yamaha 115 acceleration problem

[striderboat]

Just put boat in water after winter. Ran well for about ten minutes then purposely slowed down to 8-10 mph for 15 minutes (no wake zone). When tried to accelerate engine would run good up until about 3500 rpm's after that the engine would not accelerate and would slow down when increasing throttle. Runs fine at low rpms. Tried the next night same problem rpms increased to about 4200, if the throttle is increased the engine would slow down tojust under 4000 rpms and the rpms would go up and down about 400 rpms.

115 Yamaha 4-stroke 2002 (330 hours)
Prior to winter mechanic winterized boat, replaced thermostat, fuel filter, etc and used valve-tec decarbon. showed codes for eng to cold and shift switch.

Had to recharge batteries prior to putting in water. They may not be fully charged.

Mechanic said I should run the boat to see if it cleans itself out, any thoughts?

 

[Casco Bay Outrage]

Re: yamaha 115 acceleration problem

Was the fuel fresh or last year's? If last years, was it treated? Do you have a water separator filter?

Sounds like bad gas and/or clogged fuel system, i.e. VST, injectors. There are several active threads. Do a search on F115 and VST.

 

[striderboat]

Re: yamaha 115 acceleration problem

Filled it up before winter, gas was treated, there is a water seperator filter
Thanks wil do a search

 

[cousinabe]

Re: yamaha 115 acceleration problem

http://forums.iboats.com/showthread.php?t=299466

 

[striderboat]

Re: yamaha 115 acceleration problem

Thanks for the info, the problems seem very similar. Took the boat out a couple of times this weekend and the performance is improving. Originally I could only get a steady 3,500 rpms WOT would bog down rpms would decrease. last time out could get steady 4800 rpms would still bog down with wot. Max speed about 28 mph two years ago it was running at 40 mph, last year max speed was about 35 mph.

Based on the old threads what is the estimated cost to have mechanic repair, filters and send out fuel injectors ?

 

[Casco Bay Outrage]

Re: yamaha 115 acceleration problem

$400-$600

 

[striderboat]

Re: yamaha 115 acceleration problem

Just dropped the boat off at the shop. Technician checked the fuel pressure and said it was good, everything that was visible looked good.

Is suggesting that I have the VST filter replaced and the injectors sent out for cleaning. His rough estimate on cost $750, you mentioned $400-$600 and he stated that he could not gurantee that this would solve the problem. Based on the symtoms he believes it will.

Any thoughts.

 

[striderboat]

Re: yamaha 115 acceleration problem

Just got boat back from the shop, replaced the vst filter and sent the injectors out for cleaning cost $850. Viewed the old VST filter it had some small particles.

Boat is running great, hope it continues. I believe the bill is high but my options were limited. Thanks for the help