WHER IS FUEL INJECTOR RELAY LOCATED FOR 2004 MAXIMA

Fuel injectors don't have a relay . A fuse supplies battery voltage to one side of the injector ,the other side goes to the engine computer for control . Your best bet ,have a qualified repair shop check it out .

Within the fuse box, look for fuse number 9, it is a 20 Amp fuse and is used for fuel pump relay, Fuel injectors, Injector sense, and Intake manifold runner control. The relay for the fuel pump is relay number R303.
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Computers do not use relays. Computers use large transistors (A.K.A. "drivers") to control things like relays, solenoids and injectors.

That being said, your Nissan is equipped with "sequential multiport fuel injection". There are 6 injectors, all of which are supplied power from a 15 Amp fuse in the underhood fuse and fusible link center. The white wires at each of the injectors is hot (Battery Positive voltage) at all times, even with the ignition switch OFF. The drivers in the computer (or ECM)toggle the other wires on each injector (each injector having its own wire color) to ground (Battery Negative) in order to complete the injector circuit and cause the individual injectors to fire at the proper time. This is what is known as "injector pulse".


To sum-up, there are no relays involved in the actual injector circuits on your Maxima. The only relay that is remotely related to the injectors is the ECM Power Relay which supplies power to the ECM. Since the ECM will not function if this relay is defective, neither will the injectors work if this relay is faulty.

I hope this helps you to understand whatever it is you are trying to figure out.

Assuming they used any sense at all when they built that motor it is transverse mounted and the starter is located on the front side where the transmission housing and motor come together. Unfortunately that means it is located partially below the exhaust manifold and you will have to remove most of the intake manifold to get at it.

Fuel injector #4 is for engine cylinder #4, below is a diagram of the engine cylinder layout. So #4 is the center engine cylinder in the front bank of cylinders, the front bank is the 3 ( cylinders 2,4,6) engine cylinders closest to the radiator.

check the fuel pressure to injectors to see if pump is working properly. there should be a schraider valve on engine fuel line under hood to test this. the ecu is located on floor directly behind radio. there is a black cover with 2 round plastic snaps that cover ecu. from drivers side, ecu is beside gas pedal. pull on the ecu cover to remove it. are all fuses and fuel pump relay ok !!

its under the hood in the fuse box .

Inertia fuel shutoff (IFS) swicht location in instrument panel below radio.Thanks

There are 2.
One is on the side of the master, and one is located on top of the slave. Some aftermarket slaves have them on the bottom.

The fuel pump relays are mounted on an "L" bracket underneath the ECM. Both have something to do with the Fuel pump. Be careful not to get it confused with the horn relay it is in the same vicinity (under the dash on the drivers side).