Check out some similar questions!

1Radford · May 25, 2008, 10:25 AM

Where is this located is it the one on the bottom of the radiator or on of the three on the waterneck coming out of the head (1 is vacuum other 2 is electric)? My car would die after a short trip and would not restart for 2 to 3 hours, I had 2 different mechanics look at it and no one noticed until I did this morning that the fans was not running. Called auto parts supply they said to turn on a/c to see if that made fans run and it did was told it is the temp sensor just not sure which one. Also found out catylitaic converter was plugged, for temporary fix I knocked that out to try and figure out all of problems first it now runs with a/c on but it runs poorly. When this first occurred I replaced plugs, wires, cap,and rotor. I'm not sure if it is running poorly because of converter being cleaned out or if it is something else top look for. Seems like it is not getting enough fuel when taking off. Very hesitant and sputtering.

Stratmando · May 25, 2008, 12:05 PM

Did you change fuel filter? If you have a multimeter, check continuity across sensor terminals(disconnected from harness). With engine cold it should be open, when it heats up it closes completing circuit.
Verify power to 1 side of sensor, key may have to be on. Many don't, so the fan can keep running when engine is off and hot.

kitch428 · May 25, 2008, 12:33 PM

Not fuel, it's the spark. Replace the coil in the dist first. Then run up to normal temp to see if fans come on. @ 212* or a little less, they should. If your bottom radiator hose is still cool at that point, then the sensor at the bottom of the radiator is not seeing proper coolant flow.
If you're going into the red, then I would suspect a plugged radiator, or stuck thermostat.
The reason I suggested the ignition coil first, is that is the most common problem for the issue on your model 4 cyl Camry. If the coil on yours is external mounted outside the dist, try sugg #2 below.
The second most common is the engine coolant temp sensor on the water neck. That is the EFI temp sensor. (ECT) The eletrical one, not the vacuum one. This IS a fuel related fault.

1Radford · May 25, 2008, 08:04 PM

It only seems to run poor under 2000 rpms. If I get it to rev over that it smooths out and seems to have normal pickup over that limit. It won't hardly go into gear without stalling many times but if I get it in gear and can go over 2000 rpms it runs fine until below 2000rpm. It was sensor on bottom of radiator that was bad and not letting fans run. Also when trying to start it backfires though intake. Timing appears to be correct.