2003 yamaha 150 v6-2stroke/ slow mode/rpm problem

hey, i have a problem maybe someone can help. i have a 2003 21ft sailfish( yamaha v6 150) and had it mainteneced couple months ago. we had it mainteneced bc it had been sitting for about a year didnt ride it at all really. anyways after we had it maintenced we had the guy take us out on it bc we are not very familiar with boating. When he took us out on it it rode great , no problems. Then i started takign it out and ever since i started i had a problem. Once i get out onto open waters and try n get on the throttle it wont go fast . i can idle w/o problems at around 2000 rpms btu as soon as i get to around 2500 -3000 the rpms drop automaicatlly then go up automatically. it feels liek it wants to go but just wont. First thought it might be the gas cuz it had been sitting for a year so we used up as much as possible then added a whoel new tank. problem still continued. then added some addivitve and also another fluid to take ethanol out the gas cuz a marine store told me that might be the problem. also cheked the fuel filter n that looked okay. problem still conitnues. I cannot go fast at all and the rpms wont go past 3500 really. it jsut drops up and down by itself. im jsut confused b/c when the guy who fixed my boat took us out it worked fine but now it doesnt and he moved away! do u have any suggestions? please help if u can, very frustrated! thanks chris

Re: 2003 yamaha 150 v6-4stroke/ slow mode/rpm problem

Re: 2003 yamaha 150 v6-4stroke/ slow mode/rpm problem

150 V6 4 stroke Yamaha?
no such animal in existence.
post a model number.
if you dont know what you have we cant help.

Re: 2003 yamaha 150 v6-2stroke/ slow mode/rpm problem

sorry believe it is a 2stroke. the outboard is a 2003 150txr and the boat is a 2003 sailfish-21ft. Hope this helps!

Re: 2003 yamaha 150 v6-2stroke/ slow mode/rpm problem

post the full model number, 150TXR isnt correct for an 03 model.

Re: 2003 yamaha 150 v6-2stroke/ slow mode/rpm problem

Carbs need cleaning or rebuilt,high speed jets are clogged leaning out 1 or 2 cylinders.Or possible fuel tank venting problem,check to see if primer bulb is sucking in flat,if so you have a fuel restriction.

Re: 2003 yamaha 150 v6-2stroke/ slow mode/rpm problem

this first started off about a V6 150 4 stroke,which doesnt exist yet.
then it went to a 2003 150TXR, the problem there is until 2006 the v6 yamahas ran a 4 alpha character suffix behind the horsepower designator.
the prefix before the HP designator will Identify if its oil injected,V max, HPDI,OX66 EFI or VX EFI.
the 150 was made in many many configurations over the years and until we can identify this engine its difficult to say much.

Re: 2003 yamaha 150 v6-2stroke/ slow mode/rpm problem

How difficult is it for you to look at the motor data plate and provide the complete model number? Do you have the owner's manual? The model number should also be in there. Does your motor have a tank for 2 stroke oil?

Re: 2003 yamaha 150 v6-2stroke/ slow mode/rpm problem

Im having the same problem , engine is a 2003 150 hp, 2 stroke, oil injected, v-6. I have a couple of questions, some of them may be amateur questions?


while the boat his running does the primer bulb stay hard or does it become soft?

also the carbs were cleaned by a marina 10/08 and im having the same problem? i tried to sea foam and adding additive to the fuel. the boats runs great for 2-3 minutes and after that my rpms are restricted...

do you think this problem could be relayed to a thermostat sensor?

Thanks for your time

Re: 2003 yamaha 150 v6-2stroke/ slow mode/rpm problem

divers2deep
start a new thread posting your full model number.
in 2003a 2 stroke oil injected v6 150 HP yamaha was avalible in about 7 different models with 3 vastly different ign and fuel control systems.
I lost my magic wand and I am looking at a monitor not a crystal ball.
post a new thread, post a FULL model number and give the exact symptoms,audible alarms and visual alarms on the tach.
details about maint history and when was the last time it ran correctly may help as well

Re: 2003 yamaha 150 v6-2stroke/ slow mode/rpm problem

Rod bolt if you have a look at the original thread it does actually say 150 v6 2 stroke not 4 stroke like you say so it did start off with the correct title. You sound like you know what your talking about with these engines so why can,t you use your knowledge and give the guy some advise shawley you must have some idea on where to start. sounds to me like a restriction in the carbs or a fuel problem somewhere i would start with the carbs off and go through them.

