Here's a little bit of background, first off, the truck has been in the family straight out of the factory.. My grandpa worked for Ford and never purchased a vehicle from any other company.

Without getting too long on the spiel, my father has become very attached to it as kind of a keepsake thing, and even though it has nearly 210K miles on it, he refuses to get rid of it, which leaves us to try and repair it.

My brother was driving it and apparently it lost all power and shut off(he had to have it towed home).

Since then it's been sitting in our garage.

The car cranks, but does not turn over, and occasionally backfires through the throttle body.

We've replaced the coilpack, and the crankshaft or camshaft sensor(I can't really remember, will check if needed as the box is still in the car).

I haven't run a compression test yet, but my guess is as there is no antifreeze/water in the oil that we are OK on that front, also, the car is cranking and almost sounds as if it wants to start, so I assume that the timing chain hasn't 'broken', though the timing may be off.

We tried the starter fluid in the throttle body trick, and the car will still not start, which made us assume it was a spark issue, so we replaced the coilpack.

Since then I've purchased a spark plug tester and compression tester(was having issues with my car which I have now fixed so I'm moving on to his).

It seems to be getting fuel to the rail, it sprays out of the little air nozzle, though I don't have a fuel pressure tester.

Any more information needed just let me know... I really wanna get this truck working for my dad so we can sell his P.O.S. Land Rover.

 

You got a spark tester but never said what the result was on the 4.0l?

Compression
spark
fuel

That's what you need

If engine sounds "normal" when cranking then compression will be assumed OK.
Starting fluid in the intake will fire even with low compression.
So my guess would be spark.

But your fuel pressure needs to be 65psi, and a sudden loss of power and stall could be a fuel pump issue.

When you turn on the key the computer will run the fuel pump for 2 seconds to prime the fuel system, listen for that.
If you don't hear it then Fuel Pump Relay could be bad or fuel pump fuse could be bad, both are located in engine bay Fuse box.

If you do hear the pump come on, turn key on count to 3, turn key off, repeat 3 times then try to start engine.
If check valve in fuel pump is bad system will lose pressure, priming the system a few times should build it up.

The CKP(crank position) sensor is the one that tells computer you are trying to start the engine, computer then turns on the spark and the fuel injectors, so that is an important sensor, but these rarely fail.

CPS(cam position sensor) times the fuel injectors and plays a part in advanced spark timing but engine will still start and run without this sensor working.

 

Sorry for the delayed response, and thank you for trying to help.

Car has spark(on all 6 cylinders) and yet it doesn't try and start with starter fluid in the throttle body.

My assumption with just a small amount of knowledge of cars is timing, but to my understanding the 4.0 has 3 timing chains, and I really don't want to get into messing with those if that is the case.

And yes, the car does sound normal when cranking.

 

Timing chains are an issue with the 4.0l SOHC, but they tend to make noise, noticeable noise, before there would be a no start issue.

Timing chains do the valve timing, not spark or fuel, so if cranking sounds normal then timing chain(s) wouldn't be the issue.
You would get a loping or stopping when cranking.

Spark and fuel, on startup, are "timed" by the CKP(crankshaft position) sensor.
It is behind the crankshaft pulley.
On the crankshaft there is a toothed wheel, the sensor "sees" this wheel, the wheel has a marker for #1 cylinder being at TDC(a wider tooth).

When you crank the engine the CKP sensor sends pulses as each tooth passes, longer pulse for TDC, when the computer sees these pulses it starts the spark(coil) and the fuel(opens injectors).

If CKP sensor dies engine dies.
If you have spark CKP sensor is working.

BUT..............is the spark coming at the right time?

Start Fluid(ether) has very low combustion temperature, which is why it is a good starting fluid.
It is very puzzling to have spark but no "fire" with ether.


I guess best thing now would be to do a compression test on at least 2 cylinder.
Would expect above 150psi

And borrow an old stye timing light, connect it to #1 spark plug wire and point it at timing mark on crankshaft pulley, crank engine, see if spark for #1 is coming at TDC mark.

 

back fire through intake IMO sounds like a timing issue

 

Finally got a scan on the truck, it had two PATS codes. Cleared those still would not spark, pulled computer and turns out it's fried, although no damage is visible the board itself smells like smoke. My next question is that in the beginning of all this I had a suspected bad cylinder, I pulled plugs off coil pack one at a time to determine bad which one was dead. Could a spark could have went back to computer and caused the damage?
​​​​​​. Also what suggestions can I get for new ECU ? Will remanufactured work/ junkyard salvage ? And will my Pat's have to be programmed to computer as well ?

 

The transistors in the computer that control the coil/spark could in theory be damaged by external testing but it would be an extreme long shot, never heard of that happening

Never replaced a computer on a 2004 so just speculating here.
You can get used 2004 4.0l SOHC computer(PCM) with PATS keys and hopefully they can be re-cut to fit your doors/ignition

refurbished or new PCM can often be ordered without PATS or with 2 new blank PATS keys programmed in to PCM, than can be cut to fit your doors/ignition