150 HPDI RPM PROBLEMS

[billblaylock]

I have a Z150TXRC that will not cruise between 2000 & 3000 rpm. If I try to stay in that area the motor will either rev up to 3000 or rev down to 2000. The dealer I bought the motor at states that this is how the motor runs and there is nothing they can do. They did change the prop from a 14.5x17 to a 15.25x15 and that only changed that rpm range down 300.<br />I just bought this boat and motor in July & other then that, the boat runs great.<br />I should have ran when the sales manager said "Yamaha gave us a good deal on 10 of these motors"<br />Thank you

 

[bigbrownbuku]

Re: 150 HPDI RPM PROBLEMS

did you have your tps checked? not just the initial setting but the entire range?<br />check for excessive cable slack also.

 

[billblaylock]

Re: 150 HPDI RPM PROBLEMS

Thanks Ben,<br />What is a tps?

 

[shep70057]

Re: 150 HPDI RPM PROBLEMS

throttle position sensor

 

[rodbolt]

Re: 150 HPDI RPM PROBLEMS

it may also be that the boat is falling off plane at that speed. if so it may or may not ever run correctly at 2500. I see heavy boats that do this quite often. as they break plane the motor will speed up due to less hull drag, as they fall off plane the increased hull drag will slow the motor down, a quick session with a test wheel will find if its hull or engine related.

 

[billblaylock]

Re: 150 HPDI RPM PROBLEMS

This motor is on a 19.8ft aluminum Lund Tyee Magnum that weights about 3200lbs with a full tank and gear. I again called the dealer yesterday afternoon and another tech said "the rpm jump is either when the motor goes from 2 cylinder to 4 cylinder or it may be the timing curve. My dad has a 200 HDPI and it has full use of all rpm range. Is this common on a 150 HDPI?

 

[rodbolt]

Re: 150 HPDI RPM PROBLEMS

no but by your techs description find another tech. yours has no clue how the cyl operation works. if he cant describe cyl cut out operation I would find another. like I say a quick session with the test wheel will isolate the hullfrom the motor. if its the motor then the test wheel will also allow futher engine testing. but I would suggest another tech.

 

[bigbrownbuku]

Re: 150 HPDI RPM PROBLEMS

or a run in your boat with a competent tech if no test wheel is available.

 

[billblaylock]

Re: 150 HPDI RPM PROBLEMS

Yea, I think you hit it on the nose with COMPETENT TECH. The Yamaha survey form just came in the mail, they will hear what I think, if it does any good.<br />Thanks for the help from all of you.