Re: 2003 yamaha 150 v6-2stroke/ slow mode/rpm problem

QSS
about all I can tell you about a 2 stroke V6 Yamaha in 2003 was it was painted silver blue metallic.
after that I can tell you it was based on a 2.6L block.
after that all bets are off as several models in the 2003 150 lineup had carbs, EFI did not and neither did the 150 HPDI.
so when you can ID the engine we are disscussing then yes I can give reasonable answers.
wont help my spelling or keyboard skills but then I can discuss what may be happening.
between 02 and 03 there was an L150,s150,D150,P150,DX150,PX150,LX150,sx150,VX150,Z150,LZ150,VZ150.
which ones had carbs,EFI or HPDI?
you identify them by the model numbers.
so you see I am not trying to be sarchastic and yes some folks think I may know what I am doing.
Yamaha says I met the criteria for their master technician program and actually gave me a certificate.
but I cant tell him to go look at his carbs as he may not have them.
I cant tell him to hook up a laptop because unless its HPDI it cannot be accessed with a laptop.
I cant tell him to look at fuel rail pressure cause EFI is 35PSI and HPDI is 50 psi.
if the regulator sticks open or shut either situation could occur. to much pressure on the 35PSI EFI system will cause a very rich burn, 35PSI on the 50PSI HPDI system may lead to low high pressure fuel rail pressure and will lead to lean running.
so ya see, until its identified there really isnt much I can do without my magic wand or my crystal ball.
all I need is enough information to identify the ign and fuel system being disscussed. without it its like saying how high is up or how dark is black.

Re: 2003 yamaha 150 v6-2stroke/ slow mode/rpm problem

at the end of the day master tech rod bolt couldn,t you offer some advise like "if you have a carb engine try this........... etc...." after all this forum is to help is it not?

Re: 2003 yamaha 150 v6-2stroke/ slow mode/rpm problem

Plug a portable gas tank into the engine. Fill with fresh clean gas. Take the boat out for a run on the portable tank. If the problem goes away the problem is in your boats fuel system( plugged pick up, plugged vent, kinked hose, filter...etc.) If problem is still happening then you know to start looking into the engine for the problem. You will want to get a primer bulb an hook it up between the portable tank and the engine 5/16 or 3/8 fuel line will work. And bring some extra fuel with you it don't take long to burn through 6-12 gal. on a test run some times. The problem might not even be fuel related this is just a simple test that might help narrow down some variables

Re: 2003 yamaha 150 v6-2stroke/ slow mode/rpm problem

QSS
nope, I can only help those that help me and the rest.
if no one can ID the fuel,ign system being disscussed why disscuss it.
if its a fuel restriction and you attempt to run 6-12 gallons through it its very possible to smoke a piston or toss a rod.
HPDI and Carbed motors inject the oil in the intake bypassing fuel systems.
EFI mixs oil and gas in the VST and each of the 6 injectors spray this fuel oil mix into the intake.
lose an injector or rail pressure and now we have way to much air,not enough fuel/oil and possibly now a very lean air/fuel mix that can wipe a piston or burn a rod bearing.
I am a technician not a magician so I try not to make guess's.
its why its so imperative for a technician to understand what he/she is working on and how it works and what each subsystem does to the complete subsystem.
here is a quick test,call napa,tell them you want an altenator for a 2003 chevrolet V8 and give them NO other information. see how many questions get asked but still refuse anyother information about that chevy. see how many choices they give you.

Re: 2003 yamaha 150 v6-2stroke/ slow mode/rpm problem

yeah riiiiiight, you bet sheriff.