My 78 280z is not Able to turn on unless I leave the key on ON for a while then try it. My injectors seem to make a spraying sound for a few seconds everytime I turn the key. That's if I don't leave the key on ON first. Can anybody give me ideas.

Can't really understand what the problem is. Can you be more descriptive?

From the very limited description my first guess is that the fuel pressure is bleeding down when the car is off. Putting the key in the RUN position allows the fuel pump to build pressure. I believe that if you go through the fuel injection bible that can be found in Blue's tech tips (link below), you will find information on that.

I don't have much knowledge about the Z's fuel injection, but I'm pretty sure there is a check valve to maintain pressure when the car is off.

The car will not start if you just turn the key.one day I left it with the key on ON position for a while without turning it then the car started right up. If I do this most times it works.once the car is on it has a strong gas smell until it warms up. I heard the injectors can also be bad by giving to much gas

Now that I think about it, my first guess probably isn't right. IIRC, in the ON position, the fuel pump has power only with oil pressure. I have to stop posting when I get this tired.

I doubt you're hearing the injectors spraying fuel. You might be hearing fuel rush through the lines.

I suspect Steve is right, even though he doesn't think he is -- perhaps if your description is a bit off. When you turn the key to "start," the fuel pump will operate for 5 sec, IIRC. Then it will stop if there's not either oil pressure or alternator voltage. So if that 5 sec is needed to re-charge your fuel rail, I suspect the fuel is leaking down. You can test this by putting a fuel pressure gauge on the fuel rail, probably between the output of the fuel filter and the inlet to the rail. Pressure should hold for at least an hour, practically speaking. If it doesn't, your injectors (including cold start) might be dribbling fuel, or the check valve on your fuel pump might be letting fuel wash back.

Once you get air in the fuel rail (from a bad injector dribble problem), it can take several moments of engine running to eject it, as the bifurcated fuel path can prevent the air bubble from being "burped" out the return line. (The bubble has to be consumed through the injectors on one side of the rail.)

The solution is to replace injectors and replace the check valve.

Another solution that I used is to install a momentary switch (e.g. pushbutton) that feeds +12V to the coil of the fuel pump relay. You can use this switch to prime the fuel rail prior to starting. Now that I've replaced the working components of my EFI, I no longer need to use my primer switch, but I'm still in the habit. I think it makes the start a bit faster.

I guess I might as well replace the injectors now, any way I don't know how long they been there. This guy is selling new nismo 280z injectors for 230 the set.(worth it)?

Well, before you replace injectors, you should make certain you need to. I only guessed at your problem, but without putting a gauge on your fuel rail, it's only a guess. Besides, a leakdown problem could be the check valve too. Although those are becoming NLA, you can buy an inline fuel check valve off of Ebay that will do the job.

Listen to Sarah. Spend some time and a little money to diagnose the problem rather than throw parts at the problem. It's a lot cheaper to do the former.

Also, check out Blue's tech tips. You'll find a copy of the Fuel Injection Bible. I've heard it's a must have for 280Z owners.

Today I took it out the car to drive it after a week no use. I charged the battery and hour earlier to be able to start it. It eventually turn on but about ten min into the drive I went up a steep hill and the car just died. I got it down to the level street and the car would start but died soon after. I eventually killed the battery from turning it so much, so I had someone jump the car and after about 10 turns it eventually it started. I'm replacing the battery because I'm pretty sure after lots of charging and jumpings is not as good anymore.what do you guys think went wrong

It's hard to say, but if your battery will crank your engine after a full charge, I wouldn't replace it.

There are numerous reasons your engine could be running poorly. You could have electrical problems, fuel delivery problems, EFI problems, vacuum leaks, timing issues. Unfortunately none of us would have a clue from the information provided.

Time to break out the FSM, tools, meters and gauges! I'd start out by looking for vacuum leaks and a sticky/frozen breaker plate in your distributor. Most Z's on the road seem to have these problems.

A new clue! - it died while going up a steep hill, but it did run and drive for ten minutes. It either died because the engine was loaded and that made a problem worse, or maybe it is a fuel supply problem.

Did you have a full tank of gas? How far did you go (ten minutes at 55 mph or ten minutes at 15 mph) before you climbed the hill and how far up the hill did you make it? What did it do before it died, did it cough and sputter or did it just quit? Climbing hills takes more gas supply than just cruising.

The better your description the more ideas you'll get back. Just trying to help, you could give more information about how the car actually runs, when it does run.