After a few weeks after replacing both fuel pumps, i started having problems with my headlights and a/c not working. Then I'd hear a clicking noise and the would come on. Then one day it just wouldnt crank. I ran the battery down quick trying to start it. 2 weeks go by and i get a new battery. car wouldnt start on first few attempts. Then we heard the clicking noise under dash, or hood, (?) and it cranked. But soon after, stopped cranking again

SOUNDS LIKE A BAD STARTER.MOST ARE REBILT AND YOU CAN GET A BAD ONE.TAKE THE STARTER OUT AND BENCH TEST IT.

That should be enough gas. Maybe the fuel pump is not working. Turn the key to on- you should hear the buzz or whine of the pump iin the gas tank for about 2 seconds. It should turn on briefly to pressurize the fuel line and then shut off until the car is cranked over. If you don't hear anything from the rear when turning the key to on, the pump may have quit working or power is not getting to it. Occasionally, a pump will still work but not well enough to make sufficient pressure for the fuel injectors to work. To check that, the pressure would have to be tested.
So, listen for the pump. If good, check your ignition by checking for spark at a sparkplug. If no spark, the ignition system will have to be checked and tests run to find the problem. If you have spark and still no go, test the fuel pressure. If pressure is low, replace the fuel filter and re-test.

ok first question where did you buy the fuel pump tell me other try this when car is not starting go to fuel pump get a circuit tester have somebody else turn key to on position for ten seconds turn off then again if no noise from pump check for power at fuel pump there should be one wire that has power for obout ten seconds then cuts of. if power to pump and it does the ten second on and shuts of by it self then you got a faulty pump, now if no power at all on ten second teste then get a long wire thay can reach from battery to fuel pump hook up to your battery go to wire at fuel pump and hit it with wire from battery if you can hear pump going on them you have a bad contact ether at fuel pump conector or at relay conector or bad wire one thing when looking at conector at fuel pump you will find sevral wires two wires are for fuel level one power on ground other wires are for pump one ground and other for power to pump if any question ask me i will help i am a mechanic let me know

fuel injected cars cannot vapor lock, so not the issue, when they replaced the fuel tank did they replace fuel pump? It should have been, but 2 things come to mind, they pinched wires when putting tank in and it shorts sporadically shutting off pump, look around with light and trace wires looking for any breaks in plastic coating, or fuel pump is failing.

when you turn the key can you hear the fuel pump hum just before you start. Immobilisers and knock sensors will disable a fuel pump. It could just be a faulty pump. Some knock sensors can be reset others have to be changed.

If you can here the fuel pump then look to your HT leads, distributor cap and plugs, in that order. It's most likely the HT leads

I had the same problem with my 1996 tahoe and it wound up that the fuel pump was going bad and then finally did go out completely. make sure you get an a/c delco or delphi fuel pump as they are much better than the cheaper aftermarket brands that fail after about 1 year or so. also, make sure they check the fuel pump relay located under your hood on the driver's side in the main fuse box. its about 10 bucks or so and also will cause your truck to die and not start again. it's well worth the investment to just replace it when doing the fuel pump. lastly, make sure they install a new wiring harned from the fuel pump in your gas tank to the electrical connector running to the engine. hopes this helps.

My first thought would be: If you repaired an emissions hose, take the car back to Auto Zone (or another parts supplier) and let them tell you what code comes up now. You eliminated one problem, now you have to find another.
I wouldn't do a fuel pump without more information.
Gary

Did you replace th fuel filter ??

You say it won't turn over. Then your problem is with the battery, ignition switch, or starter. If you hear a click, click, click, then the battery is dead. If you hear nothing then it may be a bad ignition switch. Turn on the headlights and then attempt to start the engine. If you hear a click, the lights dim, and it will not turn over, the starter is suspect. Check the voltage at the battery with a voltmeter set to DC voltage on the 20 volt scale. These are the readings you look for. If your battery is not reading at least 12.2 volts it needs charging or replacement. If the battery is over 3 years old, it more than likely needs replacing. Now if I am missing what you are saying and the engine does turn over but will not start then turn on the ignition without trying to start the engine. You should hear the fuel pump run for a few seconds and then shut down. If you do not, then the fuse may be blown or the fuel pump relay may be defective. The fuel pump itself may also be bad. You may have to open the fuel filler door and remove the cap and listen at that location while someone else turns on the ignition in order to hear the pump running.

with new fuel pump and filter, I would suggest looking at the electronic ignition.. sometimes when they go "bad" they work sometimes and don't at other times.. frustrating for sure..