Mariner 175 EFI suspicious spark plug?

[reelpro]

I have a 1991 Mariner EFI that was just rebuilt. I have about 10 hours on it with double oil for break-in. I was going to go to the oil injection so I took out the plugs to check them. Five of the pistons had some carbon on them, the sixth one looked a lot cleaner. The plug from that cylinder has some kind of deposit on it. The motor is running fine, starts up good, idles well and has plenty of power.

Here is a link to a picture of the plug.
http://i94.photobucket.com/albums/l115/reelpro/001.jpg

Do I have a problem? I am not going to run it until I am sure what the problem is.

Jeff Nix
Reel Pro Video
Digital Video Productions

[terry taylor]

HI.If it runs well thats great.Iwould clean all plugs shuffle them around while keeping track[mark] run at low speed with double oil still in and read plugs again. just a thought. thanks.

[STVmod]

has this plug been wiped down or is this the way it came out. The reason i ask is if you havent wiped it down, it looks quite dry to me, and i would find out why before you run it again.

if you have wiped it down, i wouldnt be overly concerned, it may be assembly lube residue, depends on what they used assembling the motor, or mabe motor wasent cleened out completly before reassembly. Taylor would have a good suggestion to swap the plug with another hole and run lightly and recheck. if the same residue is there somthing is wrong, if it dosent come back your fine.

Would be a good idea before proceeding further to run acompression check, that could tell you a lot.

[reelpro]

The plug was wiped down. I did a compression check while the engine was cold. It tested 110-112 on all of the cylinders. The part that concerned me was the different look of the plug, and the piston in that cylinder had almost no carbon on it. The other five cylinders had a lot more.