2001 Yamaha 115 rough idle. UPDATE Clemens Marine Response:

TundraIII · 06-01-2009, 01:05 PM

Portside motor is idling rough at low idle since having the motor "de-tuned" at Browns Landing last year. They turned down the fuel and put in hotter plugs to help the motor troll better for long periods.
Thanks, Mike

TNAL · 06-01-2009, 08:28 PM

This sounds exactly like the issue I had w/ my 02 Yami 100HP 4-stroke. Mine was a carb though, and it was carb trouble due to E-10.

Maybe it's a clogged jet at idle? I would really recommend takin it to NW Marine Solutions in Clackamas. I had my issue misdiagnosed twice before they took care of it. Chris is the mechanic out there and hey may be the only certified Yami tech around- he came from North River.

Good luck.

Quote:

Originally Posted by TundraIII

I have a twin set up...starboard motor always runs great. Both motors have their own fuel tanks, separators, batteries, etc. Portside motor runs rough at low idle but runs fine at high RPM's. The motor is idling at about 6 or 700 rpm's (fuel injection). The plugs are fouling quickly (black powdery foul, not wet oil) all four are fouling equally, and they are fouling within an hour or so of use. No water in fuel, no water in oil...oil looks great. I think I'm having an electrical issue but not sure....at low idle the motor dies, which makes it a pain to load on the trailer (did I mention this is a catamaran?). Motor does not smoke. Anyone have similar experience?

Thanks, Mike

TundraIII · 06-02-2009, 02:51 PM

Just found out that the motor is idling too low...she is at 6-700 rpms and she should be closer to 8...motor runs too cold for that.

GorgeCaster · 06-02-2009, 07:12 PM

Check your plugs. Maybe one was fouled with some bad gas, or old gas.

TundraIII · 06-03-2009, 03:42 PM

All four dry fouled at the same time....in under 1hr of operation at low rpm's. Turns out to be a fairly common issue with Yamaha as my research reveals.

TundraIII · 06-09-2009, 07:38 PM

Ok....turned out to be 2 failed injectors...perfect compression...but two dead injectors....and not cheap either...160 each plus next day air...OUCH...but she should be back on the water by Saturday

fishitis · 06-10-2009, 03:05 PM

It's probably too late for you, but I had good luck getting my injectors professionally cleaned by Flagship Marine in Fl. They test them on arrival, clean them, test them again and report the flow rates at two different pressures. About $30 per injector. There are a few other places that do this as well. Luckily, all my injectors met spec after cleaning and I did not have to replace them.

TundraIII · 06-10-2009, 04:09 PM

It keeps getting worse....the shop keeps calling and adding more issues to my basket....now it's just one injector that needs to be replaced and now my "DST" unit needs to be rebuilt because of a bad needle (they say that the unit is "flooding") which is part of the reason the motor idles so badly and loads up. In order to do this they have to remove the intake manifold and risers...blah blah blah. I took it in for a tune up and now I'm at $1200 bucks and I lost my boat for the weekend and into next week. She better purr like a kitten when I get her back.

mookywater · 07-19-2009, 03:53 PM

A second opinion is always best. It may be just me but if they told me one thing then turned around and started adding costs and labor I would yank it before anymore was done and take it to another shop and have them check it. At least I would feel better if I had to spend the money that I knew for sure I wasn't getting ripped off. After all you might be able to get better service and a better deal.