy]

Re: 71 Johnson 60 HP does not restart

you should be running Champion QL77JC4 gapped at .030. i would suggest checking spark immediately when it does this.. the only way to tell. i really don't think it is power pack or stator, as these would fail when they got hot, and not wait for you to stop. are you sure the vent is open on the fuel tank. could be the vent is clogged, the fuel pump is able to pull fuel as long as it is running fast, but when you stop, it can't.

 

[Tim Frank]

Re: 71 Johnson 60 HP does not restart

I had a 1969 Johnson 55 that had the same symptoms.
This was the early OMC venture into CID ignition and shall we say was not without its foibles.
These engines had a tendency to develop an appetite for power packs/amplifiers. As often as not this would also take out the rectifier.
Mechanically these were fine engines, but the electrics provided me with years of ongoing adventure, particularly when starting.

My money is still on the ignition system...my #1 suspect is the power pack...#2 would be the coil. The fact that you replaced a power pack last year suggests that there may be a root cause elsewhere in the ignition system.
Does your 60 HP have the BHP (big honking plug) in the main harness inside the engine cover? These are a major cause of problems as the wiring deteriorates....insulation breaks down....resistance increases etc. etc.

Best maintenance advice I ever got was from a guy who runs a repair shop in Florida. He told me to go over all the wiring in the harness inside the motor, replace anything that was suspect, and GET RID of the BHP. I made all the connections with ring connectors and heat-shrink tubing, on a terminal board. For the rest of its service life it ran better than original. Sure starts, and no more power pack failure.

Any good service manual will give the troubleshooting steps to verify these components. If you don't have the equipment/tools most good repair shops can test the components. You can remove the mounting plate and take the whole thing to the shop.
Be sure to do at least a visual on the internal wiring, paying particular attention to the condition of insulation especially at the BHP. After 30 +years this could be a trouble point.

 

[jksnyder]

Re: 71 Johnson 60 HP does not restart

Thankyou....that's good advice. What is the BHP and how does it function?
I do see the so called big hunk. Jay

 

[jksnyder]

Re: 71 Johnson 60 HP does not restart

I do have the plugs you mention. I have an internal 10 gal. tank which vents to the side of the boat which is clear. Many thanks for your comments. This engine has very few hours on it.....at high speed it runs like a charm. Does not idle well ever, but as I said after running for more than 15 minutes it won't start until cooled off. Water pump seems to work fine...temp of water discharge is not abnormally warm or hot. Since this engine ('71) matches the age of the 16' aluminum boat and was the original purchased package I'd like to keep it, but not interested in forking out a lot of $ just for nostalgia.
I'm hoping to find a fix of this problem since overall it runs great. Also one other small problem is that it smokes a lot...even on 50:1 ratio.

 

[tashasdaddy]

Re: 71 Johnson 60 HP does not restart

The BHP. is the big electrical plug where the wiring harness from the control, connects to the motor. it will smoke a lot in neutral, you could change to synthetic TC-W3 oil. also could do a decarb, and get the carbon out of the motor.

have you check your compression, cold and hot?

Decarb, take a can of seafoam put 3/4 of it in the gas tank, with only 1 gallon of premixed gas. put the rest in a spray bottle. start the engine, and let it come up to temperature. then remove plugs, and them some real good shot of seafoam into the cylinders, replace plugs, let sit 15 minutes. restart, and spray the rest of the seafoam into the carbs, so the the motor almost stalls, wait and repeat until the seafoam is gone.then take for a wide open spin. then put in new plugs, ad premixed gas to the tank, and take it for a wide open throttle spin. it is going to smoke like a house on fire, during this process.

afterwards compression.recheck

 

[Tim Frank]

Re: 71 Johnson 60 HP does not restart

Jay,
Sorry, looks like my attempt at humour was a bit confusing.
The "BHP" is my acronym for Big-Honking-Plug and is in no way a technical term or description.

As Tashasdaddy said, it is indeed the big plug that connects the interior engine wiring harness to the main harness in the boat. It has a lot of small pin connectors that are susceptible to corrosion and can be a real source of poor connection and trouble. In addition, if the motor is/was removed frequently, there would be more stress on the wires right at the point where they enter that moulded plug. The insulation is particularly prone to deteroration right in that area.

I don't think that you commented or answered Tashasdaddy's questions on plugs and spark testing which are bang on. Any chance that you have the wrong plugs and /or gap?
Next, you really want to nail down whether you have a fuel problem or a spark problem when the motor dies out on you......look at the answer to that as potentially cutting your troubleshooting by 1/2.
My experience with that vintage of OMC is that you would probably still have spark, just not a strong enough spark. SDo it can be pretty subjective trying to eyeball the quality of the spark unless you have a proper tester.
One way to do a quick and dirty test would be to take along a can of freeze test spray (available at most electronics stores) and when the motor dies give a few shots to the power pack and see if the motor starts right up.This should cool that copmponent rapidly and simulate the cool-down that you have required. If the power pack does not offer any change, try the coil.

 

[jksnyder]

Re: 71 Johnson 60 HP does not restart

Thank you all for your comments....I'm not only encouraged to find the answer but impressed with your depth of knowledge and suggestions. As cold temperatures are fast approaching here in VT I'm sure how much longer I have for these tests. I hope to get the engine quirks corrected before put to bed. I'll certainly let you know if any results. Thanks again.