what happened??

[alumapompano]

I have a 84 70 hp Johnson.. Brought it out last sat and sun ran great....Until the last ten minutes ..Stopped to fish for about twenty minutes.. Turned the engine back on, it cranked but would not start. Finally got it started with the warm up lever, but idled awful and when you put it in gear it would stall. Had to end up using the trolling motor to get in...I have a theory about what happened . I never started from o when filling the 6 gallon tank. Had half a tank on the second day ,I just refilled the tank up ,not lookin at how many gallons I put in . Then I Put 8 fl oz more in the tank. Not knowing how much oil was still in there .. I also pulled the plugs when I got home .They were fouled with oil.... I have replaced the plugs and got the rite mixture now . It starts now ,and works in gear , but Im still not sure if I fixed the issue.... Any suggestions would be more than welcome...:facepalm:

 

[phillnjack2]

Re: what happened??

i think the fouled plugs told you what happened.
too much oil in the fuel.
it ran good untill it got down a touch then the plugs started to foul, then they got realy fouled when you
tried to start it on the strong oil mixture,even worse if you used the choke/primer !!!!!!.

fresh juice clean plugs and back to normal.
sounds about right to me


phill

 

[OptsyEagle]

Re: what happened??

Well it sounds like you were fairly close to the right formulation. 8 oz of oil to around 3 gallons of gas. I am pretty sure if you doubled the amount of oil you needed it would not have caused any running problems. Remember, whatever you did with the oil, it was diluted by the gas mixture that was already in the tank.

Whenever, you are having starting problems, unless they are caused by the engine not receiving fuel, you are going to have some very wet spark plugs from all the fuel that didn't get ignited. So no, I doubt that was your problem, but if it is running OK now, it will be difficult to find out what your problem was. You could always do the basic compression and spark test, or you could simply run it and see if the problem returns.

Also, it seems to me that all you did was change the plugs and your motor was fine so perhaps the plugs did foul. Plugs don't foul because you have to much oil in comparison to the amount of gas, they foul because you have too much oil and gas in comparison to the amount of air. Perhaps your motor is running too rich. You could reset the carb/s low speed adjust to verify that it is set properly. You could also verify that the T-stat is not stuck open. Also, were you trolling with the motor a lot that day or any day. Verify that you are using the correct spark plugs (Champion QL77J4C). When was the last time the motor was decarbed?

 

[alumapompano]

Re: what happened??

I have champions L77JC4. The Q is for the marine ones right? The last hour I did stop and start the motor a little to get into a spot...I don't troll with the motor though, I have a trolling motor....Engine carbs were cleaned last year...The spark plugs did show wet oil.. will check the carbs low speed adjust.. Then go from there.. Thanks guys......