1975 280z Electrical Issue

[Barefootdan]

26 minutes ago, Zed Head said:

You might check the circuit, continuity, from each injector plug to the ECU connector.  14, 15, 30, 31, 32, 33.  You might use the NOID lights in place of injectors to complete the circuit, for testing.

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 Head]

Injectors can't really be fixed so if those others are open circuit, they're toast.  It's weird that they are open though, I think that they usually short circuit internally, or just get jammed mechanically

@Terrapin Z might have some used injectors to get you started. If you're not sure where your project is going to end up.  He has a hoard of parts.

You could also buy just one injector and see if you can get one to work right.  Still odd also that your NOID lights didn't work.  Are you sure they had a good connection?  You used a jumper instead of a NOID light.

[Barefootdan]

53 minutes ago, Zed Head said:

Still odd also that your NOID lights didn't work.  Are you sure they had a good connection?  You used a jumper instead of a NOID light.

On 3/16/2021 at 6:37 PM, Barefootdan said:

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). 

 

On 3/17/2021 at 6:25 PM, Barefootdan said:

@Zed HeadAnother update today. I was able to get continuity from the (-) coil pole to the ECU pin #1. Progress!

 

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 🙂

[Zed Head]

If the NOIDs work the injectors should work.  I don't know your budget but I've found that salvage yard Bosch and Nissan injectors can still be just fine if the rail holds pressure.  Any Z or ZX, just cut the fuel line and see if fresh fuel squirts out.  If it does get the FPR too.

There's still a bunch ahead of you but looks like you're almost there.

[Terrapin Z]

9 hours ago, Zed Head said:

 

@Terrapin Z might have some used injectors to get you started. If you're not sure where your project is going to end up.  He has a hoard of parts.

I do have some stock Nissan injectors, if you want to go that route, just let me know.  

[S30Driver]

If the ECU becomes a issue, this one was known good from a running 75 280z,  A11-000.   Replaced with the FAST efi system.

Edited March 19, 2021 by S30Driver
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[Barefootdan]

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

[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? 

[Patcon]

Many cars aren't well timed when it's near the middle of the slot. You could always loosen the screw a little and use a leather glove to rotate the distributor while cranking to see if you can get a little better result

[Zed Head]

43 minutes ago, Barefootdan said:

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.

One thing of note is that the new plugs look awfully charred after just cranking. Too much fuel? 

What resistance number did you get from Pin 13?  That's the coolant(water) temperature sensor.  High resistance makes the ECU think you're in the Arctic.  Adds lots of extra fuel.  Pretty common to have a problem there.

You could disable the fuel pump and see if it dries out enough to start with fluid.  It will give you a clue about timing.

[Barefootdan]

Just now, Zed Head said:

What resistance number did you get from Pin 13?  That's the coolant(water) temperature sensor.  High resistance makes the ECU think you're in the Arctic.  Adds lots of extra fuel.  Pretty common to have a problem there.

You could disable the fuel pump and see if it dries out enough to start with fluid.  It will give you a clue about timing.

I am sitting at 2550. I think... I see 2.55 when I have my multimeter on the "20K" setting. 

[Zed Head]

The other "extra fuel" thing is the cold start valve.  Somebody just had that problem.  Your resistance looks about right, chart below.  You can disconnect the fuel hose and plug it for a test.  It will have full fuel pressure behind it so be careful.

Something for the back of your mind - the ECU's often go super rich before they fail completely.

Too bad, no quick fixes for you.  Looks like you're on the marathon route.