Been looking around for ideas on how to get my car running. I know this is a dumb question but I cant figure it out.

The injectors/fuel pump do not work, I just want to know what could be the cause.
Since the car will not start I did a voltage check on the ecu with out warming it up. This is what I got for the injectors. Is this information accurate or useful since the car hasn't been warmed up?

.01V for Injector (rear primary)-Should be 12V
12V for the rest

 

Injectors and fuel pump are separated. The fuel pump will not turn unless the car is running, the key is in the start position, or the fuel pump test jumper is jumpered.

There's a two-socket connector near the passenger's strut tower. Short the pins with the ignition on, and the fuel pump should run.

For the injectors, there are several reasons they won't work.
1. They're gummed up and won't cycle.
2. They're not getting power (there should be +12v on one pin of each injector connection).
3. They're not getting grounded by the ECU to fire. This is often due to bad ECU grounds (the ECU can't sink the current), or on rare occasions bad driver transistors in the ECU.

Depending on how many spare parts you have and how comfortable you are taking the engine apart, you can test the primary injectors on the engine. It's easiest if you can either remove your crank angle sensor or use a spare one (restabbing the CAS can be a pain). Disconnect power to the spark coils so they don't fire (the snap of the spark isn't what you're listening for). Spin the CAS with the ignition on, and you should hear the injectors snapping on the passenger's side of the engine.

If the car sat for a long time, the injectors are likely gummed up. I had a car that would not run at all - turns out all 4 injectors were gummed up.

However, the 0V reading on the rear primary injector is a bit worrying - with the ignition on, as you noted, it should be 12v. Check the connector - if it's not connected to the fuel injector, that will cause the issue. A burned out injector will also cause that.

Since you've got a NA, all 4 injectors should be 460cc - you can swap injectors if you determine the injector is bad. If you have a bad secondary, you won't be able to go past 3800 RPM under load, but it should start and drive.

-=Russ=-

 

Wow thanks thats some good insight! Ill look into it first thing.

 

No 12v to the injectors? Could be a couple of things. EGI fuses in the engine bay fuse box kaput for one.

Number two would be a kaput ENGINE fuse in the interior fuse box.

You turn the key to ON. The Main relay closes and feeds 12v from the EGI fuse to the injectors. The 12v passes thru the injectors and ends up on the fuel injecotor wires at the ECU. You have no 12vdc so it must be one of the fuses......IF you have not disconnected the harness b/t the Front and EM harness........or??

 

But he had 12v on 3 of 4 injector lines. Only the rear primary wasn't getting 12v. So it's likely something with that specific injector's wiring, plugs, or internal condition.

-=Russ=-

 

ERRRR....I'm semi illerterate? Yes My bad.

There's an open b/t the Solenoid resistor package and the injector or b/t the injector and the ECU, one.

Not hard to figure out. PUll the intake off and pull the rear primary injector plug off and check for 12vdc on one of the two wires. The BROWN/RED wire should have 12v. Probably a half *** crimp on a injector wire. No big deal. Fix.

 

ok I took off the intake today and looked around, i guess I should have looked here before I posted a new thread. From the looks of it the fuses are fine. I checked all the fuses inside next to the clutch pedal they all are fine. One of the injector cables has been cut and simply twisted back together. There are three injector cables at least I assume. A half *** job, but I dont know why they did. There are pictures here. https://www.rx7club.com/2nd-generation-specific-1986-1992-17/why-three-injector-connectors-673628/ Also primary injectors cosmetically look crappy so im thinking the injector itself may be a problem. Still kinda lost on the injector cables subject. Ill let the pictures do the talking. And yes i know it may be a simple fix but I still need to gain some familiarity on the fuel/electrical system.