Nissan Repair: Pathfinder will not start., nissan 4x4, fuel pump relay

Question
QUESTION: My 1993 Nissan 4X4 3.0 auto with factory alarm system will turn over but will not start. A little history  of the car in the last year a new fuel pump, fuel pump relay, timing belt, new plug wires, distributor cap,  rotor button, plugs have been installed. I have checked the timing its dead on, I checked to make sure its getting fuel and it is, checked for spark out of the distributor and at the plugs and it is getting spark. It will run if you spray starter fluid into the air intake.  I also checked for power (voltage) at the injectors and I have NO voltage there? So I’m thinking there lays the problem, but not sure what to do next? One more thing the car has 150,000 miles on it and runs great when its running. Oh yeah over the last 6 months you will be driving it and it would just stop running, if you disconnected the battery then reconnected it  the car would start back up. I installed a new (used from junk yard) engine control module. (The computer under the passenger seat) and it did nothing to help my problem. Any help you could give would be great.
Thanks
Anthony

ANSWER: Anthony,

The way the fuel injection works is the computer grounds each injector when it is time to inject fuel.  These circuits pass through the fuse block and you will need to see if the circuits are working.  Backprobe as someone cranks the car.  If you have a test light or a noid light you can disconnect each injector and check the harness connections there first.  But, from the sound of it you have a power problem like the relay is not closing or the circuit breaker/fuse is not providing connection.  Check these two and email me back.  I would not think a second ECM would have gone bad.

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QUESTION: no voltage at any of the injectors with the motor being turned over. When you speak of the relay what relay are you telling me about? The fuse at the battery is good. I looked in my fuse box and don't see a "injector" fuse there. Under the hood on the right hand (passenger side) is a relay block on is for the fuel pump another is for the main relay? Not sure what the main relay does? A check relay and a horn relay. Then they are something like 3 maybe 4 other relays just bolted to the right side I cant find any info on these ones. On the left side the are 2 other relays bolted to the side and I have no info on these. Thank you so very much time in helping me but this thing has me lost.

Answer
Anthony,

You really need a wiring diagram so get a Haynes or a factory service manual to do the tracing.  Anyway, the way the system works is the injectors are grounded when they are to fire by the ECM.  Power is provided and the computer grounds each injector when it is time to fire.  When the vehicle is started the power is provided via the injector circuit.  The ECM is powered seperatly.  You should have an injector fuse that feeds power to them.  This is different from the ECM.  Also, the ignition is a seperate feed too.  Check the fuse panel under the dash as there are usually four relays just above the fuses.