Where is located the EFI main relay for a toyota previa 91?

efi main relay,circuit opening relay,airflow meter door stuck..need more info and i can tell you how to fix or at least where to look.

The short will be in the fuel pump.

Here's how to check the injector circuit.
Pull off one injector connector and with a testlight grounded on the engine, turn key to on. Probe the terminals of the injector connector. One of the terminals should have steady power from the ignition being on. If neither terminal turns on the testlight, the injector drive circuit is not working. There may be a fuse for the injectors out. Also check the efi fuse, located I think under the hood. If still no good, you will have to check the circuit from the ignition switch to the injectors.
If you got a steady light from one terminal, the drive circuit is good. Now check the ground circuit: Put the lead of the testlight on the positive battery post, and put the probe of the testlight into the injector terminal that did not light up.Someone will have to crank the car over for you. If the testlight is blinking when the car is being cranked, the injector circuit is working right. The blinking light means the computer is properly grounding the injector circuit to fire the injectors. The ground circuit leads direcdtly from the injectors to the computer. When the computer internally grounds that injector, the injector will pulse, or fire. Good luck, and I hope you find the problem.

Have you checked to see if it has spark at the spark plugs, let me know. Actually there are two relays for the fuel pump, the EFI relay and the circuit opening relay, the circuit opening relay gets voltage from the EFI relay. If the computer doesn't get a spark confirmation signal while cranking then the injectors are shut off.

I had check the spark at sparkplug because the crank and cam sensor send a signal to the computer who trigger the coil driver and injector driver. check voltage at injector wire and ground. One wire on each injectorshould have 12volt ignition on. The computer trigger the ground. For the spark use a SST225 it is cheep

Check the EFI main relay, the circuit opening relay, and the fuel pump relay. Inside the fuel pump relay there is a switch controlled by a coil. During start, the fuel pump gets full power for a couple of seconds to build up pressure. Once pressure is good, the fuel pump relay is supposed to switch (via the coil) the fuel pump to reduced power. If the coil in the relay is bad, the reduced power setting is not available and the fuel pump will run at full power all the time. At this heavy current draw, it won't be long until the EFI fuse blows. This would also give more pressure than is necessary to the cold start fuel injector which runs on a timer. This extra pressure during the time that the cold start injector is operating may be the reason the engine is flooding with fuel.

could be the cold start injector or cold start injector sensor








Butch4est

try to change the coolant temp sensor.

1. make sure you really have no fuel delivery. open a line convenient for you as in cold start injector or fuel filter, disconnect ignition coil lead and crank away a bit to make sure you're not getting fuel.
2. I assume you're getting spark.
3. check efi fuse in main relay box passenger side inside right fender. if good check that you have juice at the Co relay hidden in the passenger kick plate. its the white-red terminalwhich delivers the current. the Circuit opening relay is really the main enchilada for getting the pump up and adam.
4. still no go. you have to address the Co relay itself. test terminals with ohm tester. also you can jump wire the Bp fP terminals in the diagnostic connector on the side of the main relay and see if the pump goes.
5. and lastly it might be the pump itself

2 things come to mind.. Fuel pressure regulator.. and Leaking injectors..