2000 Toyota Corolla Won't start when it's hot

Assuming you are not getting any error codes, I would think it is fuel related (pressure).
Check the pressure during the event with a mechanical gauge see what it is.

I would also have the PCM scanned (any auto parts stores) to see if there are any pending codes.

I don't have any error code. But I was told to have my ECT (engine Control Temperature) or coolant Temp sensor replace.

doesn't this make any sense?

Thanks,

Kit

It is possible, but if these sensors are out of range they should set a code.

Have the car scanned in live data mode and see what the sensors are displaying, compare this to the normal range to isolate the problem.

No check engine display and no error code present, I just replaced the Coolant temperature sensor. I still have the same problem hard to start and excessively cracking ONLY when the engine is running HOT. Could it be the fuel pressure regulator or the fuel pump? Today, I started the car and rev the engine several time. The engine felt like it was going to shut down everytime, I rev the engine.

1) does this model toyota corolla 2000 have a fuel pressure regulator? If yes where is it located?
2) Do you think fuel pump is failing or fuel filter clog?

I really appreciated you time and help thank you very much.

Kit

The regulator is located on the fuel rail, it has a vacuum line at one end and a fuel return line.
Check the vacuum line for gasoline, if present, then the FPR has a ruptured diaphram and would need to be replaced.

To check the pump, have the fuel pressure tested with a mechanical gauge. Most cars have a test port on the fuel rail, Toyota's may or may not. Eariler models had a special fitting that screwed into the rail at the cold start valve (after removal of CSV).

If fuel system checks out (I would replace the filter if it has never been replaced). Then it could be an ignition problem (crank sensor for example). The PCM monitors misfires and should set a code.

The last tyme I had this problem, my mechanic traced it to the fuel filter. It was clogged with dirt. The reving became smooth after he had changed the fuel filter. With the starting problems, your car computer may be gettiing an 'engine overheating' signal. engines will not start when overheating is detected.

Did you find out what was causing this problem? My corolla is doing the same thing. Thank you in advance for any help you can give me.

Without any error codes, the fuel system would be the first suspect.

Have the pressure measured with a mechanical gauge.

This is a good starting point.

While there are many possibilities, start with fuel pressure, an erratic fuel pump or clogged filter are good starting points.

Next would be ignition (crank/cam sensor) and a clogged or partially clogged CAT.