SoFlaZ06

thanks for the tips, I'll give the tach a shot. and as you mentioned that, I did connect the noid light directly to the coil, and it flashes during cranking.

I'm using a noid light at the injector connector (at #6cyl if it matters), I have fuel pressure, around 32-35psi, I have spark, pulled plugs, they were dry, I put new plugs in anyway. and Pin #1 at ecu, i'm getting 12.8V, which is powered by the coil negative. I swapped coil with the test car, just to confirm it's worked and vise versa, with the plug wire disconnected, I'm getting a nice strong blue spark from it, it also lights up my inline spark plug tester light. the cold start valve is and thermotime has been disconnected, but is has been since I got the car. it's a southern car that live in 80 degree weather. on the relay/resistor side of the injector connector, I'm getting 12v there, which is getting power from the drop resistors, which is getting power from the Fuel injector main relay. on the ecu side I'm 12v also, which I believe it's getting from the #4 pin, powered by the fuel pump control relay. at this point My brain is focusing on why the grounding isn't happening through the pcm. I even tried back feeding grounds directly from battery negative to the ecu pins #35, 17 etc. what other failed instrument can cause this, what am I missing that the ecu needs, since the engine is from a ZX, I found some splicing happening for the AFM and throttle valve switch. But I remember the car would still run when I unplugged TPS before this fiasco, This 70s technology is new to me, not sure how smart or dumb this computer it. just looking for ideas to put my focus. luckily the pcm is only like 24 wires. I'm torn between rewiring, megasquirt or just carb it at this point, my head hurts This is my schematics and my notes.

Round 3? After confirming I'm getting power at both injector connectors, I did the trouble shoot in the FSM, at this point it told me to replace the ecu. my buddy has a 77, I started using his as a test car, I put my ecu in that car. his car ran with my ecu. I put his ecu in my, still no start. So what other input does the ecu need to signal these injectors to open? Another thing, my car has a ZX engine, from what I've seen the AFM and tps is different, some wiring was done there. just wondering where to aim my focus at this point. When I ground the injector connector to the battery, my noid light will light, confirming it needs a ground signal to open the injector. Another plot twist, it will randomly and very rarely run out of the blue while i'm diagnosing. which I hate, because I have no idea why, this time it died after running for like 20 seconds, tried firing it up again, and nothing. but it shows the car is capable when it wants to be

Edit: I believe I made an error here, and I did check it another 2-3 times, and it didn't show continuity. I you're right, it was coming from the drop resistors

Now I started testing the harness between the ECU and injector. as I was checking continuity to verify the injectors is connected to the ECU, I found ECU output (pin 32) which goes to cylinder 3 injector, has continuity at Cyl 1,3, and 6 injector connectors. I'm going to open the harness to verify the fail point, since each injector has there own ecu pin, continuity across 3 injectors isn't suppose to happen. Edit: made an error here, I indeed was testing the wrong side of the connector, the injectors are parallel via the drop resistors, hence the read continuity.

Right, as I dug into the car, I started finding bandaids along the way, as I repaired them, it's no longer apples to apples comparison, and pretty much having to start from scratch. I replaced the ignition, replaced and verified the ignition relay, also found a jumper wire that by passed the fuel pump control relay

Still chasing this, I'm narrowed it down to the injector isn't getting a signal. I have spark and fuel pressure, the injectors just isn't firing. I'm getting 12v to one side of the injector connector ( the relay side) when all the injectors are unplugged, but not at the other side of the connector (which is the ecu side of the harness), when I plug the other 5 injectors in, I'm getting 12v on both side of the connector, but it still wont light my noid light. But from what I've read, the ECU grounds the circuit to fire the injector. I tried my ecu in an 77 test car I have here, that car run with my ecu. but the test car ecu in my car doesn't change anything. I'm getting 12v to the ecu which it get from the coil - negative terminal. So it appears my issue now is the harness, between the ECU and injector connectors

oh wow, thanks. I was way off then, I was way by the passenger footwell area.

ok so I have spark, I can prime the fuel system in the accessory position, the fuel pressure gauge will peak at 36psi, sometimes it'll hold it during cranking, sometimes it won't, I'm not sure how the fuel relief is setup on these cars. but the fuel pump definitely isn't running on the "on" or "start" position. So I went back to the ignition switch, I have constant 12.5v from the White/red wire, in the ignition Acc position, i'm getting 12,5v there too, that's the blue/red wire, in the ON position, I'm getting the 12.5V there also. from the switch to the fuse box, and leaving the fuse box. During starting phase, the black/yellow wire is reading 12.5V also. So assuming the wiring isn't mixed matched. the ignition switch checks out as functional. The schematic I have doesn't identify the colors. No i'm trying to figure out which is the Fuel pump control relay and which is the fuel pump relay, so i can start testing there. I see 4 relays on that bracket Which is which? and here's my schematic sheet i'm working with

I have a 1978 280Z, I'm new to the Z and this platform and looking to see what direction to start diagnosing this. So i'm driving one day, and car just dies. It will turn the engine over, but won't start. it appears everything electrical if off when the key in in the "On" position. then I noticed the switch is working funky, but I haven't had the car long enough to confirm is this is abnormal. but i appears to be working backwards, like everything (gauges,fuel pump etc) turns on when key in the "Acc" position, but turn off when in "ON" So I figure the switch is bad and wanted new keys anyway, ordered new ignition, same problem Where do I go from here? where can I get schematics for these cars I tried manually engaging the starter, with the key in the "acc" position, to see if it'll run since the fuel pump etc is running, but that didn't work :cry

i'm curious what you find out, i have some slop in mine also

comes down to location really and what other examples in your area. the further away from the west coast, the price goes up. I don't believe there such thing as a rust free datsun, but rather how much rust you're willing to deal with, But if it is what he says it is, then I think the price is fair. get underneath the car, that determines the price.

nice work, i'm curious what it weighs. I'm torn between a Z on a diet vs a clean resto. both opposite sides of the spectrum