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johnson 1967 5hp Lack of power and stopped running

A

alanozzy

New member
I would be grateful of any help I can get I’ve got a Johnson 5hp 1967 model number C512450--- LD-12A engine the outboard runs for a short time and at low speed then it just stops I’ve had the plugs out and there wet and black and also there is black oil running down the exhaust outlets the mixture I’m using is 50.1 I would appreciate any help thanks
 
Re: johnson 5hp Lack of power and stopped running

Have you looked at the water pump impeller.-----------------------Do a compression test.---------------------Check to make sure the ignition can fire a spark accross a 1/4" gap.-----------------These motors are famous for cracked ( shorted out to ground ) ignition coils and it might be a good idea to pull the flywheel to inspect the 2 coils.
 
It's took some time to track down some coils for this outboard but now I have replace the coils and it seems to be runnin okay the fuel mixture I am using at the minutes is 50.1 would this be about right for this type of outboard many thanks
 
Those coils are known to be bad and used on all small OMC motors from about 1950 up to the late 80's. ----Any good shop will have them " in stock "------There will always be places that say " too old a motor , can't get those coils " which of course is nonsense !-------Have you checked to see if the thermostat is in place and working ?---------They are often found " stuck open "--------------------50:1 is the mixture to be used in that motor !!!!!
 
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Hi racerone
thanks for your reply its a good job you mentioned about the thermostat I took the thermostat housing apart and there wasn’t a thermostat in it while the thermostat cap was off I fired it up to see if any water was coming up there wasn’t ???? I’ve checked the condition of the impeller and it looks new please can you advice on what steps to take next
many thanks Alan
 
Many thanks racerone you was spot on you know your stuff I didn't fill by bin full enough at the moment I've just left it ticking over in the bin which is now full with water it seems quite happy just ticking over there
there seems to be a fair bit of black oil is that normal ?????
 
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