Need Info on 9.5 johnson

[Timbit]

just bought a boat with this motor on it. it only runs at full choke. i changed the plugs and filled the tank with fresh gas/oil, with a 50:1 mix. the motor will idle with full choke but only after about 10 mins of running. does anyone have any ideas of how i can go about fixing this?<br />Also I need the year of this motor, proper plugs, gap etc..<br />Model # MQ-10R

 

[Crankstomp]

Re: Need Info on 9.5 johnson

It is a 1964. Plugs are champion J4C gapped at .30 according to the book, but I've heard some guys gap them wider. If it will only run on choke, it's because the mixture is too lean. Has it been sitting for long? If so, the idle jets are probably gummed up. If not, your idle mixture setting may be off. There are good posts on here describing how to set your mixture screws, just use the search feature.

 

[Timbit]

Re: Need Info on 9.5 johnson

Thanks for the info Crankstomp

 

[wayne h]

Re: Need Info on 9.5 johnson

all parts are still avalable for the motor i have about 4 of them and love them all they are simple little motors but get a manual look on eday u can get a factory service motor for it and will help out alot. i would go though the carb and mabe the fuel pump. if you do it yourself it will be about 30 buxs if that also service the waterpump if u dont know the last time that was done.u can do a complete tune up on that old dog and she will last another 30 years before u do all that run a comprestion test that will tell you alot right there they sould be within 10% of eachother. psi depends on who u ask i have seen them run great at 60 psi with is alittle low but i still use the motor every sunday with no problems. let us know what u come up with and good luck

 

[Timbit]

Re: Need Info on 9.5 johnson

I cleaned out the fuel pump and changed the plugs and gapped them to .30 and set the idle mixture properly. it ran great on monday and thursday of last week, so i took it up to my cottage. this morning when i went fishing it ran good until i was trolling for about 1/2 hour or so then it quit on me. it took quite a few pulls to get it started again, only to quit again about 10 mins later. what should i do now?? it runs great at wide open but not at slow speeds.

 

[OBJ]

Re: Need Info on 9.5 johnson

Hi Tim.....running at WOT throttle and running poor at low end really indicates a carb problem or poor spark.<br /><br />Test the spark by rigging a gap of about 7/16". Each spark should jump that with a nice hot white spark. If that's OK......<br /><br />I would get a rebuild kit for the carb and tear into it. Soak the carb out good and follow up by shooting carb cleaner through the passages followed up by comprssed air. Don't be afraid to knock out the core plugs and make sure the calibration pockets are clean. Kits come with core plug to replace the ones knocked out.<br /><br />You may also go over the fuel lines and replace any that have become stiff with age and replace them. The "stiffies" tend to lose their grip on connection points.<br /><br />Keep us posted on what ya' find.....thanks.

 

[Timbit]

Re: Need Info on 9.5 johnson

the reason my engine kept quitting was because the fuel line where it hooks to the engine was popping off. i spotted this yesterday when i was trolling. now i have a new problem, the plug in the top cylinder always fouls. the bottom one is burning great. what could be the cause of this???

 

[Paul Moir]

Re: Need Info on 9.5 johnson

I belive on the 9.5hp engine the fuel pump is powered by compression pulses from the top cylinder's crankcase. If your fuel pump diaphram were leaking, that would cause the top cylinder to run rich and fowl out the plug. Try detaching the fuel pump, and pumping up the primer bulb. If any fuel leaks from the port on the back of the pump, you'll need a pump rebuild kit or a new pump.<br />Iboats should have the rebuild kit.<br />Do not disassemble the pump unless you have to. Only remove the two mounting screws.<br /><br />I hope this helps!