I killed the battery in my '78 280Z, and recharged it fully, but the car cranks and does not fire now...help please?

 

Could be a couple of things, depending on how did you kill the battery? If it was through cranking but you were out of gas, then if you added gas you may have some air locked into the fuel line(s), no fuel getting to your injectors. Can't hurt to pull a plug and see what it looks like (maybe fouled somehow...) and while you're at it you can see if power is getting to the plug by having another person crank the starter, you hold the plug wire *by the insulation* and seeing if it arcs to the block (warning: if you have old wires and are touching the car on this test, you might get a zap, so use your judgement). No arc, no spark. Lastly, if you killed the battery because the alternator died, then there's a fun piece of info on the 280Z fuel/electrical system. If the alternator isn't creating charge, there's a relay on it that shuts down the fuel pump (this apparently is a safety feature). It will pump while the key is on Start (bypasses that relay), and then shuts down when you go to On (now using the bad relay), fuel pressure drops so quickly that the car won't start. A fuel pressure gauge after the filter and before the rail can help diagnose this. For me, it was indeed this kind of a dead alternator, and they're fortunately really easy to replace. If that sounds suspicious right off to you, you may want to remove the alternator and just get it tested (good parts stores can do that for you). My experience is the alternators tend to die staged and intermittent deaths. The most recent one that went on me let me start the car cold and drive whereever I wanted to. But, then it was warm enough that it wouldn't REstart (electrical temp sensitivity...). Then I could crank as much as I wanted and it wouldn't start. Finally the alternator completely failed, cold or warm, and made it's problems more evident. Hopefully this can save you some of that aggravation. Good luck and let us all know what it really turns out to be!
Dave