Fouling plugs.

[fishon!sc]

I have a 09 Merc 50 2 stroke. In the past week it has fouled the plugs twice. Both times it was just one plug out of three. I will be riding along fine and bam it starts running like carp. Change the plugs and it runs fine again. The only thing that was changed is I added sta-bil to the gas last week. It was the blue kind and it was new gas. Any ideas what could be fouling the plugs? This motor is barely a yr old. Thanks for any help.

 

[fishon!sc]

Re: Fouling plugs.

Bump.

 

[fishon!sc]

Re: Fouling plugs.

Anyone?

 

[robert graham]

Re: Fouling plugs.

The wrong spark plugs(different heat range), old or contaminated gas, way too much oil in the mix, very rich fuel mixture caused by faulty carbs, injectors,thermostat(making it run rich), any of these could foul plugs. Good Luck!

 

[sschefer]

Re: Fouling plugs.

I have a 09 Merc 50 2 stroke. In the past week it has fouled the plugs twice. Both times it was just one plug out of three. I will be riding along fine and bam it starts running like carp. Change the plugs and it runs fine again. The only thing that was changed is I added sta-bil to the gas last week. It was the blue kind and it was new gas. Any ideas what could be fouling the plugs? This motor is barely a yr old. Thanks for any help.

Is it the same plug each time or does it move around?

 

[fishon!sc]

Re: Fouling plugs.

Yes. The #2 plug.

 

[sschefer]

Re: Fouling plugs.

Could simply be a bad plug wire or a coil failing. Swap the plug wire with another one and see if it moves to the other cylinder. There is a chance that when you move it, the problem may go way and it was just poorly seated in the coil or there was some minor corrosion going and the move cleared it.

Let us know the results and we'll take you to the next step.

 

[fishon!sc]

Re: Fouling plugs.

Thanks for the help. I will give it a try and let you know. I run synthetic 2 stroke oil. A guy at work told me the smaller hp motors have problems burning it off and will foul the plugs. Never heard of that. Said his 25 hp was fouling plugs. So he quit using the synthetic oil and it quit fouling plugs.

 

[sschefer]

Re: Fouling plugs.

That's always a possibility. These motors are very loosely designed to cover a broad range of uses. With that in mind, there is every opportunity for individual motors in a production line to run and act a little differently. For the most part they don't but the one thing the engineers can't control is break in and maintenance. Those two factors can end up making two identical motors have different operating charateristics. Generally speaking the near smokeless synthetics should burn cleaner but in your engine they may not.

 

[fishon!sc]

Re: Fouling plugs.

Thanks alot for the help. I do not know alot about 2 stroke outboarbs but I have worked on my share of 2 stroke dirt bikes. I would think they would be somewhat alike. The thing that I do not get is the plug does not looked fouled. All three are a golden browen, it will run like crap until I change the 2 plug. Then it runs great.

 

[sschefer]

Re: Fouling plugs.

Thanks alot for the help. I do not know alot about 2 stroke outboarbs but I have worked on my share of 2 stroke dirt bikes. I would think they would be somewhat alike. The thing that I do not get is the plug does not looked fouled. All three are a golden browen, it will run like crap until I change the 2 plug. Then it runs great.

That's bizzare. I wonder if its heat related and the time it takes you to change a plug is long enough for it to cool. Get yourself a hair dryer and heat up the various igniton components and see if you can induce the problem.

 

[fishon!sc]

Re: Fouling plugs.

Well I put new plugs in. Changed the wires around and put new oil and gas in it. I rode around for about 4 hrs and I never fouled a plug. Now a problem I had in the spring is back. It runs rough from idle to 2000 rpms. Above 2000 and it runs fine. At idle the motor is really bucking around. If you are running at 2000 rpm it will drop down to 1600 to 1800. It might come back up to 2000 are it might not. When it did it the fisrt time in the spring the dealer said the blub was bad and changed it. I did not think they fixed it but they said the motor is fine. Now it is getting worse. Any ideas. Plus this motor might have 25 hrs on it. I am about ready to get rid of it. I got new so I would not have to worry about. My 20 yr old Johnson runs better this this motor. Thanks for the help.

 

[sschefer]

Re: Fouling plugs.

Typically, that's a pretty good indication of a stator problem if we couple it with the fouled plug but... it's an expensive fix and I tried not to lead you into it right off the bat. It would be a good time now diagnose it.

Do you have a DVA and Multimeter? The cost is equivelant of the shop time required for the test. Unless you have a desire to get into these motors in depth, you probably won't use a DVA for anything else and I recommend having a shop test it.

 

[fishon!sc]

Re: Fouling plugs.

I would like to do it myself. Do not trust dealers. Want makes me mad is the warranty run out 2 weeks ago.

 

[sschefer]

Re: Fouling plugs.

I would like to do it myself. Do not trust dealers. Want makes me mad is the warranty run out 2 weeks ago.

O.K. Go get yourself a Merc Service Manual first.. Not the Seloc or Clymer, the real deal.

Try using the catalog feature at www.crowleymarine.com to locate the correct manual for your motor then order it.

Then go over to www.cdielectronics.com and download the ignition/charging systems trouble shooting guide for your engine.

Do a search on DVA's here there are a couple of guides for making your own or you can buy one.

Mulitimeters don't have to be fancy but they need to cover the resistance and voltage ranges that you'll find in the CDI and Service Manual guides. I have an expensive Fluke digital but for these tests, I prefer my old analog.

That will get you started... Still want to move forward with this? Are you thinking it might be worth hauling the boat out of town to a different dealer?

 

[fishon!sc]

Re: Fouling plugs.

I want to tell you thanks alot for the help. I already have the merc manual, but you know what mercury sould have to fix it. So I called mercury and they are going to fix it. They have a record of already working on it. Give me a guy to call. It is going in the shop next Tuesday. I will let you know what he finds. Thanks again

 

[sschefer]

Re: Fouling plugs.

There ya go... smart man..

 

[fishon!sc]

Re: Fouling plugs.

Update. So far he has found a bad coil and fuel pump. He said since merc is paying he going thru the motor with a fine tooth comb. I feel alot better. Thanks again for the help.

 

[lncoop]

Re: Fouling plugs.

Update. So far he has found a bad coil and fuel pump. He said since merc is paying he going thru the motor with a fine tooth comb. I feel alot better. Thanks again for the help.

Outstanding. You did exactly what I was about to suggest had I not read on. Good for Merc.

 

[fishon!sc]

Re: Fouling plugs.

Well I got her back and she runs great. I am very happy now. I even picked up 3 mph. Thanks for the help.