05 yamaha 150 4-stroke 4cyl. running rough

[timster]

05 yamaha 150 four-stroke started running rough and lost power. First off, the batteries are mounted forward in the boat so the battery cables are really long and I think that this may be the problem. We took the boat out one afternoon and we were idling and motor just shut off. Then it wouldn't crank back up, the starter would barely turn over like the batteries were dead. So we unhooked the battery from the front of the boat and moved it closer the motor and hooked back up (eleminating about 15 feet of battery cable) and started up. But now its lost its power and won't run over 4500 rpms or so. I have heard that low battery voltage will mess with these motors. What do you think. Thanks in advance.

 

[timster]

Re: 05 yamaha 150 4-stroke 4cyl. running rough

Now the boat motor won't even crank with new wire going staight from the starter to the brand new battery, so the cranking issue has to be a bad starter. But, im still wondering why it wouldn't run over 4500 rpm after we had the starting issue.

 

[rodbolt]

Re: 05 yamaha 150 4-stroke 4cyl. running rough

starter failures are very very rare and very expensive.
remember thats not a starter like the old jonnyrudes.
its very similar in design to a standard GM PGM starter and needs to be tested correctly,
remember bad ground cables can bit ya too.
first thing is to test the voltage drop along the positive cable then the negative cable.
more than .75V betweem the postive batt post and te start,not batt cable, terminal on the starter means a cable or solinoid issue.
more than .6V between the negative terminal and a good block ground means an issue with that cable.
yes low voltage can and will mess with that engine.
the high pressure pump and the ign system takes 12V. lose it and the systems quit.

 

[timster]

Re: 05 yamaha 150 4-stroke 4cyl. running rough

Thanks rodbolt for the input! We wired up two short battery leads straight to a new battery and still the starter wouldn't even turn over just make a clicking noise. Im betting its the starter solenoid now because the solenoid had red rtv on it so i think someone has messed with it before. but its my buddies boat and he found a new factory starter and solenoid for a good deal so I think that will fix it.

 

[timster]

Re: 05 yamaha 150 4-stroke 4cyl. running rough

Well, we got the new starter on the motor and now it turns over great. But now it doesn't want to start right up, it takes about 10 seconds or more of turning over to start up and now it won't run over 4000 rpm's. We have checked all the throttle cables and everything seems fine. Before it would run 5200-5500 rpms and now its getting worse by the minute. You can pull back the throttle a little and floor it and it will pick up speed for a second or two but then just slowly decrease in rpm. We think its something wrong with the motor or fuel because it wont start right up. Were really scratching are heads now. Any help is greatly appreciated. Thanks

 

[sdsaw]

Re: 05 yamaha 150 4-stroke 4cyl. running rough

-Check thermostat to make sure it is not sticking
-VST (vapor separating tank) service: clean high pressure pump filter in VST
-Get injectors cleaned and checked for proper flow

 

[ram345]

Re: 05 yamaha 150 4-stroke 4cyl. running rough

sdaws is right, the injectors are plugged and need to be serviced , your injection system has 3 filters in it ,not including the recommened water sep filter !

 

[timster]

Re: 05 yamaha 150 4-stroke 4cyl. running rough

Wow, 3 filters I never would have guessed that! Thanks for the input. We will check those things and see what we find.

 

[jblb]

Re: 05 yamaha 150 4-stroke 4cyl. running rough

I have a 2004, 150 with the exact same problem, and was wondering what you found to be the ultimate problem and fix. Thanks for any info. that you can pass along. jblb

 

[fishhardliveeasy]

Re: 05 yamaha 150 4-stroke 4cyl. running rough

its your injectors. 100% you can either send them offf to a place called flagship to get them cleaned and serviced for about $175 a pieace or you can do the old mechanic fix. Take a 9V battery (got to be a 9V) and attach 2 wires with alligator clips one side to the battery and the other to the injector. DO NOT hold the power on the injector to long max about 5 sec. when you do this right you will hear a clicking sound from the injector, that means it is opening and closing. when you get the clicking sound, spray the mess out of it with carb cleaner and you will see the injector spit just like it would gas. when you get a good steady spit your good. When you go to put the injectors back into the fuel rail make sure not to pinch the o rings other wise they will leak. the best way not to pinch them is to hit them with carb cleaner then put them right in. if you cant get the injector to spit the tiny screens are clogged inside and there is nothing you can do. Your starting problem was caused by your injectors and I bet the problem will go away once the injectors are cleaned.