fouling plugs on 40 hp Johnson

[tim482]

Hi folks,the problem i am having is fouling plugs on my 40 hp Johnson(TJ40ELESR).This motor is on a 20 ft. pontoon at a no wake lake so low rpm's may be the biggest problem,but there are a lot of other pontoons on the same lake with as big or bigger motors than mine that don't really seem to have a problem.The plugs that i have tried are champion QL77JC4 and NGK BR8HS.I have kitted both carbs, and have it running real good,but after about 8 hrs of run time it gets hard to start hot or cold,so i switch out the plugs and it purrs like a kitten again.Any suggestions on plug numbers ,gap or oil mix(50_1) that might help the situation? thanks Tim

 

[fireman57]

Re: fouling plugs on 40 hp Johnson

Do not run NGK plugs on this engine. You might want to gap the plugs at .40 if you do a lot of slow putting around. Sounds like you want to decarb this engine. Get some seafoam, pull your plugs and dump some in the cylinders and let it sit all night. crank the engine a few times to blow out the carbon. Put your plugs in and the rest of the seafoam in your fuel tank. Watch out because it will smoke like crazy when it starts up. People might even call the fire department it smokes that bad.

 

[mstahl1171]

Re: fouling plugs on 40 hp Johnson

Try out what fireman says...it worked wonders for my 150 Johnny. Another trick you can try if you are low speed for long periods of time is to carry a separate 6 gallon tank with a 40:1 mix. Has worked fine for me when a troll on the bay...but would never run at high speed with that mix...just a thought

 

[tim482]

Re: fouling plugs on 40 hp Johnson

Thanks for the help,i will try your ideas

 

[Rick.]

Re: fouling plugs on 40 hp Johnson

Just to be clear....you mix your fuel @ 50/1 and your not using the oil tank/VRO system? Is your thermostat working properly allowing your engine to get up to operating temp. of about 140F? Not sure about the 40/1 recommendation. To me I would think your plugs would foul even faster at that mix. Best of luck. Rick.

 

[seasprayralph]

Re: fouling plugs on 40 hp Johnson

you might try the champion QL16V plugs which have a surface gap as opposed to the conventional electrodes,, these seem to perform better because there are more areas where the spark can jump