1992 Temp Gauge Crazyness

Ok my temp gage is jumping all over the place. Its happens when the car is not even running ( key on) so I know its something electrical somewhere. The car ran fine up until July when I bought a new gas saving 4 cylinder car. The blazer only was driven on the weekends and now it seems to run terrible. Anyone have any ideas what’s going on? CPI and nut set has already been replaced. Needs an inspection but wont pass with the miss it has now. I have a feeling the jumping gauge has something to do with this somehow. Ran great until it sat for some time. Can’t see any spots were mice may have had a feast. Any help would be much appreciated. This ever happen to anybody out there?

I saw a post recently where a fellow had a temperature sensor go haywire and it was telling his computer that it was below freezing all of the time, so it pumped far more fuel into engine than it needed and it missed and carried on. If your guage is messed up that might be a good place to start. I think you have two sensors, one to the guage and one to the ECM. Might d/c that though, to be sure. If it were just a miss I might suggest a tune up, fuel filter, IAC cleaning, EGR cleaning, spark plugs/cap/rotor button etc. I think this was discuused in the Blazer forum just a couple of weeks ago...

Thanks for the speedy reply. I did the tuneup but that did not help. I only see one temperature sensor in the front of the engine. I will try to replace that and see what happens. If there is another sensor do you have any idea where it is hiding? also the only other thing I did was replace the leaking heater core, I dont believe i knocked any wires off but I will have to check the ECM area again as there were many wires in the area. :banghead:
Thanks

I saw a post recently where a fellow had a temperature sensor go haywire and it was telling his computer that it was below freezing all of the time, so it pumped far more fuel into engine than it needed and it missed and carried on. If your guage is messed up that might be a good place to start. I think you have two sensors, one to the guage and one to the ECM. Might d/c that though, to be sure. If it were just a miss I might suggest a tune up, fuel filter, IAC cleaning, EGR cleaning, spark plugs/cap/rotor button etc. I think this was discuused in the Blazer forum just a couple of weeks ago...

I was told one on each side of the motor, but I have not looked on mine yet(93). On the Blazer forum one of the fellas there said there is two, one supplies information to ECM, one to guage. I seem to remember that they are not easy to spot... Might want to pick up a Haynes manual or do a search on the Blazer forum. A lot of S-10 folks post on there since many are s-10 Blazers. I will look at mine when I get time.

Ok ran out today and grabbed a new temp sensor and it did the trick. No more eratic gauge. To bad the car still is running rough though. I took a quick look inside the intake manifold and it looks a little wet. The CPI and nut set was replaced 40k miles ago, think it could have failed already?