So I done goofed. A few months ago I bought a new battery for my 280zx and I accidentally crossed the terminals. The result was the black fusible link that goes to the EFI burned out. I was kind of in a hurry, and I didn't immediately notice the burning smell so I tried to start the car after getting the terminals right. It of course, didn't start.

So that was the initial problem. The ECM is still good according to the green light check. I've listed my tribulations as they happened in the second post if you care to hear them, but I'll just put here what I replaced and when I tried to start the engine again in chronological order.

-replaced fusible link and fuel injectors. wouldn't start, liquid fuel was observed leaking from the exhaust manifold
-replaced spark plugs, spark plug wires, distributor cap (there was considerable corrosion). wouldn't start
-replaced ignition coil. wouldn't start

At this point I tried using starter fluid and it started, but died after a second or two.

-replaced fuel filter. wouldn't start
-replaced fuel pump. wouldn't start

Today I replaced the fuel pump and it's obvious that it didn't work. However I noticed that the first time I turned the car on after installing the new fuel pump, I could barely hear the pump working, and I was listening for it. When I tried to start it, it turned over much stronger and it *almost* started, but never quite got there. By the third attempt to start the engine I was able to hear the fuel pump initializing very clearly. It was much louder.

I'm thinking that somewhere there's a blockage and it's creating too much pressure for the pump to work smoothly. The car has been sitting since late December, and I know gas will gunk up over time, so I think there might be something to this theory. Tomorrow I plan on checking the fuel flow at various points and try to find where the blockage is, if there is one.

A respected source told me to check my ground wires. He said he had a 240z that was doing the same thing as mine and it turned out that a ground wire had melted. He said when he replaced the wire it started strong and never gave him another problem.

I'm running out of ideas here, so any and all input will be GREATLY appreciated.

 

The long version:

My first response to fixing it was to replace the fusible link and the fuel injectors, as well as any hoses and hose clamps I ran into along the way (the car really needed it). Once I got it all hooked up and sealed (I found out that I didn't tighten several of the hose clamps enough) I tried to start it. It cranked but didn't turn over.

I knew the fuel injectors were working because there was liquid gas coming from the lack of a seal in the exhaust manifold (the studs are rusted through and is currently being held on by vice grips). I also checked for the green light from the ECM behind the driver's side kick panel and it was good.

I assumed that the problem must therefore be that the spark plugs aren't firing. I ended up replacing the spark plugs, spark plug wires, and distributor cap. The car cranked but didn't turn over. Then I replaced the ignition coil. Again, it cranked but didn't turn over.

I got some starter fluid and sprayed it into the air intake and it started, but died after a second or two. So the problem was the engine wasn't getting fuel again. This was when I noticed that when I tried to start it that fuel wasn't leaking out of the exhaust manifold like it was before. I have no idea if this is significant. Then I tried replacing the fuel filter. Nothing changed.

Today I replaced the fuel pump.

 

i did the same thing. my ecu fried, but i got a new one. the new one's light turns on, like it should, but it is sending too weak of a signal to allow the injectors to pulse. now just to be clear, they are getting the signal, but the ground is too weak. perhaps you should look into that?

 

Yep. That was it exactly. I just got the new/used ECU today. Plugged it in and it started right up and I drove it around.

If it's been sitting for five months is it normal for the idle to be about 550? I noticed it started at about 400 but has increased to 550 in about an hour of driving.

 

I am assuming you're driving an n/a?

If it is running completely fine aside from the idle, I'd check the timing, TPS, and then adjust the idle screw.

 

Yeah mine's n/a. Before the changes, it ran fine. Now the idle's low and it's slow on the pick up when I accelerate. I'm thinking a cylinder isn't firing. I'm finishing up finals right now but when I'm done I'll check the spark plugs.

Also there's a hose crimped that leads into the air intake. And it does seem to be running rich because of the detonation in the exhaust and engine. And I either can't find the idle adjust screw or it didn't do anything.

 

What hose? The vacuum line that hooks up to the intake manifold?

I still say you should definitely check the timing and make sure the distributor didn't get moved. Or something else could have changed..

When you get the chance try pulling the spark plugs to be sure all of the cylinders are firing.

Also, the idle adjust screw is just a big screw sitting on/next to the throttle body. I don't have an n/a so I don't have a picture of it but you should get a Haynes manual. Here is a quick screenshot from the FSM (probably not the best one in there but I just saw it when I was going through).

 

I attached a pic of the hose I mentioned. My last final is tomorrow so I should be able to get in there sunday.

Also easily visible is one of the vice grips currently holding the exhaust manifold on. I've got rusted studs.

 

Quick update: I got a chance to get under the hood today and checked the spark plugs. They're all firing but the gaps were all too short 34 instead of 44... It wasn't me, I swear! And I got a new hose to fix the one that was crimped, so there's no hindrance on the air flow due to that.

Now the idle is a little better because it's not missing but it's still low, around 550. I forgot to mention before that if I'm driving and I let off the accelerator, the rpm's drop down to about 250 and will sometimes even kill the engine. The last time I had a car do this it ended up being a loose air filter on the carburetor, which would tilt and let too much air in and kill it.

But with I'm still getting some detonation in the tail pipe and it's still slow on the uptake. So I'm going to eat real quick then try and play with the timing.

EDIT: Also, I was reading up on the FSM about the idle control, and it said that there is no idle adjust screw because the idle is controlled by a feedback system. One of the inputs is vacuum, so I think I'm going to test for that too.

 

Closure:

It was a bad fuel injector. I replaced it with a new one and it runs like a dream now.