Datsun 280zx won’t start

[David F]

55 minutes ago, Zed Head said:

 

We need more "do" jimmyb.  Dave F could do some browsing too.  There's no CPS on the NA models.

Why would I do any browsing when I don't own a zx?  I was just trying to help and even said I had no idea if a zx even had a CPS...I guessed it might not.   Oh well, no harm in trying.  Hope the OP figures it out.  What type of system is it any? Bosch L Jetronic? 

[Jimmyb]

3 hours ago, Zed Head said:

The ECU is very sensitive the its signal from the coil negative post to the pin on the harness at the ECU.  You need to confirm that that path is clean and useful, as was said several times above.

Could be that engine started on CSV fuel, which turns off when the engine is started, or when the valve gets hot from its internal heater.

I've found also, that spark can be visible outside the cylinder, during a test, but too weak to start the engine.  In my case, starting fluid would start it but it wouldn't light up on gasoline.

You might also have a giant vacuum leak.

"Nothing" doesn't tell much.  No spark, no change in timing, no engine start....?  The answer often lies in the tiny details.  The FSM Electrical chapter probably shows where all of the relays and fuses are.

 

54 minutes ago, Zed Head said:

 

We need more "do" jimmyb.  Dave F could do some browsing too.  There's no CPS on the NA models.

I do, I did. But when it comes to cars electric I really do suck, I mean I have to google like 3/4 of all the terms people are using! 

I was saying above I'm not a mechanic, I'm a web developer. I just love cars, always had and love to work on them and l'm learning by doing (and asking you guys).

I've never had to dig this deep without any results and that's why I joined this forum, I need help.

 

"The ECU is very sensitive the its signal from the coil negative post to the pin on the harness at the ECU.  You need to confirm that that path is clean and useful, as was said several times above." - I haven't checked the pin on the harness at the ECU yet, I'm working my way there. The Spark is good, really should be good enough for the car to fire up. Vacuum lea yes, probably a more than one but nothing I can see, I would have to test with some starter fluid. But should'nt the car still start if there's a vacuum leak? I mean sure, it would run bad etc. but atleast start up?

Nothin = no changes = no change in timing and no engine start.

Btw, thank you for taking interest!

[Jimmyb]

To sum up tonights efford to get the car running

1. The green relay seems to work, nice clicking sound and feeling. That's the fuel pump relay right?

2. The ugly metal one - nothing. So I tried using a battery and some cables and yes, it clicks just fine. So I cleaned everything up and still nothing, took a cable from minus on the battery togheter with the ground pin on the relay and nothing. That tells me it should be somewhere between the ECU and the relay right? Couse as far as I can see on the xenon link that JSM posted there's nothing in between that could cause this exept maybe a broken wire or the ECU itself?

3. The fuel pump still wont start by itself (could be a broken wire though, because the relay seems to work), or the ECU again?).

One thing I forgot to mention was that I had to hot wire the car. I got the keys for everything but the ignition. So either this is a very stupid question or it was a extremly stupid move to hot wire the car, but could this have something to do with wht it doesen't start?

There's a black piece of plastic-isch where you put the key in but i mean common, some kind of a imobilizer in 1982? Nah, but I don't really know?

Are the ignition attached to the steering collumn some kind of important grounding point? I did put a wire between the minus pole and what's left of the ignition(attached img) just in case, didn't help.

So I don't know guys, I'm totally gasping for solutions here. And I want to say once again that I really do appriciete you all trying to help me!

Going to London, next try will be on sunday. Have a great weekend everyone.

/Jimmy

[Zed Head]

The fuel pump only gets power when the engine is running, when the key is at Start, and, if it's working correctly, a 5 second stretch of power when the key is turned on.  It does not just keep running when the key is at On/Run.  You didn't hot-wire the car you just moved the ignition switch.

There are two fuel pump relays, one's called the fuel pump control relay and the other is called the fuel pump relay.  My impression has been that they're both metal but who knows.  There's a diagram and chart in the FSM, EFEC chapter.

Theft prevention devices have been around for a long-time.  I assume that colored blob picture is the back plastic-isch thing?  Can't really see any of it.

From your knowledge level it would probably be best to go back to trying to start it with starting fluid.  That will define a good starting point for your other troubleshooting.  You've changed some things since it last ran and you might have lost spark or timing conditions that would let it run when it does get fuel.  If I was in your shoes, I'd confirm that it will run with fluid, make some best guess changes, and if they don't work reset everything and make sure it runs with Starting fluid.  If you don't really know the basics you need a good baseline to go back to, to reset.  Try some things, reset to "runs with fluid", try some more things.

[MarkZ]

Jimmy I am at similiar point with an 83zx I just picked up. Fuel to the rail, starts with fluid. Injectors don't open. I am pulling the fuel rail to clean all the injectors and to replace seals, gaskets etc this weekend. As I go through it I will keep you in mind as I troubleshoot my own.

