do you see a problem with this plug?

[duff]

just changed my plugs on my 1999 merc 200 EFI and this is what all 6 of the pulgs look like is there a problem with this.

Duff

 

[Chris1956]

Re: do you see a problem with this plug?

Yes, I don't like the pitting. Perhaps the timing is too advanced or the motor is running lean?

 

[8hygro]

Re: do you see a problem with this plug?

Shooting from the hip...It looks rich because of unburned fuel (cylinder wash) and is showing possible piston debris from detonation typical of the low quality fuels today. Possible faulty oiling system or ignition maybee...

The coloring down the insulatior into crimp area is what counts. You would need a proper plug reader or atleast use directed light with a magnifyer to see "into" the insualtor base.

The very low quality pump fuels are creating much havic. Cheap 2-cycle oils add to this.

8hygro

 

[Dukedog]

Re: do you see a problem with this plug?

Lean and tha piston is going away............

 

[duff]

Re: do you see a problem with this plug?

Thank you all for the fast replies,

As for the Pitting, are you talking about the outside of the surface or the inner ring part of the surface near the insulatior?

When you say the piston is going away are you talking it is ready for a rebuild? or did you mean it is going away from the detionation causeing the fuel not to burn (ie timing)?

here are all the pugs. if this helps with the now troubleshooting the problem.

 

[duff]

Re: do you see a problem with this plug?

and the last one

 

[Faztbullet]

Re: do you see a problem with this plug?

If all 6 plugs look this way look for the following: engine to cold at idle, Map sensor hose disconnected,timing retarded or weak stator output(low coil to plug voltage)

 

[LastDollar]

Re: do you see a problem with this plug?

I have an old 1972 1350 Merc. I had the same problem and it was caused by the timing advancing. Merc used a plastic tip on the distributor advance stop and over the years the plastic deformed enough to cause the timing to advance. I lost the top 2 piston to pre-detonation. I was running about three-quarter throttle which had the timing advanced all the way but the carbs where not opened all the way. Caused a lean condition and because the top carb gets the lower fuel pressure it was lean and burned the top 2 pistons. Now as part of the spring check up I check the timing.