04 Evinrude 250 DI, Spark plugs shorting out...

[JoePA]

E250FPLSR
04 Rude 250

I just got back from a fishing trip and 2 of the spark plugs on the engine shorted out by a piece of carbon???

Last year I had issues with a bad reed cage gasket went bad so I replaced the reeds and gaskets. Next trip out after that I had one plug short out on me so I just cleaned the plugs and it ran fine for the rest of the week long fishing trip. I replaced the plugs when I got home and then did another week long trip with no issues.

From the last trip to now the plugs only had a few hours on them. I don't troll and keep idle time to a minimum so not sure why the plugs keep doing this. It only started after the new reeds and reed cage gaskets. Any of you ever hear of this happening before? I'll see if I can post some pics the plugs to show you what I mean.

[SEAHORSE]

If the plugs continue to be shorted out by a piece of carbon, that means the motor is running too rich, poor oil quality, or not warming up enough. It may be advisable to remove the heads, clean the injector tips, and clean the combustion chamber, piston crowns, and exhaust ports. Afterwards do a complete decarbonizing of the motor with Evinrude Engine Tuner - 2 cans - and test the cylinder head temp. Better yet, use the QC10WEP plugs, indexed and gapped to .028", and #5005440 thermostats. Make sure the motor is idling about 135°

Evinrude XD-50 or XD-100 lube is best for minimum carbon formation and greatest engine protection.

[JoePA]

Seahorse thank you for the reply. I'm running XD-100 oil as well as running the updated QC10WEP plugs and thermostats. I think I'll pull the heads and do what you recommend. It idles great and runs smooth it just seems this started once I fixed the leaking/broken reed cage gasket. The engine does have close to 700 hours on it so it may be time for a decarb.

[SEAHORSE]

Do not mix up the injectors, they have to stay with their specific cylinders for proper operation

[Bassmeister]

My understanding is if you run the xd-100 you should not have the need to decarb.....Far be it for me to question SH or anyone familiar with the DFI engines.....but I would center my search or resolutions around the reed cages....IE: an engine running xd-100 should not have enough carbon to cause this.....JMHO

[JoePA]

My understanding is if you run the xd-100 you should not have the need to decarb.....Far be it for me to question SH or anyone familiar with the DFI engines.....but I would center my search or resolutions around the reed cages....IE: an engine running xd-100 should not have enough carbon to cause this.....JMHO

I've owned the boat since 2014 and only ran Amsoil in the engine till about 2 years ago when I switched to xd-100. Neither oil should cause carbon build up to cause the problems I've been seeing lately but then again who knows. This engine has been one of my biggest headaches of all the outboards I've owned but by far my favorite!

[SEAHORSE]

Your motor is 15 years old and has not run XD-100 in it for its lifetime. Just like with an old person, starting a good eating and exercising program does not fix what you damaged in your youth.

[JoePA]

Your motor is 15 years old and has not run XD-100 in it for its lifetime. Just like with an old person, starting a good eating and exercising program does not fix what you damaged in your youth.

I agree with you and Mike. That was the point I was trying to make but it didn't come across the way I thought it would.

How much of a pain is it to remove the injectors and disconnect the fuel lines goin to the injectors?

[Bassmeister]

Why not try a decarb first and see if that helps Joe.....I ran a 03 225 HO for 12 years without many problems....now Have the 250 03 model and it's running strong....did have a thermostat cap break and flood engine......replaced the pdp and off to the races again.... Both of my engines I was not afraid to launch and run downstream .....I have never had to be towed.....

[JoePA]

Why not try a decarb first and see if that helps Joe.....I ran a 03 225 HO for 12 years without many problems....now Have the 250 03 model and it's running strong....did have a thermostat cap break and flood engine......replaced the pdp and off to the races again.... Both of my engines I was not afraid to launch and run downstream .....I have never had to be towed.....

I'm goin to try that this week and see if does the trick.

[SEAHORSE]

I'm goin to try that this week and see if does the trick.

Do the decarbonizing two different times using at least a whole can for each procedure. The first loosens and removes the outer and larger carbon deposits and the second effects the loosing of the hardened baked on deposits.

[JoePA]

So, I pulled the plugs last night to see what they looked like after the week long trip. they only had a few hours on them so I figued it would give me a better idea as to what was happening with new plugs and fresh fuel. All the plugs but two have a bright wite spot where its firing, I assume thats good but one of the plugs shows carbon buildup on the grounding electrode the looks like when ice builds up in things when the wind blows. The other it looked like the center electrode was growing to meet the grounding electrode. Eventually it would have shorted out. Is there something more going on with the engine? A grounding problem maybe? Also, all the plug boots and ceramic are very dirty for being new plugs. could the updated QC10WEP plugs be causing the problem?

[SEAHORSE]

Did you also install the E-TEC thermostats, 5005440, and check the cylinder head temps after idling for at least 5 minutes?

[JoePA]

Did you also install the E-TEC thermostats, 5005440, and check the cylinder head temps after idling for at least 5 minutes?

I installed the thermostats but never checked head temps when I did the upgrade

[JoePA]

UPDATE: I thought I posted the fix but it appears I did not. I did the two Decarbs as recommended and during the second one I was checking head temps and noticed one side was cooler than the other. I pulled the Thermostats and noticed that one would not seat properly. I installed another new set of Thermostats, 5005440, as well as plugs and seems to have fixed the problem.

[SEAHORSE]

YEAH !

[Bassmeister]

The Hoss is never wrong.....