Sent from my SM-G950U using Classic Zcar Club mobile

[Jimmyb]

Hi!

So. I’ve cleaned all of the fusible links etc. and now I do have voltage to the injectors, the wierd thing is that I got voltage on both pins on each injector connector. If I’m reading the manual right there should be constant voltage on one of them and then the ECU will ground the other one when I crank the engine, but I could be mistaken?

If I disconnect the ECU then I got voltage on one out of two pins on each injector connector, just like I believe it’s supposed to be. Are the ECU broken? Does anyone who knows cars electrics maybe explain this?

 

About the theft prevention, there’s this black thing where the key goes(attached img). Could this really be why the car won’t start? Feels a bit high tech for 1982..

 

Edit:

I got voltage all the time, nothing changes if the ignition is on or off.

Edited November 14, 2017 by Jimmyb

[Jimmyb]

On 2017-11-09 at 3:30 PM, MarkZ said:

Jimmy I am at similiar point with an 83zx I just picked up. Fuel to the rail, starts with fluid. Injectors don't open. I am pulling the fuel rail to clean all the injectors and to replace seals, gaskets etc this weekend. As I go through it I will keep you in mind as I troubleshoot my own.

Sent from my SM-G950U using Classic Zcar Club mobile
 

That's awesome, cool cars. I hope you find the solution! And if you do please let me know, if I'm lucky your solution could also be mine  

[JSM]

I'm assuming it still doesn't run.  Why is the ignition lock out?  Also have you tested the switch on the back of the lock to make sure that is good?  Wondering if it staying closed even when key is off.   You sure the key is really off? 

The security feature is just a pin that goes into the steering column when the key is removed and steering wheel is turned a certain way.

[Jimmyb]

On 2017-11-07 at 7:22 PM, JSM said:

 

 

49 minutes ago, JSM said:

I'm assuming it still doesn't run.  Why is the ignition lock out?  Also have you tested the switch on the back of the lock to make sure that is good?  Wondering if it staying closed even when key is off.   You sure the key is really off? 

The security feature is just a pin that goes into the steering column when the key is removed and steering wheel is turned a certain way.

No it doesen't.. The ignition lock is out because i don't have the ignition key, the lock has probably been replaced at some point. The switch that was on the back of the lock is still there as you can see on a img that I uploaded earlier, I just removed the lock så i could turn the ignition. So i can turn the switch with anything that goes in.

Oh, so the security is just the steering lock and nothing like a programmed key or anything? In that case i should be in the clear as the locks current placement are on top of the roof

But I do believe that the problem is that both pins in the injector connector has voltage, one of them should be ground. The question is why, I've asked around on a local car forum for someone who knows cars eletric that could pay me a visit, still no luck but I'm keeping you guys updated. Hopefully a solution will come my way soon and I can write down exacly what was wrong and then maybe this thread can help some other guy one day.

[Zed Head]

16 minutes ago, Jimmyb said:

But I do believe that the problem is that both pins in the injector connector has voltage, one of them should be ground.

Actually that is a common cause of wonderment, but, as Captain Obvious pointed out to me many moons ago, is normal, for a parallel circuit.  You're just measuring voltage on the other  pin through one of the other still connected injectors.  The voltage that you're measuring will have its path to ground through the transistor circuit in the ECU.  The grounds are ganged together at the transistor in the ECU.  That's why disconnecting the ECU breaks the parallel circuit.  I think that you can move on from that concern and go to the basics, like spark, and injector opening.

Have you verified spark, and tried to start it with starting fluid?  Starting fluid will tell you that you have spark, and compression, and that all of the important timing events are correct.  If it runs with starting fluid, you can focus on injector opening, or vacuum leaks, or similar.  If it doesn't run with starting fluid then all of those other important timing events are suspect.  It's a simple quick test that will get you much farther ahead than where you are now.  You can usually sit at the engine intake with the can of fluid and keep the engine running for a little while, just to hear how it runs.

 

[JSM]

So you know it will start on fluid and  you know the injectors are firing now, I'd go back and ensure you have pressure.  

I'd suggest if you have another pump, put it at the front of the car directly to the fuel rail from a gas can and then run the return line back to the same gas can to simulate a tank.  Eliminate the entire fuel system.

Put alligator clips on the wires to the pump and hook to the battery directly. 

Have a fire extinguisher by for safety. 

Similar to this:

 

Edited November 15, 2017 by JSM

[Captain Obvious]

15 hours ago, Jimmyb said:

I got voltage on both pins on each injector connector.

If I disconnect the ECU then I got voltage on one out of two pins on each injector connector, just like I believe it’s supposed to be.

As Zed Head mentioned, that is normal behavior. This is what the circuit looks like with the ECU installed:

If you pull the ECU out, it disconnects each injector from the others and you can test them individually.