Yamaha 115 running rough - The Hull Truth

flgavilan2002 · 05-17-2009, 07:10 PM

I have a 2001 Yamaha 115 Four Stroke, I went out fishing this morning and everything was running great. After running for like 20 min. my motor started running really rough. The motor was shaking from side to side, for me it felt like it was running in three cylinders. I got home and look at the spark plugs and they where black, so I decided to put new ones on but still doing the same thing. Could it be the Coil or something to do with the fuel (you know that E-10 crap)? I have a water separator and two weeks ago I replaced the fuel filter. Help will be very appreciated. Thanks,

A1 Outboard · 05-18-2009, 07:15 AM

Two things come to mind that could cause this problem. These engines need a combustion chamber cleaner run through them at least once a year more often if you do a lot of low speed running. The valves tend to get cruded up bbecause of the junk gas. The next area to look at is the fuel injectors. Dirty injectors will cause problems like you describe. Several companies offer injector cleaning services to dealers. Cleaning is much cheaper than replacement. Give us a call if you can't find a dealer near you who can have your injectors cleaned.

flgavilan2002 · 05-18-2009, 04:55 PM

Is that cleaner that you are talking about is the one that come in a aerosol can?

A1 Outboard · 05-19-2009, 07:02 AM

Yes, the Bombardier product is stronger than the Yamaha product.

KGP · 05-20-2009, 05:56 AM

Quote:

Originally Posted by flgavilan2002

Is that cleaner that you are talking about is the one that come in a aerosol can?

A better option for cleaning injectors is to have the injectors themselves sent off and professionally cleaned. http://injector-rehab.com/ $16 each with return shipping included.

A1 Outboard · 05-21-2009, 06:06 AM

Cleaning the injectors and cleaning the combustion chamber are two separate operations. Combustion chamber cleaner is sprayed into the intake of the engine when the engine is warm and running. The engine is is shut down and allowed to sit for 4-18 hours and then restarted. After cleaning you may need to change the spark plugs. Fuel injectors can best be cleaned by removing for professional servicing.

davidkuhlmann · 05-21-2009, 07:08 AM

Mercury makes a product called Quickleen that works great on de-carbonizing an outboard. I run it every other tank and have had no carbon issues. I do lots of low speed trolling but in addition to the Quickleen I also run WOT for several minutes on my way back to the launch to help blow things out.