It will not start. it turns over and cranks but will not start. fuel pump, silenoid, fuel filter, ignition cylinder and ignition switch internal have all been replaced. The spark plugs are not firing and the fuel pump is not getting power to engage.

Fuel, air, spark, compression, valve stuck, head gasket etc etc etc
Be more specific

What make , model an year vehicle ? You need to explain a little better what's happening ! When you turn the key to the start position what happens ? Does the starter spin the engine ? The engine doesn't start an run ? A crank no start or no-crank no start ? How do you know there is plenty of fuel pressure ? Did you hook - up a fuel pressure gauge ? An how do you know fuel is reach cylinders ? Did you do fuel injector fire test ?

Are you getting power to the ignition module? It could be your ignition switch. I once had a 1993 Buick that would die intermittently with no rhyme or reason. Turned out to be the ignition switch. And my daughter has a 1995 Camaro that when you would start it...sometimes it would be a 2 cylinder, sometimes a 4 cylinder, and other times a 6. Still not sure how that one worked, but it was the ignition switch that is located on top of the steering column down by the firewall.

may need tune up [plugs, air filter , fuel filter ,wires,egr cleaning]these areas would cause problems in starting ,

First check your fuel pressure it should be 41-47 psi with key on and engine off if its below 32 psi replace the fuel pump and filter.If fuel pump checks out to be good then take ignition switch out and check for burned ignition switch wires and worn ignition key tumblers and ignition lock cylinder.These cars are known for faulty ignition switches and ignition lock cylinders.Ignition switch gets to hot then it won't start until it cools off.

First you need to determine whether or not the fuel is getting to the cylinders. If it is, the problem has to do with the ignition side. Assuming that the engine has been running recently, Check for gas smell by removing a spark plug after cranking the engine. If there is no gas odor and the spark plug is not wet, there is a problem with the fuel delivery. Check that the fuel pump runs, you should hear it for a few seconds when the key is first turned on (it's in the fuel tank) just before the engine cranks. If the pump runs, check for pressure at the injector rail - you will need a service manual for some of this. If the fuel is getting to the cylinders, check the ignition coil by pulling one of the spark plug wires mostly off and listen for a distinct snaps as the engine is cranked. If this doesn't lead you to the problem, you'll need someone with proper test equipment to help you. It could be bad electronic ignition, bad cpu, broken wiring, battery low, short somewhere, bad switches, bad fuses, fuel pump shot, fuel filter plugged, out of time due to broken or slipped timing chain, etc. Extremely plugged air intake or exhaust could do it, too, but would more likely cause it to start and then shut-off.

I'm guessing fuel pump is going. Check for 40 PSI pressure with fuel pressure gauge. Check in engine comaprtment.
Section 10-01: Fuel Tank, Filters, Lines and Electric Fuel Pump 1995 Thunderbird, Cougar Workshop Manual
DESCRIPTION AND OPERATION Fuel Pump, Electric The electric fuel pump:

• Is part of the fuel pump module.
• Is located in an internal reservoir in the polyethylene fuel tank (9002) .
• Is mounted with its inlet at the bottom of the reservoir.
• Is designed to increase satisfactory pump operation during extreme vehicle maneuvers and steep climbs with low fuel levels.
• The high-pressure fuel pump module on the 3.8L SFI and 4.6L-2V engines can supply 60 liters (15.9 gal) of fuel per hour at a working pressure of 269.0 kPa (39 psi).
• The fuel pump module on the 3.8L SC SFI engine can supply 125 liters (29.0 gal) at the same rate and pressure.
• The fuel pump module has an internal check valve to maintain pressure in the system after the engine is shut down.
• The fuel pump module also has an internal release valve to provide protection from too much pressure if fuel flow becomes clogged in the fuel filter (9155) , the fuel line is damaged, or other factors.
• Overpressure is limited to 850 kPa (123 psi) and reduced fuel flow will result if the pressure relief valve is activated.
• The fuel pump module is protected at its inlet by a nylon fuel filter element (9365) which filters contaminants which could plug or damage fuel pump components.
• The fuel filter element simultaneously allows passage of small quantities of water which may accumulate within the tank reservoir.
• The electrical system has a fuel pump control relay in the powertrain control module (PCM) (12A650) which provides power to the fuel pump module through an inertia fuel shutoff switch (IFS switch) (9341) that is normally closed.
• The electrical system provides power to the fuel pump module through two relays:
  • Fuel pump power relay.
  • PCM power relay.

