High speed glazing

[StAugJonboat]

96 mercury gamefisher 5hp 2 stroke, plug is glazing after about 30 minutes drive causing misfire... how can I remedy this?

 

[GA_Boater]

Glazing? Not sure what you mean. Black and sooty?

 

[StAugJonboat]

No. I was reading up on it, "Insulator has yellowish glazed appearance. Indicates that combustion chamber temperatures have risen suddenly during hard acceleration. Normal deposits melt to form a conductive coating. Causes misfiring at high speeds." www.gsparkplug.com. it says to use a "colder" plug...

 

[racerone]

This is interesting.----Post the results after new plugs and some testing.

 

[StAugJonboat]

I've run it with a new plug... runs great for 30 minutes then starts misfiring again. I'm going to adjust the fuel mixture then replace the impeller... thing maybe it's running hot causing the plug problem...

 

[jimmbo]

How old is the gas? And, what additives have been added to it?

 

[StAugJonboat]

It isn't too old, it's been filled twice in the last 2 months... 3 gallon tank. The 2 cycle I use has fuel stabilizer in it, no other additives

 

[StAugJonboat]

Checked impeller, it's fine. Water tube is clear, its peeing ok..
kind of at a loss..
might need to change fuel mixture maybe? Any suggestions?

 

[Scott Danforth]

you realize that 2 cycle oil is a stabilizer by itself. skip the fuel stabilizer and run with good clean fuel.

 

[gm280]

Post some picture of the plugs. I'd like to see both the electrodes and the ceramic insulators.

 

[dingbat]

What plug are you running?

like to see a picture.

Combustion temps are a product of fuel and air mixture in a 2 stroke. A “glazed” plug viewed from a 2 stroke perspective is a lean condition.

 

[StAugJonboat]

I'm running the recommended plugs. I ran the boat the other night after cleaning the plug with brake cleaner, it ran like crap for about 10 minutes then smoothed out. I'll try to get pictures of the plug in the next day or two. I work nights in the ER... doing a 3 day stretch right now.

 

[Scott Danforth]

I work nights in the ER... doing a 3 day stretch right now.

shouldnt you be attending people vs being on iboats.

 

[StAugJonboat]

shouldnt you be attending people vs being on iboats.

I go back to work at 7 tonight

 

[dingbat]

I'm running the recommended plugs.

According to the manual you should be running a L87YC plug.

Subsitutes usually don’t work out well

 

[StAugJonboat]

I've got a model number 587506... maybe this site has the wrong info...

 

[dingbat]

I've got a model number 587506... maybe this site has the wrong info...

same model numbers...hummm

https://www.perfprotech.com/mercury-marine-parts-catalog/cylinder-block/assembly/2324/7?model=1507

 

[StAugJonboat]

Crowley marine shows the same plug you do... maybe I'll give that a try

 

[StAugJonboat]

So here's a plug a pulled out a few weeks ago. Probably run fire about 2 hours, cleaned with seafoam and than for another hour.. forgot I had done that... hence the little bit of rust forming... next is the new plug, came in the mail today. All this being said, where fishing there let day, ran the boat twice, high speed misfire isn't happening, but it is at mid throttle now

 

[gm280]

So here's a plug a pulled out a few weeks ago. Probably run fire about 2 hours, cleaned with seafoam and than for another hour.. forgot I had done that... hence the little bit of rust forming... next is the new plug, came in the mail today. All this being said, where fishing there let day, ran the boat twice, high speed misfire isn't happening, but it is at mid throttle now

The two plugs you show are not the same. One (newer looking one) looks like a long reach, while the used one is short. I hope there was not issues with piston hits. IDK.