2005 Yamaha 150 Fourstroke Problems

[moose27]

I Have a 2005 Yamaha 150 four stroke outboard on a 21' maycraft. Had no problems at all until December. On first trip out since about august, I noticed boat was not reaching full rpms or speed. Normally rpms will reach 5000 and 45knots. This trip could not get over 3800 rpms or 30knots. motor WILL reach 5000 in neutral. I took boat to yamaha dealer who ran it on dyno machine and said he could not get motor to fail.(said he ran it at 5500 rpms for certain time with no problems) So I took the boat back on the river. At wot boat reaches approx 4800 rpms and slowly drops off to a constant 4100rpms max. the motor sounds fine. can anyone help me?? Prop issues?, Motor issues? any help is greatly appreciated THanks!

 

[rodbolt]

Re: 2005 Yamaha 150 Fourstroke Problems

you have a lot of problems, most start with the selling dealer.
your way overpropped from the factory.
what was fuel system vacum when new/ its on your PDI sheet.
what is it now?
what is fuel rail pressure at the problem RPM?
that motor,once running correctly, needs to be able to turn 5900+ with a normal load.

 

[moose27]

Re: 2005 Yamaha 150 Fourstroke Problems

Im unsure about the fuel system vacum. What exactly is a pdi sheet? Do I have to take the boat somewhere to have the fuel pressure tested? Also, I just took it for granted that the dealer would have the correct prop with the motor. what do you recommend. I do not know anything about prop size, pitch etc. when I take it to the "five star Yamaha service dealer" they tell me nothings wrong. could it be just a prop issue? im baffled. thanks

 

[rodbolt]

Re: 2005 Yamaha 150 Fourstroke Problems

first off never take for granted any shop that relies on a 5 part video course,that can actually be done in 20 min,for technical training.
2nd off never take it to a dealership that did not perform,and have you sign, the Yamaha corperate required PDI sheet(Pre-Delivery Inspection).
google the yamaha website or searh some recent posts for the yamaha dealer locator.
find a shop near you with a master tech or at least a tech that has Fourstroke systems,electrical and fuel systems certifications hanging on the wall.
your description shows a fuel issue, it also shows the hull/engine was most likly never correctly propped.
fuel rail pressure can be checked with a standard fuel rail test guage.
but it must be checked at full throttle and full load.
the injector filters will clog with fuel residue at extended layups, as will the VST filters and the VST pre-filter.
injectors are quite easy to remove, the VST requires the intake manifold to be removed.
takes 1.5 hours to clean the VST and replace the inline filter.