2001 Yamaha 200 HP HPDI O2 sensor

2THIRSTY

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Oct 26, 2003
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I have twin 2001 Yamaha 200 HP HPDI with 525+ hours each. The starboard motor will not go over 5000 RPM. The local Yamaha techs say O2 sensor is dirty and asks "Have you been using ring free?". What's Ring Free? And how come nobody told me to use it? I've been reading this (excellent) forum, and I surmize I must shock with ring free, and use ring free and replace the O2 sensor. Of course I will replace the O2 sensor in each motor (wonder how much they cost?). Is this the correct plan of action?
 

rodbolt

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Sep 1, 2003
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20,066
Re: 2001 Yamaha 200 HP HPDI O2 sensor

Hello<br /> the o2 sensores are about 280 apiece I belive. and you really need to find another technician. yours is clueless.the fuel curve map is not affected by the o2 sensor input above 1500 RPM or so. so at 5000 RPM you can toss the o2 sensor in the creek and the motor wont care. test all the filters.have you properly gapped and installed new plugs recently. this motor eats them if you troll between 1200and 1700 rpm.<br /> have you replaced the inline filter between the vapor seperator and the high pressure pump? have you changed or cleaned the filter in the VST tank ? there are some very basic trouble shooting steps to take here. about the ring free. I have some customers that use it at 1 oz to 10 gallons and other customers that refuse to use it at all. out of the 30 or so HPDI motors at our marina the only pair of 200's that I have only had 1 spark issue with is the one that refuses to add ring free.if you have not cleaned the o2 sensor it would be a good idea but it wont help a top end problem. check the air pressure sensor and the air intake senser. also test the high pressure fuel sensor. will be best to hook up the laptop and go boating. that way you can look at all the components that are good so as to save time not testing or replacing good components.<br /> good luck and keep posting
 

rodbolt

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Sep 1, 2003
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Re: 2001 Yamaha 200 HP HPDI O2 sensor

seahorse not on HPDI all othe EFI except HPDI
 

seahorse5

Rear Admiral
Joined
Jan 24, 2002
Messages
4,698
Re: 2001 Yamaha 200 HP HPDI O2 sensor

Now that is an interesting comment about the o2 sensor only working at low speeds. Where did you hear that? I don't recall anything about it in the service manuals, marine tech guide, or at the service clinics. Did I miss something?
 

2THIRSTY

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Oct 26, 2003
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Re: 2001 Yamaha 200 HP HPDI O2 sensor

I will check the various "inline filters". Not sure what VST stands for. I want to mention, when I discovered this problem (I don't actually run above 5000 RPM very often) I noticed that the fuel flow did increase as I pushed the throttle forward even though the RPM did not increase. This would indicate that fuel filters were not clogged. I travel to the Bahamas by boat in the summer time. The fuel in the Bahamas is notorious for water & dirt. I chnage my water separators after every trip and the have been clean - I mean very clean & pure. The idea of hooking up the laptop and running the motor sounds good. How do I get the software & cable?
 

rodbolt

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Sep 1, 2003
Messages
20,066
Re: 2001 Yamaha 200 HP HPDI O2 sensor

hello<br /> seahorse. on the HPDI the o2 sensor is not acted upon at speeds over about 15-1800 rpm. they wanted to avoid the spectacle of a dirty o2 sensor smoking a piston like the other efi had a tendancy to do. its in the fuel systems training manual for yamaha. 2 thirtsy. the VST is a vapor seperator. it is just a mini fuel tank that the medium pressure pump draws fuel from and sends it to the High pressure pump at 50 psi. all it does is insure a clean supply of air bubble free fuel. it is the aluminium tank on the port side up high on the fwd end of the engine. on the bottom of the pump is a fine mesh filter that will clog and cause fuel starving problems. this motor is really not designed for the average backyard do it yourselfer. while it can be done I dont reccomend it. there is another inline filter between the VST and the high pressure pump that should be changed occasionally. its about 137 dollars so stand by. do not use regular clamps and automotive hose to reinstall. this line has 50 to 60 psi of gasoline behind it. you may also wish to rebuild your low pressure mechanical pulse pumps as well.<br /> most of the issues I have with this engine is that its hard on spark plugs. has your been updated to the ngk bkru style double electrode plugs with grey ign coil connectors?<br />there is a tech bulliten on that as well. also check the boat bottom. to often I see motor problems that turn out to be hull issues. thats why I love my IDC 2300 series Dyno or at least a test wheel. allows me to seperate hull/prop issues from engine issues.<br /> good luck and keep posting :)
 

2THIRSTY

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Oct 26, 2003
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Re: 2001 Yamaha 200 HP HPDI O2 sensor

ah.. roger that "backyard mechanic" hint. I am still very interested in the diagnostic software. I used to have Evinrudes (on a different boat) and did get the software. It was very valuable. It lead me to the problem easily. The only thing I actually do on these fuel injected motors is change the plugs. And yes I have the dual pronged plugs with 30 hours on them. But it is the easiest thing to check.
 
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