My 2001 nissan altima turns over but won't start. I had the fuel pump replaced about 3 months ago. I've also replaced the fuel filter, but it still won't start. Do I have a major problem or is this something I can fix myself?

Have you checked to see if it is getting spark if it is getting spark but intermittently please read the following: remove the distributor cap and check the ignition rotor sometimes the set screws will back themselves out and cause it not to start.

It takes fuel, air, spark and compression to make any combustion engine run. If I were you, and I thought it was indeed the fuel pump or fuel filter I would take the fuel line off after the filter and turn the key on. If no gas comes out.. then it's the fuel pump or filter. If it does then its either air or spark. Check your ignition. By pulling off the coil wire and putting a small screwdriver inside, lay the screwdriver down on a piece of metal and turning the key. If you see a spark then it has to be air. If not then it is the ignition system. If there is indeed spark then it has to be either air or vacuum. This is the easiest step. Take the air box off and see isf it starts

Here's a new one. I have 2 sets of keys to my 2001 Nissan Altima. One set of keys would not start the car, the car turns over but won't start. The other set of keys will start the car fine.

I replaced the battery in the faulty set of keys, but same results. The key fob will lock and unlock the car, the key will make the engine turn over, but it will not start. If I use the other set of keys, the car starts fine.?

Each ignition key needs to be registered with the on-vehicle Nissan Vehicle Immobilizer System (NATS) before the theft system will allow start up.
See your dealer for further assistance.

Hmmm, wonder how this set of keys got 'unregistered' in the first place! It was one of the 2 original sets that came with the car when it was brand-new.

I guess a trip to the dealer is in order. Rats!
Thanks for your very helpful response -- at least I know what to do.

Please don't go ask them to re-register the keys until they have verified the fault and re-registering the keys will fix the problem. Ya know what I mean?
My recommendations are simply based upon your symptoms where as the dealer can do a hands-on diagnosis and then tell you exactly what your car needs. It may cost a little more paying for the diag but at least it will be fixed.
Let us know...

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Originally Posted by jlfiller

Hmmm, wonder how this set of keys got 'unregistered' in the first place! It was one of the 2 original sets that came with the car when it was brand-new.

I guess a trip to the dealer is in order. rats!
thanks for your very helpful response -- at least I know what to do.

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The engine will rotate but we are not getting a spark?

2000 nissan altima runs fine but won't run unless you spray fuel in the intake .
Changed the injector fuel pump plug wires fuel regulator any help would be appreciated

natethatsme, check for any codes and pending codes with a scan tool. With that said, Altimas are notorious for Camshaft Position Sensors and Crankshaft Position Sensors failing. The same sensor is used in both applications. It goes without saying, check all under hood and under dash fuses with a test light or multimeter.

Figured out tonight that after 4 min of spraying fuel into the intake that the injectors not get a signal from I guess the computer or ecu after 4 min of spraying fuel the injector or the signal that I need starts to work... so the question of the week is finding out what sends or controls the ground that is introduce to the injetors...