2000 yamaha 115 4 stroke idles at 4500 rpms

cnorris42

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Jul 20, 2015
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after finding water in fuel cleaned fuel system,cleaned vst and found I had a bad high pressure pump ,replaced it.put it all back together and now it idles at 4000 t0 4500 rpms . boat ran fine before water got in fuel. I can't find any info on this problem. please help.
 

99yam40

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I am fairly sure you did something to make this change , but no idea what that was as I was not there
 

schematic

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make sure the all throttle valves are adjusted correctly and not hanging up. an intake leak can also cause this. are all orings in place?
 

cnorris42

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I will check the intake and look at all I did to see if I see something I put back wrong . Thanks for your help , I will let you know what I find. the o rings are ok ,could the metal intake gasket have the wrong side to the block or can it go either way?
 
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cnorris42

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Jul 20, 2015
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after tacking intake and pump off checking everything ,I put it all back together ,now it idles at 2000 going up to 3500 back and forth could this be the injectors?
 

cnorris42

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well I went back and looked over motor and I had left a hose off the intake silencer now same thing cranks and idles at 5000 rpms. if anyone has any ideas please let me know. in bad health and would like to take my wife and grandson out for a ride soon.
 

tommarvin

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I understand, I can't tell you how many times I have worked on my motor and it wouldn't run or it was worse.
It worked before you worked on it, you were just trying to do the right thing, I would install a 10 micron spin on water separating filter, above deck on fuel side of motor, on transom. Stops all water and bad stuff.
I would get a factory service manual, so you have something to go off of.
Then go back and check everything you did to the motor, you will find it.
 

99yam40

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IMHO the throttle plates must be open too much at idle to have RPM that high,
has to be getting air along with fuel

These newer motors have all sorts of sensors and an ECU to control things.
need to take it to someone that understands the controls and has the proper test equipment.

let us know what you come up with once the problem has been solved, it will help someone else down the road I am sure
 

cnorris42

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Jul 20, 2015
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I will get a water separator, thanks. and I am still looking at everything I have done , something must be telling it to open up because the throttle body looks good before I crank it checked all vacuum lines gaskets linkage . ill take it off and look again it only takes me about 20 min, ,I ve done it so many times. if I ever find out I will let everyone know. Thanks Randall
 

cnorris42

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Jul 20, 2015
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I got a service manual and a real mechanic coming soon, Thanks for all the help , I will post when we find out somthing
 
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cnorris42

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Jul 20, 2015
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mechanic never showed up , I cant find anything loose or wrong on what I did so I am going to park it until I sell something . so I can take it to a dealer . thanks for the help
 

tommarvin

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Nov 22, 2015
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Try to pay for a half hour diagnosis,from a certified Yamaha outboard mechanic call till you find them, then you fix it and buy any parts.
 

tommarvin

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Nov 22, 2015
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You crossed my mind today, one of our carb butteryflies was open a little ,when the remote was in neutral.and wouldn't idle down. Check butterflies are 100% closed if you have carbs. Did you do any throttle adjustments., Check for a vacuum leak like schematic mentioned above.
If I were you I would go over to your motor and take everything apart that you touched or worked on inspect everything very carefully, and put everything back together. Make a list of everything you touched/worked on, you can fix this, don't give up.
 
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