18 hp. evinrude fouls bottom plug

[ronnie33]

motor runs fine at w.o.t. but when running slow to troll for fishing it loads up and fouls bottom plug.i had the same problem last year so i put a kit in the carb this spring but that didn't change a thing.

 

[digimortal777]

Re: 18 hp. evinrude fouls bottom plug

what mix are you using , is it the correct heat rating , are you runninb rich??

 

[ronnie33]

Re: 18 hp. evinrude fouls bottom plug

according to a book it says to use 24:1,but a friend told me that with modern oils i could go 50:1.this motor is of early 60's vintage.with fear of ruining the motor,i am using 40:1.i am pretty sure the heat range is correct.ive had this motor for 20 years and have uesd the same type and number every year.it started doing this 3 years ago.i had a reputable mechanic put in new points coil ,etc. at that time but the problem still persists.

 

[fireman 757]

Re: 18 hp. evinrude fouls bottom plug

32 or 40:1 should be okay. Sounds like you might want to check your compression. When you are trolling pull one of the plug wires and see if it arcs to the block. If it does then check the other. You might have a coil breaking down. If you get none or weak spark change that coil.

 

[Dhadley]

Re: 18 hp. evinrude fouls bottom plug

50:1 is fine as long as you use good TCW-3 oil and fresh 87 octane. What plugs are you using?<br /><br />Also on some of those motors in the early 60's the fuel pump is run by number 2 cylinder. The pump may be leaking slightly and fouling that plug.<br /><br />Make sure that when they did the tune up they changed the plug wires. <br /><br />Good luck!

 

[steelespike]

Re: 18 hp. evinrude fouls bottom plug

Ronnie,Dont mess with your oil mix.If it is 16:1<br />Stay with 16:1.Present fuel mix ratios come from improvements In engine technology not oil technology. Your engine is not designed to run on 50:1.It will run for awhile but it wont like it.<br />I accidently ran my 88 50hp.Evinrude on 100:1 for almost a whole season but it cost me $800.

 

[ronnie33]

Re: 18 hp. evinrude fouls bottom plug

compression is 75 on the bottom and 85 on top.not as good as i would like but it should still run evenly.plugs are champion j6c.when i had it running in a barrel the other day,i took the "in" hose off the fuel pump to see how much suction it had.i couldn't feel any,but it keeps the sediment bowl full.it is a evinrude 18hp fastwin.numbers on "freeze plug" are 15032on top and below that are 20533.any more info would be great,but i sure appreciate what you guys have already said,thanks.

 

[ronnie33]

Re: 18 hp. evinrude fouls bottom plug

i was playing with it just a minute ago .i put a screwdriver in each plug wire.the top would only jump about 3/16 inch.the bottom about a 1/16 from the block.i narrowed the plug gaps to .015 inch and now it runs fairly well.does this sound like a coil problem?also, the fuel pump is run off the top cylinder.there is a plate bolted to each cyl.to run the pump off either one.

 

[Dhadley]

Re: 18 hp. evinrude fouls bottom plug

Like I said, make sure they changed the plug wires when they did the tune up. If not, you may want to complete the job now.<br /><br />Good luck!