1981 280zx will not start

[Eric280zx]

Is this the fuel pump check valve?

[JSM]

I'd be more concerned on why your injectors are not firing then dropping fuel pressure. You need to check why. Noid light or extra injector to hold in your hand that you can confirm the circuit is actually working. 

[Dave WM]

don't go replacing the check valve, just clamp off the fuel line where it exits the fuel filter under the hood, right after the pump turns off. If it holds then the injectors and FPR are ok. It does not have to hold forever, mine will some times go over night other times will drop in hours. Its not super critical about the check valve that is not the problem, even if it did not work at all, the only effect would be a couple extra seconds for the fuel pressure to build back up. I mainly wanted to know if you were getting pressure and how long it hold to determine if there is a leak from one of the 7 injectors. Clamping off the fuel line, then the fuel return line, then the cold start valve in that order after each priming of the system can help narrow it down. OR just pulling the injectors all out to observe will do the same. One last place that a leak can come from would be the FPR. pull the vacuum line and see if any gas drips out with the system pressurized.

But please don't start replacing parts without asking about it, again the check valve or lack of check valve is NOT the problem.

 

[Eric280zx]

So i replaced the fuel pump check valve and fuel pressure was still going down so I replaced the whole pump and fuel pressure was going down just a tiny bit at a time. Probably like 3 seconds to drop 1psi. The CSV checked out to be okay after all and only fires when engine is cold. Injectors aren't leaking. The pressure regulator seems to be working too because when I start it without the hose on it, fuel doesn't come out. So could anything else cause it to flood? For tomrrow, I will do the shot gun method and clean all the corrosion, make sure all the grounds and connections are good, see battery connections, and all the electrical stuff. Thanks Dave WM, I wish I was as knowledgeable as you so I could fix this problem asap 

[Dave WM]

don't forget to check the vacuum hose off the FPR, if the diaphragm leaks it will leak out that hose and directly into the manifold. I doubt its the problem since the fuel pressure is holding but still an easy check then move on to the ECU. If the injectors are not leaking (visual check) and the FPR vacuum hose is not leaking (visual check) then about the only thing left to cause flooding is excessive duty cycle of the ECU OR the thermotime is not cutting off after extended cranking (thermo= do not fire over spec temp, Time= do not fire for loner than spec time) the time part is to prevent flooding if you just sit there and crank the engine for ever. Frankly if it does not start in less 3 seconds, something is wrong and needs to be fixed. When its working well it will start in a fraction of a second.

Edited September 29, 2017 by Dave WM

[Dave WM]

did you pull the injectors and see them spraying gas?

the idea here is to make sure

1. sparkplugs are firing in the correct order
2. fuel pressure is correct (EFI must have correct pressure to work right)
3. injectors/ECU are opening and closing based on sensors
4. startup parts operating correct (cold start valve,thermotime,AAR bypass) all of 4 only applies to a cold engine.

I assume you have actually pulled the plugs and confirmed the spark as well as double checked the firing order.

Edited September 29, 2017 by Dave WM

[Zed Head]

You'll have the most success if you run the electrical tests from the EFI Manual.  Post #6.  The old carb'ed car methods of poking and prodding don't really work with the EFI system.

One way to get too much fuel is if the coolant (water) temperature sensor is disconnected.  Pin #14.

Edited September 29, 2017 by Zed Head

[Eric280zx]

Hey, I apologize for my lack of response. I was unaware of the second page feature and thought you guys gave up on me for my basic understanding of this issue I'm having. Anyway, I believe I might've skipped the step of having the engine centered at number 1 but is that just having the correct firing order? Also, are the injectors supposed to spray when cranking it? Could it be a fuel pump relay, a fuse? 

[Eric280zx]

So I read the injectors should pray and that they get their power from the distributor so could I have s bad distributor system?

[JSM]

Thank you for your simple mistake. Makes me feel normal. 

You need to see if the injectors are opening and closing. You can get a noid light test system from Autozone (borrow), try and listen for them to open , or remove the injector clip and put a working Injector there and crank to check. 

Have you read the FSM yet. There are tons of test in the ECCS section. 

Edited October 2, 2017 by JSM

[Zed Head]

11 hours ago, Eric280zx said:

So I read the injectors should pray and that they get their power from the distributor so could I have s bad distributor system?

You can test the ignition system very easily, just by checking for spark.  You can get a good idea of cam and ignition timing by using starting fluid to start the engine.

Devise a way to test each system independently.  If the engine is flooding, disconnect power to the fuel pump so it won't flood.  Start the engine using starting fluid.  If it runs well with starting fluid then you'll know that timing is correct, so you won't have to worry about that anymore.

You're doing too many things at the same time.