2001 115 4 stroke power loss

dudewarner · 06-22-2008, 12:24 PM

Went rockfish fishing today for about 5 hr. lots of moving around, turning motor on and off. Motor ran fine until i was on my way in, it started losing power until the boat a 18' christ craft center console would not plane at full throttle and felt like it was running a little rough so i babied it in. Motor idled fine at the dock maybe a little low on rpms 0.6 and seems like all four cyl. are fireing, died when put in rev. but starts right back up. Never have had any problems with this motor. Has full tank of new gas. Maybe plugs, fuel water seperator, batterys? Any yamaha mecanics out there. Charlie Santa Cruz CA.

DEFIANCE · 06-22-2008, 12:49 PM

Could be lots of things. I'd look hard at the fuel filter on the motor though. Don't know if that motor has 2 or not. Some 4 strokes use a hi and lo pressure filter, and they both need to be changed occasionally.

dudewarner · 06-22-2008, 05:07 PM

Thanks Chris never changed any filters on motor just fuel water seperator. will check my manual tommorow after work.

Carnivore · 06-23-2008, 03:54 PM

Ya that quick I would say fuel related too. Filters, pump, past that I would change plugs then make sure the spark is hot enough by pulling a plug and grounding the boat while cranking the motor. Could be low coil/magneto spark but wouldn't be my first thought. Let us know what you find out.

mochosla · 06-23-2008, 08:28 PM

2001 motor?? Don't they already have the overheat sensor that drops the RPMs to protect the motor? Fuel is definitely a possibility. Check the compression in all pistons to make sure you are okay there.

dudewarner · 06-24-2008, 06:44 PM

Worked on boat after work today and found small amounts of water in small fuel filter on motor cleaned and reinstalled. then went to fuel water seperator - lrg yamaha filter, pulled it and found it was over half full of water with slight rust on top. only 20 30 hrs. Changed plugs and ran ,seems to be ok but have to get in water to really tell. Going to carry a few water sep. and change after first trial to see if there is more water if so i will drain tank. Has been around 102-105 degrees lately where boat was sitting and cool at night. thinking condensation? aluminum tank. THANKS FOR THE INPUT WILL POST AFTER TRIAL / with a fish report hopefully you guys down south with those white sea bass reports are killing me. Never that good here in santa cruz. i am still looking for mine. CHARLIE SANTA CRUZ.

chance · 06-25-2008, 06:45 PM

could also be plugged or partialy plugged exhaust