115 lacks full speed

[kyleroberts1943@yahoo.com]

I have a problem with a 2001 115 four stroke. I cannot get up to speed. The only way I can get it to go faster is by moving the throttle from wide open to about 75% throttle after I get it to plane off. It will idle and start good. I have changed the fuel pressure regulator. And put new fuel hoses on. It acts like a sensor problem. Have checked the fuel injectors and they appear to be working OK.Once I get it to build a little speed I rotate the throttle and it will get to about 75% of top speed.

[rodbolt17]

does not sound like a sensor issue.
sounds like a rail pressure or injector issue.

[kyleroberts1943@yahoo.com]

Why would moving the throttle from three quarter to full get you more speed if injectors are the problem??? And the fuel pressure is OK. New fuel psi reg. Don"t the injectors get their command from throttle position???

[99yam40]

The only way I can get it to go faster is by moving the throttle from wide open to about 75% throttle after I get it to plane off.

Why would moving the throttle from three quarter to full get you more speed if injectors are the problem?

According to your posts it does not get more speed when moving from 3/4 to full, so why ask that question?

And have you monitored the rail pressure while problem is occurring to make sure it is not dropping?

[kyleroberts1943@yahoo.com]

I have did a fuel pressure test while engine runing. I replaced the psi regulator. When I have the problem the bulb stays hard and it appears it is getting fuel pressure. By slowly moving the throttle from 75% to 100% I got it to plane off. Sounds like Yamaha does not want to help on this forum sometimes.

[rodbolt17]

you have changed your description twice, you say you checked the rail pressure, what was it?

the injector pulse width is determined by lots more than just the TPS.

this site is not run or administered or affiliated with cooperate Yamaha.
I simply don't have a life and waste time.
I am also a Yamaha master technician since 2006.
the first year they offered the test and the 3rd test at Kennesaw.

[bgedwardsfour]

I had the sam problem

I have a 2006 90 fourstroke that had the same problem. Reference the F90TLR post. Check the plugs and see if any of them are showing lean fuel or gray/white on the plug. If so, clean the injectors. It is super easy and there is a video on YouTube for how to remove the injectors. My engine went from not being able to get up on plane to now running at full speed. There is a kit that you can by that comes with the new o-rings and the screen in the end of the injectors if the screen is not cleanable.