New Spark Plugs full of carbon after 30 seconds.

markymarc1 · Jan 27, 2009

I just picked up a motor (1971 Evinrude 6hp), and I am having problems getting it going.

I put new spark plugs in, and have been pulling away at the starter for a few days. It started twice for about 15 seconds over the course of the last few days.

My question is about the carbon on the new spark plugs. I pulled out the plugs while doing compression tests and noticed the bottoms are blackened.

Is this kind of carbon buildup, after essentially 30 seconds of running (and a bunch of empty pulls), indicative of any problems in particular?

I'm hoping to find a clue as to what the next steps I need to take are, so I can get my motor running.

I thought this might be an indicator.

Any thoughts?

Thanks.

tx1961whaler · Jan 27, 2009

Re: New Spark Plugs full of carbon after 30 seconds.

Have you checked for spark with a spark tester?
I see in your other post that the compression is OK.

ezeke · Jan 27, 2009

Re: New Spark Plugs full of carbon after 30 seconds.

Make sure the plugs are J6C Champions set at .030. Personally I would use .040 until you get through de-carbon treatment of the engine or if you plan to do a lot of trolling.

Be sure that the thermostat is functioning properly. Use good fresh 87 0r 89 US Octane gasoline and good grade TC-W3 synthetic or synthetic blend oil at 50:1.

The de-carbon treatment is described in the engine FAQ forum: http://forums.iboats.com/showthread.php?t=158076

markymarc1 · Jan 27, 2009

Re: New Spark Plugs full of carbon after 30 seconds.

Thanks for your replies. I really appreciate the help!

I bought the Champion J6Cs, but didn't check the gaps - just put em' in right out of the box. I'll pick up one of those tools and set it at .40 until I decarb as suggested.

I haven't checked for spark with a spark tester. I assumed (I know that's a bad word) that since I had it running for 15 seconds that I "had" spark.

I'll go pick up a tester too, as (unfortunately) I'll probably cripple myself trying to rig a homemade one. Hopefully they're inexpensive.

tx1961whaler · Jan 27, 2009

Re: New Spark Plugs full of carbon after 30 seconds.

A spark tester is about 8 bucks at the auto part store. If you have an electric drill, chuck up a 3/4" socket in it and use the flywheel bolt to turn the motor over.

BMWboatski · Jan 27, 2009

Re: New Spark Plugs full of carbon after 30 seconds.

Try pouring just a lil bit of gas directly in the cylinder and start it up. If it goes let it run for 30 seconds turn off and repeat. Should be good.

markymarc1 · Jan 27, 2009

Re: New Spark Plugs full of carbon after 30 seconds.

Thanks TxWhaler. The drill will be doing the dirty work in the mean time!

So, I guess the carbon isn't indicative of anything "faulty"?

tx1961whaler · Jan 27, 2009

Re: New Spark Plugs full of carbon after 30 seconds.

I wouldn't think it would indicate anything, until it actually starts and runs awhile. Once you verify that you have spark, then all that's left is the fuel system. There's a screw in the bottom-front of the carb, at the fuel bowl. If you unscrew that, you can at least verify that fuel is getting into the carb. If you have compression, spark, and fuel in the bowl and it doesn't start, then the carb is clogged up and need cleaning.

Rick. · Jan 27, 2009

Re: New Spark Plugs full of carbon after 30 seconds.

I saw the post about using a drill to spin the flywheel and thought I should chime in. It isn't a bad idea, I have done it myself on occasion. The only thing is check your plugs to make sure they are getting wet which will prove your cylinders are getting oil. If not, do the carb. rebuild before you turn it over too often. Rick.

Tim Frank · Jan 28, 2009

Re: New Spark Plugs full of carbon after 30 seconds.

markymarc1 said:
Thanks for your replies. I really appreciate the help!

I bought the Champion J6Cs, but didn't check the gaps - just put em' in right out of the box. I'll pick up one of those tools and set it at .40 until I decarb as suggested.
I haven't checked for spark with a spark tester. I assumed (I know that's a bad word) that since I had it running for 15 seconds that I "had" spark.

I'll go pick up a tester too, as (unfortunately) I'll probably cripple myself trying to rig a homemade one. Hopefully they're inexpensive.

Just to be sure that this was a typo....it is 0.040", not .40".

wbeaton · Jan 28, 2009

Re: New Spark Plugs full of carbon after 30 seconds.

Check the coils. You will have to remove the flywheel as there is no inspection port on it. That's ok since you need to file, clean and set the points to .020" anyway. If the coils are cracked, sweaty or discoloured they are bad even if they spark. Those coils are notorious for going bad with age.

Once you confirm the coils are good and you have good spark, try spraying some pre-mix into the carb and try starting it.

The J6C plugs come pre-gapped at .030". You still need to check them, but I've only ever had to re-gap one new plug.

New Spark Plugs full of carbon after 30 seconds.

Recruit

Vice Admiral

Supreme Mariner

Recruit

Vice Admiral

Seaman

Recruit

Vice Admiral

Captain

Vice Admiral

Commander