yamaha no power

I have a 2003 115 4 stroke that ran great. Couple weeks ago it started going up and down 9n the rpm.now it want get above 2500 rpm at best. I have bypassed water seperator and changed the plugs but nothing.if I pull out the warmup lever it will hit 6000 tons.could 5his still be a feul problem thanks for any help

Re: yamaha no power

sorry about the spelling in the first post, I was on the lake and using my cell phone. I wanted to add that I put the motor in reverse and it seemed fine. The motor only boggs when in forward gear.

Re: yamaha no power

check the shift position switch, also check the rail pressure.
usually bypassing the water seperator leads to instant VST filter clogging.
most likly time to remove the VST and change the filter.

Re: yamaha no power

ok, thanks rodbolt. I put the fuel separator back on,i checked the oil and it was full of gas and way!!! over full. I drained and replaced and also changed oil filter. I never run this boat more than half throttle and almost always under a load with 3 or 4 guys and bait tank and all that stuff. we usually fish at night dont go far. I have been watching the oil and noticed it is rising, will the oil level being to high cause one to bog down? the shift position switch makes sence because sometimes it quits when shifting from forward or reverse back to neutral, how do you adjust or check this switch. also forgot to mention once i was going down the lake before all this started and i hit the trim button and the motor cut off completely,

Re: yamaha no power

if hitting the trim shuts down the engine carefully check your battery cables for corrosion and tightness.
reattaching the seperator wont help if the VST is already contaminated.
VST filter maint is routine every 200 hours OR 1 year whichever occurs FIRST.
many things can lead to EFI engines making oil,leaking VST needle valve,stuck open Tstat and over propping are the leading causes.

Re: yamaha no power

just thought i would post follow up, it might help somebody. I changed oil and filter and took to lake, ran better but still wouldnt get above 3500 rpms and then it would gradually start to bog. so today i take the vst tank off anf this thing was full of trash and my fuel pump looked like it had little black specs stuck to it. the filter was completely clogged. i cleaned everything with carb cleaner and put back together. I took it back out and it ran terrific. I still couldn,t get above 5000 rpms but i think this is because someone sprayed the bottom of the boat(carolina skiff 238v) with what looks like spray in bed liner, It feels like sandpaper. I guess my next project is to sand that stuff off and wax the bottom up. thanks rodbolt for your help on this.bythe way it is a 17 prop