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1Back to top Go down    Can Water Temperature Sensor be Bad?????? on Fri Mar 16, 2018 11:43 pm


active member
active member
My 89 K100RS hasbeen ina no start, poor enrich running condition. Upon cleaning up the water temperature sensor, the engine now isin a hardstarting conditionand the engine runs poorly in an enrich running position.

My questionare these:

Can the water temperature sensorstart going bad but still allow the engine to be started? Can a bad water temperature sensor cause a poor, enrich running, engine?When I disconnect the water temperature sensor harness while the engine is running the engine straiten up andruns like it should. I do not really understand the relationship of the temperature sensor to the Fuel Injection Control Module except that it passes a ground to Pin #10 on the Fuel InjectionControl Module. Can I have a good water temperature sensor and a bad a Fuel Injection Control Module? The engine will not start if the sensor wiring harness is disconnected from sensor.

I attempted to ohm the sensor but did not understand the ohm results. I have a new sensor on order but I am wondering if I can have other problems causing my hard starting,poor, enrich runningengine on my K100RS.

Any comments, suggestions, advice or recommendations are welcome and appreciated.

Bill Hutchens
San Antonio, Texas


RicK G

RicK G
Yes it surely can. I have seen it on many cars and bikes. They don't actually stop but just give the ECU bad info.

"Every normal man must be tempted, at times, to spit upon his hands, hoist the black flag, and begin slitting throats." from Mencken's 1919 Prejudices

Bikes 1993 K1100 LT, 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 for now


often the sensor connections (wiring side as well ) can be corroded get some deoxit ???

also the threaded relief into the water stub can become corroded so that a higher than normal resistance between the sensor body and the water stub threaded section .

measure from the gearbox connection point (to battery ) and the body of the temperature sensor meter on low ohms , it should measure below 1 ohm if not remove the sensor and clean it and the threads up

I installed an additional washer (copper , soldered so that is presents a lead- tin surface ) between the sensor and the water stub body , I figured the aluminium washer that I removed was so corroded that some type of electrolysis had set up with the dissimilar metals and location

good luck

cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O


Life time member
Life time member
The temperature sensor provides the enrichmt function that used to be done by the choke.

When the engine is cold it has a resistance of around 2500 ohms. At normal operating temperature it drops to a round 250 ohms.

A dirty connection will make the engine run like the choke is stuck.

1994 K75RT
1994 K75S
1992 K100RS

1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175

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