Hi. I am having problems with my 1982 70hp Johnson.
This is what happened last weekend: Started right up, then overheat alarm came on, lowered the idle; it cooled & alarm stopped. The tell-tale was pumping water fine, so I headed out in a no wake zone. Once I passed the no-wake, I opened it up, the motor bogged down and died. It wouldn't re-start.
The fuel is new, tank is clean, correct oil mixture, fuel line new with inline filter and water separator, fuel pump recently rebuilt. The bulb goes slightly soft from time to time, but can't find an air leak. Everything seems tight.
I pulled the plugs and noticed that they were fouled with black greasy fuel. Also, there's black greasy fuel mix leaking out of the hub exhaust.
I plan to change the plugs and attempt to restart on the muffs. Should I check anything else? What is up with the sludge from the exhaust?
This is what I would do is first get you or borrow a compression tester and test your compression to see what pressure the cylinders are at and if that is good, say 100 PSI and within 10% of each other then you need to change out the water pump and get a new thermostat or you can test the thermostat in a pan of boiling water and see if it opens whent the water is boiling it should open up at 143 degress . Also, if you haven't did them you need to rebuild your carbs and make sure every single orifice/jet is clean and clear and use compressed air to blow those jets/orifices out and put the carbs back together correctly. Make sure you use brand new carb kits and set the floats exactly what the intsructions say. I onw a 1983, model# J70ELCTE, 70 horse Johnson outboard and did this to mine. In fact since I was having an idle/stall issue I went and replaced all of my fuel lines including installing a genuine Johnson/Evinrude fuel primer bulb line that cost me $50.00 with taxes and rebuilt my carbs again. I rebuilt my carbs last year and when I went to open mine up my nozzle gasket was cut becuase I torqued the float bowl screws down way too much and I think not 100% sure that that is was my idling issue along with a partially kinked main fuel line comming from the engine connector to the inlet on the fuel pump. I also found after installing my carbs that the bottom carb was out of adjustment some what because when I installed my link rod to all the carbs I had to move the butterfly to line up with the rod and the middle and top carb was fully closed when it is sitting at idle/nuetral so I adjusted the bottom carb to allow the butterfly to be completely closed with the center and top carb at idle/nuetral. I also cranked her up and she is running good and seems easier to crank now then it did before and I didn't have to raise the warm up lever to full throttle so I am thinking I will be fine now. All in all I am happy with my motor and you will see it is a good motor and should served you well. Let us know how it goes with your motor. Take care, Bob