2005 yamaha 200 hpdi fast idle 1200 to 1600 rpm

mrsbaby1911

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Hello, first thread ever so take it easy on me...lol. Intermittently, my engine will rev to 1200 to 1600rpm. Yesterday, I was able to duplicate this condition on muffs. I suspect the on board fuel tank is the culprit because when I swapped to the small 5 gallon auxiliary tank, the problem disappeared. I need help determining what possible trouble could be with the inboard tank. My research tells me restriction causing lean condition but I can't find this exact problem in any existing thread. 2005 200 hpdi. Z200txrd. 90 model 20cc fish Welcraft. This happens in neutral btw. I also believe I can rule out sticky throttle plates because the problem begins immediately after start up.
 

Capt Ken

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Re: 2005 yamaha 200 hpdi fast idle 1200 to 1600 rpm

Low fuel will not cause a lean condition on a HPDI. If the pressure drops then it quits. Probably due to a faulty temp sensor causing it to stay in the cold start mode.
 

mrsbaby1911

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Re: 2005 yamaha 200 hpdi fast idle 1200 to 1600 rpm

Low fuel will not cause a lean condition on a HPDI. If the pressure drops then it quits. Probably due to a faulty temp sensor causing it to stay in the cold start mode.

Thank you for the reply good sir. I appreciate your insight. Is there a way to diagnose this for certain without computer diagnostic equipment. May I short out the sensor or add a resistor in its place or perhaps open the circuit? If no, then may I ask if the shop has a good chance of determining this sensor even if tech is unable to duplicate failure? I am plagued with intermittent problems on a daily basis in my line of work and am fully aware of how hard they can be to find.
 

Capt Ken

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Re: 2005 yamaha 200 hpdi fast idle 1200 to 1600 rpm

The HPDI can only be checked with the diagnostic system. They did that due to the dangers of dealing with fuel in the 800 psi range.
 

mrsbaby1911

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Re: 2005 yamaha 200 hpdi fast idle 1200 to 1600 rpm

shop gives engine clean bill of health. shop says boat side tank is having a problem but they are unsure of what it could be. I appreciate your insight even though I had to come out of pocket to find out what I suspected to be true in the first place. score one for the shop. shop 1 iboats 0. can anyone help?
 

99yam40

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Re: 2005 yamaha 200 hpdi fast idle 1200 to 1600 rpm

That motor has a vapor separating tank (VST) that the high pressure pump draws fuel out of to feed the injectors.

If the vapor separating tank runs out of fuel due to sucking air from a connection or a restriction in the lines the motor dies. it does not idle high
Did the shop explain how the fuel tank can cause a high idle?
 
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schematic

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Re: 2005 yamaha 200 hpdi fast idle 1200 to 1600 rpm

Have you changed out the fuel in that tank? who knows what witches brew resides in there!
 

mrsbaby1911

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Re: 2005 yamaha 200 hpdi fast idle 1200 to 1600 rpm

Schematic, that is a distinct possibility. I did remove the fuel after purchase but I did not pull the tank and do a thorough job. I used the hole for the sending unit to extract. This does make sense because I removed the fuel I had added after cleaning and placed in aux tank at which point I noticed that the idle did increase, only to 800 rpms but increased nonetheless. I currently have an empty on board tank and would like to hear your advice on proper cleaning if you would be so kind.
 

cpt woody

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Re: 2005 yamaha 200 hpdi fast idle 1200 to 1600 rpm

Few thoughts, have the same motor as you and been through many fuel restriction issues and tank problems with my hpdi. Have not had the problem you discribesd but based on experience think its very unlikely you are dealing with a fuel restriction/tank issue. Would say mostly likely problem is related to what ken said above or problem with one of the other sensors. As you know, in neutral hpdi runs on 4 cyl. When it's cold, my hpdi starts and goes right to 1000rpms and as it warms it drops down to 600rpms. This is one reason I think ken is right and that you motor is misreading actual temp and continuing to run in cold mode.
 

mrsbaby1911

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Re: 2005 yamaha 200 hpdi fast idle 1200 to 1600 rpm

Schematic gets the prize. Turns out that one more flush of the tank and a fresh 30 gallons of Saudi arabias finest, she runs great! I am greatful for all of your input. Thanks to all who replied!
 

99yam40

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Re: 2005 yamaha 200 hpdi fast idle 1200 to 1600 rpm

still does not make any sense how bad fuel would cause high idle on that motor
Think someone was blowing smoke

Timing would have to be advanced to raise the idle RPM or the cylinders that normally drop where not dropping
 
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