2001 Johnson 150 hp has 1 oily, black spark plug

[Johnalcon]

My 2001 carbed 150 hp seems to have one oily and black, slightly carbonned spark plug from the number 6 cylinder. I replaced all 6 plugs 1 month ago and noticed that the plug from the lowest cylinder (number 6 right?) was blacker and carbonned up while all the others seemed normal. I pulled the number 6 plug again today and the new plug is carbonned up (black) while the other 5 are normal to slightly oily. The engine idles fine, starts well and smokes very little. I run xd-50 Evinrude oil in it. However, it runs a bit rough and has a slight vibration in the mid range, 3700-4000 rpm, like it has dropped one or more cylinders. It is not noticable at higher rpm and w.o.t.
I 've examined the plug wires and have spark easily jumping a 7/16" gap on all six wires with no visible weakness in any of them. I changed out the blackened spark plug from number 6 with a spare and it too became blackened and oily. Please help I am stumped.

 

[tashasdaddy]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

check your compression, on all 6 and post the numbers.

 

[Johnalcon]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

I checked compression on my 150 tonight. #1-120, #2-120, #3-120, #4-120, #5-115, #6-105. Something going on in #6?
This is one of the last OMC motors, as I purchased it in late Aug. 2000.
I have it on an 18' Crestliner sportfish, so it has seen plenty of family time with either fishing lines or ski or tube ropes out the back.

 

[ezeke]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

Familiar pattern. Do a thorough decarb, then service your recirculation check valves and pulse limiter.

Decarbon instructions: http://forums.iboats.com/showthread.php?t=158076

# 6 is on the bottom and stuff flows downward in outboards, too.

 

[Johnalcon]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

Thanks for the advice Ezeke. I will do the decarb. How do I service the recirculation check valves and pulse limiter? I noticed that I have a drip of oil hanging from throttle shaft under #6 carb. Is the float level too high or possibly a bad needle & seat? If I pump up the fuel line bulb it does stay hard and I can't see any gas running out of the carb throats.

 

[Johnalcon]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

I did the decarb tonight. What a mess of black yuck that was purged! Mosquitoes are few around here now. I will stick the boat in the lake this weekend to see how it runs.

Anyone know how to service pulse limiter or is it simply to be replaced?

I tested the recirulation check valves by removing the tubing and trying to move air through them with my mouth. One way air passage on all six. Is this an adequate test?

 

[ezeke]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

That will work for the recirculation valves. The pulse limiter should be cleaned and tested as well. It takes a strong burst of air to close the valve.

 

[Johnalcon]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

The pulse limiter was very clean (like new) and closed with about 10-20 psi of compresed air.
On the lake, my motor started easily with very little if any smoke. Sounded normal as ever at the dock.
However, after running it through all rpm ranges, I seem to have an intermittent misfire (or maybe no fire) in one or two cylinders. It vibrates slightly and runs just a bit rough at times between 3200 and 4100rpm. Faster and slower it sounds pretty smooth. I noticed it missed a couple beats during acceleration twice but not the other dozen or more times I acclelerated.
I have checked the coils' primary and secondary windings and all six were within the parameters stated in my Clymer manual. I checKed the plug wires for continuity while I had them off, bending them everywhich way to see if one had a break in it and all were good.
I don't have a "Stevens meter to check the power pack. Is it starting to fail?

 

[ezeke]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

Did the compression change after the de-carb?

Check the throttle linkage between the carburetors; usually section 5 in the Clymer manuals.

Also check for air leaks from the tank to the intake manifold.

 

[Johnalcon]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

Compression did change a little after the decarb, but not for the better. 1-4 stayed the same at 120 psi, while #5 dropped from 115 to 110 psi and #6 dropped from 105 to 100psi. I noticed that #6 spark plug is starting to gain some carbon again after only 2 hours run time.
I gave #6 cyllinder a tablespooon of oil and retested it's compression. It came up 5 to 105psi.
I haven't had time to sync the throttle linkage yet.
There is no obvious air leaks in the fuel delivery but I will keep looking. The tank is built in under the floor and is not easy to get at. Is there a check valve at or in the line from the tank other than the two inside the bulb? The pump bulb stays up all day after the initial pump up so I 'm thinking that it's good.
Thanks for your replies Ezeke and anyone else that would like to help me out.

 

[ezeke]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

I think that you may need to buy new gaskets, pull the cylinder heads and do an inspection.

The cause may be in the carburetors, but the result is the concern now.

