Carbon, carbon, lots of carbon

Carbon, carbon, lots of carbon

Post by Jim » Thu, 24 Feb 2000 04:00:00


Lots of carbon on my plugs (gaps not fouled yet), pistons look caked in
carbon. How can this be? My Yamaha 225 EFI is only 4 months and 25 hours
old.
Jim P
 
 
 

Carbon, carbon, lots of carbon

Post by Marcus G Be » Thu, 24 Feb 2000 04:00:00

Quote:

> Lots of carbon on my plugs (gaps not fouled yet), pistons look
> caked in carbon. How can this be? My Yamaha 225 EFI is only 4
> months and 25 hours old. Jim P

What does the mechanic where you have it serviced under warranty
say?



 
 
 

Carbon, carbon, lots of carbon

Post by bajama » Thu, 24 Feb 2000 04:00:00

Now THAT is weird!  How does the engine run?  If it seems to have full
power.....I don't know.  It has to be something wrong with the oil injection
or fuel metering or both.  What type of oil are you using?  Please let us
know what you ultimately find out!

Quote:
> Lots of carbon on my plugs (gaps not fouled yet), pistons look caked in
> carbon. How can this be? My Yamaha 225 EFI is only 4 months and 25 hours
> old.
> Jim P


 
 
 

Carbon, carbon, lots of carbon

Post by Jim » Thu, 24 Feb 2000 04:00:00

Well... the boat has been at the yard for three days and "the mechanics are
not recovered from the boat show" ( Miami ). I thought someone on the NG
could tell me the possible problems/causes. I know a lot of people say "it's
under warranty, don't worry about it...". Unfortunatly, I have great concern
I may not see my boat for a long, long while.
Quote:

>What does the mechanic where you have it serviced under warranty
>say?



 
 
 

Carbon, carbon, lots of carbon

Post by Jim » Thu, 24 Feb 2000 04:00:00

The thing runs rough and losses power. I have been using exclusively
Yamalube. It's been in the shop for three days, hopefully  they can get to
it tomorrow.
Jim

Quote:

>Now THAT is weird!  How does the engine run?  If it seems to have full
>power.....I don't know.  It has to be something wrong with the oil
injection
>or fuel metering or both.  What type of oil are you using?  Please let us
>know what you ultimately find out!


>> Lots of carbon on my plugs (gaps not fouled yet), pistons look caked in
>> carbon. How can this be? My Yamaha 225 EFI is only 4 months and 25 hours
>> old.
>> Jim P

 
 
 

Carbon, carbon, lots of carbon

Post by -- Mike - » Thu, 24 Feb 2000 04:00:00

On Thu, 24 Feb 2000 00:48:12 GMT, Dennis Mobley

Quote:

>Jim,

>     What gas are you using? 93 octane?
>     My Yamaha mechanic warned me to us only regular unleaded because
>     high-test gasoline use would lead to carbon build up. He indicated
>     that there was a Yamaha service bulletin on this topic.

>dhm

The last time I was in OMC school, they said regular was all that was
required as far as octane goes... but that most premium gasoline
contains more detergents, which equals a cleaner burn.  

It seems odd that good gas would be bad for  a Yamaha.  Do you by any
chance have that service bulletin?  I wouldn't mind reading it, if you
do, just to see what the specific problem is.

Mike

 
 
 

Carbon, carbon, lots of carbon

Post by Dennis Moble » Fri, 25 Feb 2000 04:00:00

Jim,

     What gas are you using? 93 octane?
     My Yamaha mechanic warned me to us only regular unleaded because
     high-test gasoline use would lead to carbon build up. He indicated
     that there was a Yamaha service bulletin on this topic.

dhm
--
Dennis H Mobley KT4FI
Loxahatchee, Florida USA

Quote:

> Lots of carbon on my plugs (gaps not fouled yet), pistons look caked in
> carbon. How can this be? My Yamaha 225 EFI is only 4 months and 25 hours
> old.
> Jim P

 
 
 

Carbon, carbon, lots of carbon

Post by Jim » Fri, 25 Feb 2000 04:00:00

   No, not 93 octane. I have always put the lower stuff ( 87 octane), but I
have always used Exxon or Amoco...
  Are the service bulletins on the web???
 
