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1998 Johnson 90 HP

M

movari

New member
Been having problem with the temperature at high speed. At idle it is at 160, but at full throttle it goes to 220. Changed the impeller and bought new thermostats and still the same. Running without thermostats it sits at 160 ish. johnson 1998 temp sensor.jpg I checked the resistance on the sensor and it had 700 ohms at 65 degrees and 60 ohms at 212. Not sure if this is correct or not. It looks to be the original guage on the four winns boat. Does anyone know if this is correct part? I couldn't find one in the parts list for my J90ELECM model
 
If alarm function and have never sounded it is not getting hot. Your sender or gauge is quirky and these often cause people to start chasing ghost problems. better to have a pressure gauge as you can monitor the wear on impeller and results are instant
 
Thanks for your response
. I was thinking that really there may be no issue. What temp generally triggers the alarm if you know? Also, for these types of motors, what would be a typical operating temp range at idle and then how much increase at full throttle. I would imagine an increase but don't know how much
 
Thermostats control lo speed cooling by opening at 143*f. I like to see hi speed in the 160-180*f range. Again,does your warning horn work? Last time it had a waterpump?
These temps are taken with a temp gun
If i remember correctly,tan/blue temp wire sounds horn at 205*f.
 
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Thanks for the input. I never heard the alarm. You are correct about the wiring brown with blue stripe. Of course I don't know if the alarm is working correctly, Not exactly sure how to test the switch in the alarm circuit out. All in all it almost seems like the thermistor and the guage as a pair are skewed high and as you say if the alarm is to at 205 and the gauge reads 220 at full throttle, than unless the alarm is not functioning, than that seems most likely.
 
With the key in the "on" position,hold tan/blue wire to ground (block,head bolt).horn should sound.
Horn should also "beep" each time you turn key on,assuming your controls are the same year as your motor.
 
Thanks. When I turned the key, I heard the beep and I saw the slef check pattern of no oil, low oil and Hot. Funny, I assumed the alarm beep when turning the key was the depth finder alarm as usually I start in shallow water where the dock is.
 
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