The current path depends on operating conditions.

• When the ignition switch (11572) is OFF, contacts of both relays are open.
• When the ignition switch is first turned to RUN, the PCM power relay energizes and closes its contacts.
• Power is sent to the fuel pump relay and a timing device in the powertrain control module .
• The fuel pump module runs through the contacts of the fuel pump relay.
• If ignition switch is not turned to START, the timing device in the powertrain control module will open ground Circuit 57 after about a second.
• Opening the ground circuit deenergizes the fuel pump relay, which opens its contacts and de-energizes the fuel pump.
• The circuitry provides pre-pressurization of the fuel system.
• When the ignition switch is turned to START, the powertrain control module operates the fuel pump relay to provide fuel while cranking.
• After the engine starts and the ignition switch is ON, power to the fuel pump module is again supplied through the fuel pump relay. The powertrain control module senses engine speed and shuts the fuel pump module OFF by opening the ground circuit to the fuel pump relay when the engine stops or is below 120 rpm.

It is quite possible for any sensors to fail but I would like to ask you for checking out the fuel filters first. Check for traces of impurities/ water in the system, if so change filter and clean the tank, the fuel pump also. If the spark is good and the fuel pump seems pumping good, the fuel injection on idle may be faulty due to particles in the fuel system. If you depress and crank there is a possiblility of flooding and resulting in saturation of fuel inthe cyclinder. the engine willnever start them,Open up all the plugs and clean, dry them before fixing crank and smell for good fuel mixture into the cylinders. Check also your compression on all the cylinders. Now you will have an idea of the cylinders, refix the spark plugs and crank without pressing too much. If it starts to life the fault is definetly with the fuel. recheck the fuel distribution, clean and reset. hope this helps you out. Good day

1 Inspect Battery Battery Discharged or Faulty. 2 Inspect Battery Cable Corroded, Broken, Shorted or Poorly Connected Battery Cable. 3 Inspect Fuel Filter Clogged or Dirty Fuel Filter. 3 Inspect Distributor Cap Distributor Cap Cracked or Burned. 5 Inspect Coil - Ignition Faulty Ignition Coil. 6 Inspect Wireset Worn, Damaged or Faulty Spark Plug Wire(s). 7 Inspect Spark Plug Incorrectly Gapped or Fouled Spark Plug(s). 8 Inspect Starter Starter Motor Faulty. 9 Inspect Fuel Pump Low Fuel Pressure. 10 Inspect Solenoid Switch Faulty Starter Solenoid Switch. 11 Inspect Relay - Fuel Pumpat Faulty Fuel Pump Relay. 12 Inspect Fuel Injector Pressure Regulator Faulty Fuel Injector Pressure Regulator. 13 Inspect Ignition Switch Improperly Connected or Faulty Ignition Switch. 14 Inspect Starter Drive Faulty Starter Drive. 15 Inspect Fuel Injector Dirty or Worn Fuel Injectors. 16 Inspect Fuel Pump Strainer Clogged or Dirty Fuel Pump Strainerat. 17 Inspect Engine Control Computer Incorrect Operating Information Being Delivered and Sent From The EEC. 18 Inspect Fuel Tank Fuel Tank Empty. 19 Inspect Carburetor Carburetor Flooded or Faulty Choke. 20 Inspect Distributor Worn, Loose, or Incorrectly Installed Distributor.

are you geting power to the fuel pump?? On some vehicles the electric fuel pump primes when the ignition is switched on to acc (i.e when all the dash lights come on etc) and on other vehicles the fuel pump doesnt start untill you turn the ignition over to the "start" position. Id check the fuel pump was acutally getting power and go from there