2003 yamaha 50 4-stroke runs rough

[Cuppy420]

Starts instantly, idles great and quiet but when I give it gas it boggs down or just struggles and won't put out enough power. Where do i start besides the plugs.

 

[Cuppy420]

Starts instantly, idles great and quiet but when I give it gas it boggs down or just struggles and won't put out enough power. Where do i start besides the plugs.

Sorry...4 stroke

 

[racerone]

There were severe corrosion issues with motors of that era.-----Start with a compression test.----It sounds like a broken record on my part.-----Compression test is quick / easy / cost no $$$ and you learn a lot about health of the motor.

 

[Cuppy420]

There were severe corrosion issues with motors of that era.-----Start with a compression test.----It sounds like a broken record on my part.-----Compression test is quick / easy / cost no $$$ and you learn a lot about health of the motor.

Greeeeat

 

[Cuppy420]

There were severe corrosion issues with motors of that era.-----Start with a compression test.----It sounds like a broken record on my part.-----Compression test is quick / easy / cost no $$$ and you learn a lot about health of the motor.

Are the corrosion issues just with salt water application? That seems to be what I'm reading about but I don't really know. Or is this just that year and model across the board?

 

[Cuppy420]

I will say that the boat hasn't been run since at least June up until yesterday. I hope I'm not in over my head on this one. I know there is a fix for the corrosion issue but parts and labor could cost anywhere from $1000 up to $1500

 

[racerone]

I have a couple of these fresh water motors.----One was declared scrap due to corrosion.-----Also given a 90 HP , declared scrap due to corrosion in water jackets !

 

[Cuppy420]

I have a couple of these fresh water motors.----One was declared scrap due to corrosion.-----Also given a 90 HP , declared scrap due to corrosion in water jackets !

That's not good news

 

[Cuppy420]

It looks like I'm rebuilding the carbs. Everything is leading up to a clogged jet. Even tho it's $400 and a days labor it'll be worth it if it fixes its

 

[racerone]

Do you leave fuel in the carburetors when motor is out or service / boat on the trailer ?

 

[Cuppy420]

Do you leave fuel in the carburetors when motor is out or service / boat on the trailer ?

I just bought the boat. No idea what the previous owner did

 

[Cuppy420]

Finally got the compression test done and it's good but my spark plugs are black af! May very well be one of the problems. Plus I have a fuel leak somewhere and I gotta figure that out

 

[99yam40]

how many of the plugs are black, and if not all of them which ones are black?

sounds like too rich to burn properly, not sure it that could be from spark timing not firing plugs far enough advanced or not.
never seen that before.

make sure the prime start systems are functioning properly.

is there a way to turn them to auto, open, & off,
My C40 has a switch to do that.
if set to the open position that would cause too rich condition.
I see that each carb has a different size main jet, do not mix them up

 

[Cuppy420]

They are all equally black. Not entirely sure what you mean by the prime start systems. Please elaborate. I know I don't have that button it's just a bass boat

 

[99yam40]

YAMAHA OEM PRIME STARTER | 62Y-14380-10-00​

there is one on #1 and #3 carb

they add fuel to the cold motor and should shut off the extra fuel as the motor warms up.
at least that is how the unit on my C40 works