Coolant Sensor, Again! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

LSGarage · 12-27-2009, 10:39 AM

Back about June or so I problems starting my truck ('86 S-10, 2.8 TBI). Someone told me that it could be the coolant sensor giving bad info to the ECM. They gave me a list of ohm vs. temp readings to troubleshoot with. I changed the coolant sensor and the truck began starting better. But as soon as it went below freezing this winter the truck wouldn't start again. After changing the fuel filter, it checked for spark but couldn't detect any. I checked the coolant sensor at 50 degrees with a another new one and found it about 2000 points off. I installed the new one and the truck started right up. The only difference was that I installed the new one without pipe thread sealing tape this time. Could that have been the cause of the failure of the sensor I installed in June? The original sensor lasted 20+ years and over 180K miles, the second lasted 6 months and 3000 miles. Did I just get a bad sensor?

**truckdude239** · 12-27-2009, 11:39 AM

you could have but u never install a coolant sensor with pipe tape on it because the sensor grounds out to the head and witht the tape it prevents the ground

LSGarage · 12-27-2009, 01:02 PM

That's what I was thinking too. I just went out to start it again, temp was 37 degrees, truck won't start. Fuel pump runs longer than normal, even runs after key is off. I'm thinking now that there is (alot of) water in my gas tank and it freezing around the fuel pump. Anybody got any other thoughts?

12-27-2009, 10:39 AM	#1
LSGarage Registered User Join Date: Aug 2005 Location: Mechanicsburg, PA Posts: 86	Coolant Sensor, Again! Back about June or so I problems starting my truck ('86 S-10, 2.8 TBI). Someone told me that it could be the coolant sensor giving bad info to the ECM. They gave me a list of ohm vs. temp readings to troubleshoot with. I changed the coolant sensor and the truck began starting better. But as soon as it went below freezing this winter the truck wouldn't start again. After changing the fuel filter, it checked for spark but couldn't detect any. I checked the coolant sensor at 50 degrees with a another new one and found it about 2000 points off. I installed the new one and the truck started right up. The only difference was that I installed the new one without pipe thread sealing tape this time. Could that have been the cause of the failure of the sensor I installed in June? The original sensor lasted 20+ years and over 180K miles, the second lasted 6 months and 3000 miles. Did I just get a bad sensor? __________________ 67 GMC 4x4, 305 V-6, 4-spd 86 S-10, 2.8 2WD LWB 01 Suburban (family hauler) 13 Honda CRV (wife's wheels) 03 Malibu (daughter’s car)

12-27-2009, 11:39 AM	#2
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,259	Re: Coolant Sensor, Again! you could have but u never install a coolant sensor with pipe tape on it because the sensor grounds out to the head and witht the tape it prevents the ground __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2015 toyota Tacoma Daily 2012 Subura outback 2000 Tahoe 5.3l 420k 1999 honda accord General manager for Marco's Carwash & lube

12-27-2009, 01:02 PM	#3
LSGarage Registered User Join Date: Aug 2005 Location: Mechanicsburg, PA Posts: 86	Re: Coolant Sensor, Again! That's what I was thinking too. I just went out to start it again, temp was 37 degrees, truck won't start. Fuel pump runs longer than normal, even runs after key is off. I'm thinking now that there is (alot of) water in my gas tank and it freezing around the fuel pump. Anybody got any other thoughts? __________________ 67 GMC 4x4, 305 V-6, 4-spd 86 S-10, 2.8 2WD LWB 01 Suburban (family hauler) 13 Honda CRV (wife's wheels) 03 Malibu (daughter’s car)



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