1973 65 hp johnson

[boatin12]

hi all i have a 1973 65 hp johnson and i just rebuilt all carbs and did a water pump change along with the thermostat it starts and runs great for about 5 minutes or so then it dies.i put muffs on when i got home and it runs forever but when its in the lake it only runs for about 5 mins.im lost any help is appreciated!

 

[JB]

Re: 1973 65 hp johnson

Seems that something is getting hot and failing. On the muffs there is no load, so it doesn't get hot.

I would take the cowl off and while running on the muffs use a hair dryer to heat up parts to see if I could make it fail. It is likely to be a part that is common to all 3 cylinders and in the ignition system.

Good luck and let us know what you find.

 

[boatin12]

Re: 1973 65 hp johnson

Ok I put it in a barrel this time let it run for 20 mins at idle speed seems to be fine no evidence of over heating I could touch the block with my hand for about 10 seconds or so. It ran long enough to warm the water in the barrel. So I'm not thinkin it electrical either.would using a barrel be sufficent to bein in the lake? Also I did find water leaking from the port side where the ground wire is connected so I tightened the bolt and the water stopped would this cause it to fail?

 

[JB]

Re: 1973 65 hp johnson

You need to read my post again, boatin. Use a hair dryer or heat gun to heat it up.

 

[boatin12]

Re: 1973 65 hp johnson

Sorry jb I did do as you said and it still ran fine maybe ill lake test it again tomorrow

 

[tx1961whaler]

Re: 1973 65 hp johnson

On the lake, when it starts to die pump the primer bulb and see if it picks back up.

 

[boatin12]

Re: 1973 65 hp johnson

Ok got out on the lake today and the bulb seemed to go soft after running for a bit is this correct?

 

[tx1961whaler]

Re: 1973 65 hp johnson

Soft is fine. Sucked completely flat is not.