Barefootdan

Injectors are in and working I believe. Still no start... I checked for spark again and do see it. Plugs are also wet and smell of fuel so it is no longer fuel issues I think. I tried spraying in starter fluid, still no luck. I'll get a rare backfire out the intake. But I cant duplicate it on demand. This makes me think it is a timing issue? I checked the distributor and plug order twice. No issues there. I placed my cap midway in the adjustment slot. Next step is compression test...then check for correct timing? Not sure what else to do. One thing of note is that the new plugs look awfully charred after just cranking. Too much fuel?

Thank you all for being so helpful. I ordered up a set of injectors the other day. They should be in soon 🙂

I think my NOID didnt work in my first test since I didnt have continuity from (-) coil to my ECU #1. It wasnt until the next day did I fix the continuity problem. I need to head to the parts store to rent the NOIDs again 🙂

BINGO! Placing a jumper in place of the injector gives me 12v at the pin!!! I assume this means I need to order up a set of injectors to see whats next?

@Zed HeadRe-ran the EFI relay test. Clicked over at 12v and had continuity between the two test pins. I tested each injector, all failed the 9v battery test. Also, all failed the continuity test from page EF-57: Continuity check <• "; 1. Disconnect ground cable from battery. 2. Disconnect, electric connectors from injectors. 3. Check continuity between the two. terminals. Continuity should exist. If not, injector(s) are faulty. My thoughts now...Since all 6 injectors are bad (and they sure look the part with some nasty corrosion) and they are wired in a series(?) that the current is not able to flow through them to the ECU. The ECU then never has a chance to ground or fire them. This would explain my failed NOID light test. Thoughts?

Ah! I will need to test this. I was following page 63 asking for battery voltage. I did test the dropping resistors yesterday. Unplugged them and tested the resistor directly. Spec for all 6 injectors was 6 ohms and I was hovering between 7 and 8 for all. I am using a cheapy multimeter though so I'd assume we are in a margin of error? I'll redo the EFI relay test. Since I heard a click going to the START position (or rather felt it) I moved on. Looking at that diagram, it doesn't seem that the EFI relay would be the cause of no volts to the ecu though? Unless I am misunderstanding. I will say that the fuel pump does run when my AFM flap is moved and it looks to run through that relay.

I did, i have no voltage on any of the injector pins. I tested injector #6 so far (ran out of time) and had no clicks even after tapping the injector. I wouldn't be surprised if they are bad...registration shows it last in 1993! My big concern now is finding out why I am seeing power at 1 injector pin with only 1 injector unplugged and no power at any injector pins at the ecu harness. I will hop back out to the garage tonight. If I recall correctly, I had power at 1 pin, the other pin had power but I could see it dropping in my multimeter. Started at 12 and ends up at 0 after maybe 10 seconds?

Actually I am seeing power at 1 pin with only 1 injector unplugged. I'll need to go back and verify with all injectors unplugged what is happening. Also, ran out to test a manual zap of the injectors with a 12v battery. No go either. Could faulty injectors kill the pathway between the 12V pin and the ECU as power needs to flow through the injector? I.E. a faulty injector not a stuck one.

@Zed HeadAnother update today. I was able to get continuity from the (-) coil pole to the ECU pin #1. Progress! My next tackle is to why I am getting 12v at one pin of the injector, but not at the ECU pins for the injectors. This may also explain why the manual grounding of the (-) pole of the coil results in no injector pulse. It appears it is a straight shot from the connector to the ECU and I see no visible breaks. I may need to remove the sheathing.

After all this cranking I think my starter also went out 😞 I get spinning of the starter but not the engine. Going to swap it out in the mean time.

Alright, did some testing. Got through the manual you linked until step 6.b where i need to test the ECU. From there I got until test #2 - 3(a): #4 Injector Circuit. I have no volts to this (or any) of my injectors at the ECU. Going to my injector, I do see 12v at one pin, the other does not have power. I moved to the FSM. Drop resistors checked out. Main relay and fuel pump relay click when moved to ON and START. I moved to the injector test. "Check continuity between the two terminals. Continuity should exists. If not, injectors are faulty". Am I checking for continuity of the injector itself? I receive none across all 6 injectors. I then picked up a NOID light test kit. But these are not lighting up either. Misc tests: NOID light showed no power when cranking. I have 12v at ECU pin 1, but not continuity from ECU pin 1 to (-) coil pack (jumper ran from (-) to inside the car to reach). Manually grounding the (-) pole of the coil results in no injector pulse. Manually grounding injector pins from the ECU results in no injector pulse. Confirmed i do get spark by pulling a plug and laying on valve cover. Strong and blue. Coil is new, plugs and wires as well.

That could be it...I did take the dash out not too long ago, I may have broken the connection. So my Coil to Tach is good, that is a good hint. I'll do some digging tonight 🙂

Awesome, I will walk through that as my next process. So far i dont think it is the ECU since I am not getting a connection from Pin 1 to Coil (-). Fingers crossed!

There is voltage at the plug (at least cylinder #6) when I check at one pin and ground.

Thanks Zed Head. I was able to find that jumping the Shunt between the large White and White/Red wire allows for continuous electrical to work. Strange...I tested the shunt separately and saw no issues with the fuse and continuity. I am stumped. I left the jumper in for now to allow me to diagnose other issues. Next, I am receiving spark and fuel...but injectors are not firing. I think my coil is not properly sending a signal via pin #1 on the ecu. I ran a jumper to test continuity from the (-) terminal of the coil to terminal 1 of the ecu and I have no continuity. Manually grounding the (-) three times does not fire my injectors as well. Any thoughts on what could cause the disconnect? The manual I saw shows a direct connection. But forums suggest the ignition relay perhaps. For what it is work, I am seeing my tach jump while cranking. Spraying starter fluid in the intake gives me the occasional backfire out the intake too. Plugs are dry.

Update! I cleaned and re-crimped the fusible links. No luck. I then made an alligator clip to jump the terminal instead of the fusible link and no luck. Lastly, I ran a jump from the Positive terminal of the battery to the receiving end of the fusible link...viola, power!! So there is some disconnect from the source side of the fusible link terminal and the battery. I may need to peel back the wiring to see. Unless there is an additional fuse prior to this box?

The two fusible links have continuity through them, although one could be fried. My initial test was testing the terminals directly. I had 12v at the White (alternator and IGN relay) terminal, but none at the White/Red terminal (IGN switch). But perhaps the terminal lost connection from below?

Hi all, New here, with my 1975 Datsun 280z. I am in the process of getting it running. I was able to get a new battery and start testing electrical power. I had the headlights and tail lights working, then began to start cranking. It successfully cranked for about 10 seconds. I stopped and tried again, but this time no power. I lost power to all lights as well. I took out my multimeter and tested the fusible links first. I have power to the White wires (closest to the fender) in the box. But zero power to the White/Red terminals (closest to the engine). I checked my power to the starter and confirmed 12v. I even jumped the solenoid and was able to see the starter working this way. I am a bit stumped. I tested the White/Red from the alternator to the battery and have 0v. Is this my issue? Is there a connection between the White starter and White Red Alternator that is causing my issue?