My 280Z cranks but doesn't stay running once started

[K Koehn]

Hello, Im new to this forum, I have a 1975 280Z 4 speed which will crank and start but only for a second or 2, if I apply any throttle, it just immediately dies, and sometimes to keep it running, I have to hold the key to make it run longer until it just eventually dies anyway,  Ive put in a new rust free fuel tank, all new rubber fuel hoses from rear to front, new fuel pump,  blew compressed air through all of the steel lines including the fuel rail, replaced injectors with new ones, new fuel pressure regulator, new fuel filters (one in engine bay and one in line next to the fuel tank and fuel pump), new battery, new cold start injector, new thermotime/water temp sensor, new water pump, new fan clutch, new NGK spark plugs,new fuel injection relay, new ignition coil, new air filter, fresh oil and gas, all new vapor hoses, new ECU, Ive checked for binding in the AFM's flap, no binding, and it triggers the injectors and pump, Ive cleaned the AFM's fuel pump contact points, and can confirm the fuel pump is getting power, I disconnected the starter to see if I could hear it at crank, and the pump hums when cranked, and the injectors spray as well, and the pump is getting full power at its connections, I disconnected a fuel hose while someone cranked it and it has fuel pressure, the car can start several times but just keep dying, and even more so if I even touch my throttle ,and its not draining my battery much, stays at 12-13 volts even with it dying out. Something else is just killing it, Im just not sure what in the world it could be, im not good at wiring, and im fairly new to working on cars all around too, 4 years at most, I also have an FSM but just can't figure it out, I could really use some help, needing it fixed badly. I also haven't replaced my fusible links, alternator, starter, distributor, distributor cap, spark plug wires, or voltage regulator

Edited January 24, 2019 by K Koehn

[siteunseen]

Make sure the vane isn't stuck behind the black box on the afm. Try tapping it first if it hasn't been off before. 

Are the distributor cap contacts worn down? New cap and button would be money well spent.

Have you tried turning the distributor to advance timing when it's running?

Guesses...

[K Koehn]

I actually don't know how to tell if the points are bad, I took a few pictures of the bottom of the cap and the rotor. I also have no idea how to set it to advanced timing too, its my first car, im really new to it, and here's a picture if you can tell it looks stuck on the AFM, I tried moving it a little and nothing seems to look stuck

[Zed Head]

1 hour ago, K Koehn said:

Hello, Im new to this forum, I have a 1975 280Z 4 speed which will crank and start but only for a second or 2, if I apply any throttle, it just immediately dies,

lew compressed air through all of the steel lines including the fuel rail, replaced injectors with new ones, new fuel pressure regulator, new fuel filters (one in engine bay and one in line next to the fuel tank and fuel pump),

 I disconnected the starter to see if I could hear it at crank, and the pump hums when cranked, and the injectors spray as well, and the pump is getting full power at its connections, I disconnected a fuel hose while someone cranked it and it has fuel pressure, the car can start several times but just keep dying, and even more so if I even touch my throttle 

Kind of sounds like low fuel pressure.  Could be that you have a blockage at one of your filters.  Get a gauge and see what pressure it has when it dies.  You'll get spraying at 5 psi but that's not enough flow to keep the engine running.

You need to know the number.

[rcb280z]

His timing is maxed out looks like.

Why are you running a points distributor? Just curious.

[K Koehn]

That distributor just what came with the car when I bought it, I never put it in or anything.

Edited January 25, 2019 by K Koehn

[Dave WM]

can you hear the fuel injectors clicking while cranking (listen with a mech stethoscope)? are the plugs wet or dry after attempting to start? Just wondering since someone has been messing with the ignition (should not be points) perhaps the ECU is not getting the signal to fire the injectors.

[K Koehn]

I hear a spray coming from the fuel rail area, I figured that was the injectors firing in there.  I had no idea my 280 wasn't supposed to have points, what should my car have? I could use some help on that, ill also have a look at the spark plugs and ill listen in on the injectors 

Edited January 25, 2019 by K Koehn

[Zed Head]

1 hour ago, K Koehn said:

I hear a spray coming from the fuel rail area, I figured that was the injectors firing in there.  

That was probably just the fuel pressure regulator hissing.  The injectors don't spray constantly, they open then close.  Click, click, click.

Does the tachometer work?  The computer uses the same "signal" to fire the injectors.  Points should do the job since the signal comes from the negative post of the coil.  But the blue wire has to be connected to Pin 1.

[Dave WM]

1 hour ago, K Koehn said:

I hear a spray coming from the fuel rail area, I figured that was the injectors firing in there.  I had no idea my 280 wasn't supposed to have points, what should my car have? I could use some help on that, ill also have a look at the spark plugs and ill listen in on the injectors 

it should have a distributor with a reluctor and some electromagnet coils (1 or 2 depending on if its a cali car on not). there should be a ignition module on the passenger side up by the fuse box in the foot well area. The points should work to fire the ignition coil, just prob not as hot a spark and more maintenance, but certainly fine for the job, cars used points for decades. Prob the PO just did not understand the ign module, or it was bad, or the distributor was bad or they just liked points. The key is the ECU needs a signal, as mentioned by ZH just need to make sure its hooked up. I assume the car ran at one time with that setup, but assumptions can get you in trouble.

Put the stethoscope probe right on the injector, you will here it clicking away if its working. If you have good ears you may hear it without the stethoscope, or just get some hose about 2ft long and hold that to your ear, with the other end up next to the injector.

Edited January 25, 2019 by Dave WM

[rcb280z]

How long have you had this Z?

Do you know if they installed the correct cap and rotor considering its a points dizzy? IIRC the 70-73 cap and rotor are different from the other years.

Do you know how to adjust and clean points?

Like mentioned above, check spark (looking for strong spark), fuel pressure and if the injectors are firing. Fast clicking sound will be heard.

Look at the spark plugs. They tell you a lot. Not sure then take pics and post.

Edited January 25, 2019 by rcb280z

[Zed Head]

6 hours ago, K Koehn said:

 which will crank and start but only for a second or 2, if I apply any throttle, it just immediately dies, and sometimes to keep it running, I have to hold the key to make it run longer until it just eventually dies anyway, 

the car can start several times but just keep dying, and even more so if I even touch my throttle ,and its not draining my battery much, stays at 12-13 volts even with it dying out.

It runs.  So it has spark.  Sounds like it's starting on the cold start valve but not getting injection from the injectors.  If he holds the key to Start that keeps the cold start valve open.  Until the thermotime switch heats up like it's supposed to.  At least the CSV system works.

Best get to the Downloads area and download the EFI Guide Book and the 1975 FSM.  Then get a meter and do some testing.  You're close.