Could be the ECU's going bad? When it won't start, does the CHECK ENGINE light come on when you put the ignition switch in the ON position? If not, that indicates the ECU is not powered up.

 

Could simply be corrosion on the terminals that the relay plugs into. Also good suggestion check for a CEL before you crank the engine.

 

The EFI Relay supplies power to the Circuit Opening Relay, which in turn powers the fuel pump. The next time it fails to start, try removing the COR, cleaning the contacts with electrical contact cleaner. ... Problem could also be something wrong with the fuel pump. They seem to fail occasionally.

 

Thanks for all of the suggestions and comments! Next time it fails to start I will pay closer attention to the check engine light, though I'm pretty sure it does come on when the key is in the "on" position.

Unfortunately, I can't create the problem on-demand to test a lot of things.

I like 71corolla's idea that there is something wrong with terminals where the relay plugs in.

I can't explain why taking out the relay and putting it back in would have any effect on the ECU, the COR or the fuel pump. And as you see from my experience this always gets the car to start. I admit I'm not very knowledgeable about electrical systems but I assume once the car is shut off and the relay opens it is no longer energized and can not affect any other component when removed and then put back in.

 

try using starter fluid

Buy a can of starter fluid ... ether ... The next time it doesn't start, remove the air filter and put a short burst in the air intake. If the no-start condition is related to lack of fuel, the ether will allow the engine to run for a few seconds. If that is the case, then it is the fuel pump, or one of those relays that is the problem. ... Seem to recall that fuel pumps can be intermittent, or weak when they are failing.

 

Please help me my Toyota Corolla start and drives for 200 meters then the engine stops.i try to start it fails I wait about 20 minutes try it starts drive again 200 or 300 meters stops so what is the problem

 

try hitting the petrol tanks bottom while you crank the starter, if the engine starts fault could be either pump is going bad or loose connection to the fuel pump's spades terminals.

 

It would be helpful to know the year of your Corolla.

 

Sorry for being late to the party. Was there a happy ending to this thread?