 

[GlasV162]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

Your symptoms are similar to what I'm experiencing on my 90 evinrude. A small piece of dirt caused a fuel restriction to one cylinder and now that cylinder locked up. If I were you I'd check for fuel restrictions before running it any more. Good luck.

 

[Johnalcon]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

Thanks for the comments guys. I was gone for the weekend but am anxious to look into my motor problem again now.
Ezeke, I' pull the heads and have a look inside the cylinders. I'll look for scoring. scratches and/or "out of round". Is there away to check the rings at this point? I am certain that the motor has not overheated, as I have owned it since it was new, have never heard the buzzer or seen the hot light come on except prior to starting when it runs its' "check" sequence . I never run it dry and the tell-tale squirter shoots water 10'. It's never been in mud as I only run it on lakes. The entire power head looks brand new (no paint damage).
Glasv162, where exactly was the dirt that blocked one of your carbs? I don't think mine is starving for fuel, but rather might be running too rich in #6, perhaps for quite some time now causing the excessive carbon. Did you get yours unlocked after the cylinder lock-up or have to tear it down?

 

[Johnalcon]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

I pulled the heads and what did I see? Six piston domes covered in carbon expept for 3-5 dime sized areas on each one where the carbon had "let go", probably from the recent decarb. The carbon is about .010" thick. I also saw six cylinder walls that appeared to be showing light scratches in the 30 degree cross-hatch pattern of the original factory honing from 7 years ago. I expected to see polished walls by now, as this motor has 150 or more hours on it (guessing, I have no hour meter). Or is this damage from the crud that was floating around in there during the decarb? There is no ridge at the top of any cylinder above the ring travel, only a light tan ring 1/4" back from the top that the rings don't scrub, where the wear ridge would be.
BUT.....Here's the kicker.... On #6 there is a polished mark 1/8" wide, running paralell to the stroke, the length of the stroke. It is not a scratch or gouge as it has no depth. It is at 9 o'clock as you look into the cylinder at exactly the same place as the top ring gap travels.
Also, there is an area that is the same light tan color as is at the top 1/4" of each cyllinder wall, in #6 cylinder. It is an arc from 9 o'clock (at the polished 1/8" ring gap mark) down to 7 o'clock that is 1/2" wide, 3/4" from the top of the cylinder. Is this ring broke? If it is, wouldn't the discolored area cover more of the length of the stroke on the cylinder wall? I will have to borrow the tools to check to see if the cylinder is "out of round". It appears as if the top ring is not making contact with the wall only in this light tan area. Thanks again for all replies. I'll try to post a picture.

 

[ezeke]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

When I de-carbon, I use a small tank and follow the instructions posted by Capt. Dunkelberger. I do three treatments with a hard run on the water using my main fuel tank between each treatment.

http://forums.iboats.com/showthread.php?t=158076

On my looper I have to switch lines each time. But in the end, I usually have all of the carbon removed by the end of the third treatment.

 

[Johnalcon]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

Here's a couple pictures of what's going on inside my motor. You are looking at #6 and #2,#4#6. The opposite bank is very similar.

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[ezeke]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

I don't see anything there that would worry me except that there is still a lot of carbon.

If you could turn each piston to the top and brush them off and then run another decarb and a test run, you would probably have most of that stuff out of there. I would think that the rings are still backed up with carbon.

BTW, BRP/Evinrude has the decarb on their maintenance chart for once a year.

Go here and click on "Maintenance Schedule" (question 1):

http://www.evinrude.com/en-US/About.Us/FAQ/Maintenance.htm

 

[MikDee]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

Is there a piddle drain on this motor, something that takes away the unburnt fuel, and reburns it, instead of being open to the atmosphere as in the early days (epa required) I know the Force motors have it, and I hear there's problems if they get clogged up, I would think maybe it affects the lowest cylinder, if all the crap goes down, I say this because I have the same symptoms, (lowest plug oily) and haven't checked them yet.

 

[luckyinkentucky]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

I wouldn't worry too much about that last cyclinder. I have a local Evinrude mechanic here tell me that Evinrude does that for a reason. Can't remember why, but mine was 10 below the rest on my last test as well, and he said that was nothing to worry about.

 

[Johnalcon]

Re: 2001 Johnson 150 hp has 1 oily, black spark plug

Thanks for the replies guys. I will put the heads back on tomorrow and get to the lake to do another decarb as per your directions Ezeke. I bought a carb kit to put in #6 carb just to know the needle and seat were up to snuff. Any other thoughts as to why it is carbonning up so much?