Water temperature sensor assembly different part numbers?

Blrfl

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I get all that thanks. I think it's interesting that Honda redesigned this part in the "08" redesign.
They may not have had any choice. The throttle bodies and ECM are OEM'd from Keihin. The ECM changed in 2008, so it's always possible that the old ECM they were using was discontinued or the new version let Honda improve emissions so they could manufacture the ST longer. That's all speculation, though.

... perhaps the onboard computer is not so freaking fussy about all of it, dumping extra fuel at the drop of a hat or a couple of degrees.
I don't think it's a case of the computer being fussy. I'd bet that there's enough hysteresis in the system that if the engine has reached operating temperature once, small changes aren't going to convince it that it needs to warm up again. The cooling system in this bike is brutally efficient, and if there's coolant flowing and wind at the radiator, the engine temperature is going to drop. A lot. The ECM has no way of knowing the cause; it just knows the engine's not warm enough and something has to be done about it. If a sensor fails outright or is giving readings that are impossible (such as a coolant temperature of 50 degrees when the air temperature is 80), the ECM can punt and use sane default values that will keep the engine running, but not in an ideal way.

Anyway, the bottom line is that if your fuel economy is ratty, there's probably a reason that can (and should) be corrected.

--Mark
 
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JimGregory
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Anyway, the bottom line is that if your fuel economy is ratty, there's probably a reason that can (and should) be corrected.

--Mark
Yep. Just waiting on time weather and parts. First things for ya know.
 

wjbertrand

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I have a bunch of used sensors, coolant temp, o2, crank & cam position, tip over... used but apparently good as replacing them did not solve my misfire issue. I'll sell them cheap.


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JimGregory
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To close this out, Did a throttle body sync as well as the new new thermostat and all is well and smooth.
Coolant temp sensor plug appears fine.
The end!
 
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I know that this is an older thread, but felt this where my query should be posted. I had a couple of issues under the tank to sort out this spring and the engine wasn't warming up as it usually did. Also on a couple of occasions, the temp gauge was showing overtemp and flashing the last bar. So I lined up some parts including the tstat, a new temp sensor, and a couple of rad hoses that I knew need replacing. Even though the engine didn't appear to over heating and the fans were cycling on/off as normal, I did the changes of all the parts. The engine is now warming up more quickly, but on several occasions and even with a cold engine at start, I have had the temperature display flashing the 'overheat' indication. New sending unit faulty or poor ground on the t'stat body?? Does any one have the specs, cold and hot resistance for this unit? Any help would be appreciated. Thanks Ed
 

dduelin

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As ST1300s age we are seeing more ground issues and this is a simple thing to check and/or repair. Fabricate a new thermostat housing ground with two ring terminals and a length of AWG 16 gauge to a known good ground - like under one of the bolts threaded into the frame that retains one of the ignition coils.
 
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Thanks Dave and Larry for your responses. I have to find some time to get the tupperware off again. I was thinking about the way they ground the t'stat housing and thinking that could be a problem. I had checked the wire when I had everything apart and it checked out ok at that time. However intermittent problems like this are the hardest to find. Again thanks.. Ed
 
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Get a 12v tester, and use it not only to make sure points that should be hot relative to ground really are hot, but also to make sure that points that should be ground relative to +12v really are ground.

1601614534797.png
 

ST Gui

240Robert
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Al st1100 said:
Digital test lights are cheap and come in real handy.
Hey that looks to be a nice bit of kit! The two most useful functions of a DMM in one simple to use tool. My Fluke and HF DMMs will be jealous.
 
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This is like the one I actually have. (The above pic was from a fast find.) All it has is a red/green LED polarity indication.

I can do all the roadside troubleshooting I might need to do with it. If I need to know actual voltage, I use a voltmeter.

1601622474915.png
 
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