 
 

Carbon, carbon, lots of carbon

Post by -- Mike - » Fri, 25 Feb 2000 04:00:00



Quote:
>   No, not 93 octane. I have always put the lower stuff ( 87 octane), but I
>have always used Exxon or Amoco...
>  Are the service bulletins on the web???

I'm not aware of any sites that have them posted.  If there are any,
I'd like to know about them, though.

I just never heard of anyone blaming carbon buildup on using the
better gas.  Bad/sour gas can cause problems, regardless of which
grade it is or what gas station it came from.  

I'd just run the 87 too, but I just don't see why the 93 would cause a
problem.  

It might not be a bad idea to try a different gas station if you
suspect that you are repeatedly getting bad gas.

Mike

 
 
 

Carbon, carbon, lots of carbon

Post by Greg Davi » Fri, 25 Feb 2000 04:00:00

25 hours? What's the break-in period for this motor? Does it
automatically double
the oil used during the break-in period?

Carbon on the plugs could be lots of things but on a new motor you think
you
could assume a few things that it could be but isn't like:
1. Low heat range plugs
2. Burning too rich. Since it's EFI then the computer would have to be
firing
    the injectors for a longer period of time which will make it burn
rich.
3. Weak spark due to coil or wire
4. Running at low rpm for long periods.

First thing I would suspect is burning too rich due to the computer
mucking up.
Don't know all the components of fuel injection on an outboard but in a
car,
the oxygen sensor in the exhaust feedsback to the computer and the
computer
determines from the amount of oxygen in the exhaust, whether the mixture

is right or not and adjust accordingly. Also in autos, the injectors
burn rich
until the engine gets up to temperature then the computer goes into a
"closed loop"
mode where it begins to fire injectors according to exhaust oxygen, load
on the
engine, vacuum at the intake manifold, barometric pressure, temperature
of the
air in the intake.....

So, could be lots of things. Sounds like a job for the shop to figure
out.

 
 
 

Carbon, carbon, lots of carbon

Post by Jim » Sat, 26 Feb 2000 04:00:00

Thanks Mike,
Not sure about the gas station, maybe I'll switch for a while. I guess I'll
just wait for the shop report.
 
 
 

Carbon, carbon, lots of carbon

Post by Jim » Sat, 26 Feb 2000 04:00:00

Greg,
 The break in was 10 hours. I added oil to my fuel tank then at 10 hours the
mechanic checked it out. I topped off the tank after the shop tweak. There
may have been 20-30 gallons of 50:1 gas/Yamalube left in the tank when I
added 100 gallons. I've been told by a friend that the oxygen sensor is
highly sensitive to excesive oil. And... I have been doing a lot of slow
idling lately. Thanks for all the sugestions. I hope the problem can be
easily fixed.
Jim P

 
 
 

Carbon, carbon, lots of carbon

Post by Lloyd Sumpte » Sat, 26 Feb 2000 04:00:00

Quote:

> Greg,
>  The break in was 10 hours. I added oil to my fuel tank then at 10 hours the
> mechanic checked it out. I topped off the tank after the shop tweak. There
> may have been 20-30 gallons of 50:1 gas/Yamalube left in the tank when I
> added 100 gallons. I've been told by a friend that the oxygen sensor is
> highly sensitive to excesive oil. And... I have been doing a lot of slow
> idling lately. Thanks for all the sugestions. I hope the problem can be
> easily fixed.
> Jim P

   Can't remember much about outboards, but in the 2-stroke motorbike I used to
have (Yamaha RD350), the plugs would foul so much they would fail to fire if I
ran it under 4000 rpm for any length of time.

--
"watching broadcast nus /i see th salmon talks will / resume on monday /
well thank god at leest th / salmon ar talking" - Bill Bissett

 
 
 

Carbon, carbon, lots of carbon

Post by Daniel Prokopowic » Sun, 27 Feb 2000 04:00:00

I have heard that synthentic two cycle oil is the cats meow for keeping
two-cycles clean.

--
Daniel Prokopowicz

http://www.nconnect.net/~proko

 
 
 

Carbon, carbon, lots of carbon

Post by Del Cecch » Sun, 27 Feb 2000 04:00:00

Quote:

> I have heard that synthentic two cycle oil is the cats meow for keeping
> two-cycles clean.

> --
> Daniel Prokopowicz

> http://www.nconnect.net/~proko

I have heard that synthetic two cycle oil will wreck your motor.  

del cecchi