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We are in agreement that they never opened. Pretty sure of this due to sb stat requiring significant manual pressure to force closed. Pretty sure if it had opened it would have stuck open as had been demonstrated numerous times. However, I feel they never opened b/c they never warmed to the required temp. Water was 50 and air temps upper 40's. Both were closed 30 minutes after shutdown (time it took to get to them) but no part of the motor was even remotely warm to the touch by then so one would expect them to be closed. The "faulty" stat would open around 120 but would never close on it's on. Even spent 1 hour in the deep freeze at below zero and it was still wide open.
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Maybe I just need one more sensor...a TSPS. ThermoStat Position Sensor. JK, of course.Comment
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Just thinking out loud now. If anyone is bored with this, please just quit reading and move on. But, this whole situation makes me wonder if there is some design flaw in play here. Motor idles a little rough at initial startup but clears up within a minute or two. I'm told the temperature sensor tells the ECU when to increase rpm (for warmup) and reduce rpm once warmup is achieved. All of this leads me to wonder where this temperature sensor is located and if it is possible to achieve a temp sufficient enough to satisfy the ECM yet once the thermostats have opened allow enough cool water (fresh water lake) to effectively cool the sensor back into a cool start scenario with the motor still running. Seems the sensor could be faulty (out of range) or possibly not in a strategic location on the block. For whatever reason, I believe when the stat sticks open it basically fools the ECU into a "cold start", as Townsend eluded to below:
An open thermostat (especially in water that cold), will cause the ECU to raise the "cold start" idle. The engine is doing what it SHOULD do (on cold start up and NEVER warming up)
It sure seems like this is what is happening.Comment
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Final comment (hopefully) in case there's anyone out there needing to know the outcome. Replaced both thermostats with new OEM and gaskets. Motor runs great at all RPM's now. Occasionally, after warmed, idle is still a tad high for my liking (700-800) but I am pretty sure I can get this to 500-600 range by getting any slop out of throttle cable/linkage and tweaking the TPS one final time after the slop has been rectified.Comment
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Just curious...what is the proper idle RPM for that engine?Comment
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it should be noted that accurate measurement of rpm needs either YDS
or a suitable test tachometer;
the value displayed by the Yamaha 'multifunction tach' digital display
where a single digit indicates 100 -
may easily be 'off' by 1Comment
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Thanks Fairdale, I figured it would be around there.
So HarrisonDawgs why do you want your engine to idle at 500 rpm???? For fishing or something?Comment
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Pana, I guess I was a little premature there as I just got YDIS in the mail yesterday and haven't checked it under running condition yet. To answer your question tho, at 500-600 on my dash gauge the motor sounds good, smooth, doesn't stall and shift is smooth. I notice at times (not always) I get a bounce between 7-8. At 7 the shift is acceptable but if at 8, the shift becomes quite noticeable both in sound and feel. The manual info that comes with YDIS is apparently not specific to my motor (VZ 200 TLRD). The Z200 specs should be the same (or close) but I have yet to find diagrams that completely match my motor. I had read that 650 is optimum but I agree with the 700 +/- 30 as being correct. Replacing the stuck open thermostat has greatly stabilized my idle but I do feel it is still slightly high. At rest, YDIS is showing TPS voltage at 0.63 and T Valve opening at 2.8 degrees. Would really love to know if others think this is acceptable as I cannot seem to get the TPS to consistently bottom at .51 (un-linked). I can set it there fine but once I open and close throttle plates a few times it always comes back to rest at .62-.64. There may be a tad of slop in the cable/linkage that I will attempt to correct.Comment
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I will add this too...I am not completely satisfied with the design of the mounting plate for the TPS. Mine is a metal plate bolted to the block that the TPS is screwed into. I have noticed that the plate has some flex to it. Noticed it first when loosening screws to adjust TPS position. I feel like it flexes enough so that temperature of the block could also contribute to some slight movement. Just seems to me that Yamaha would have designed a mount that would be more sturdy that what I am looking at. Just my 2 cents...Comment
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Also agree with Fairdeal's comment that multifunction tach's can be off by 100rpm. I'm betting YDIS will show the idle around 900 when everything is said and done.Comment
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You need to do a complete link and sink per sm. Tps reading is to high.Comment
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Wondered if you got lost fishing in the snow again? Good to see you are kicking too.Originally posted by walleye1 View PostComment
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Still here, Thank's.Comment
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Walleye, Hi. I've completed the LnS 3 times now, per the book. Problem is that I can set it at .51 resting and after moving throttle plates several times it will never settle back to .51 without physically turning the top throttle plate shaft to fully closed (with pressure). Figured the 3rd time would be the charm after careful cleaning and examination of every component. At this point I am assuming either the springs are not putting enough tension on the return or the potentiometer of the TPS for whatever reason is not wanting to make that last 1/2 degree of rotation at close. Having said that I now have RPMs pretty consistently at 700-800 once warmed and am pretty satisfied. I plan to wait until warmer weather to see if there's any change. At some point I may splurge for a new TPS just to see if it makes any difference. Have even considered adding another return spring (somewhere) to the top butterfly shaft just to see if has any effect. But for now, I'm just going to fish some.
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