Will not start!!

[ShadowKnows]

2000 Nissan Pathfinder 4x2 (only one engine option)

Truck was running fine, drove down to Houston (~400mi) and drove around town while in Houston. Headed home and stopped for gas ~300mi away from Houston. Got back on the road and about 30mi away from gas station the truck just cut off. It did not choke out or stall trying to run, etc.. it just quit as if I turned off the key. Attempted to restart truck while coasting down the road but nothing. Coasted into small store and when trying to start truck it just turns over - no attempt to fire at all.
Once I got towed home (expensive) I began troubleshooting.
Could not hear fuel pump running when turning the key to the run position, and giving how it died I made the assumption that the fuel pump went out. So I replaced the fuel pump.
Once I could hear the pump, and checked that I had pressure (42psi) it did not change anything as far as starting.
So I began to check all other mechanical aspects.
Have spark to all cylinders.
Have compression to all cylinders.
Distributor rotor turning with no jumping or stopping.
-Still no attempt of motor to fire - just turns over and over.

Once I had run down the battery I decided to disconnect and charge. Slow charge, ~16hrs, full charge and reconnected battery.
Several minutes of priming of fuel system (in the interim fuel line had been opened) the truck started trying to run.
Finally got engine to start, and once it smoothed out I could rev the engine and everything seemed normal.
Let engine run for ~15min while cleaning up tools, and then went out for a test drive.
I could give it gas and lunge forward, felt like normal power.
Got about a mile down the road and stopped at light. When taking off from light it initially accelerated and then began choking out unless I backed off peddle.
Did this for about a minute and then started dying when I gave gas, but could restart and let idle.
I could give it gas as long as I was not in gear (automatic) but died if I tried to move.
Then the engine would no longer start, no attempt to fire and got someone to tow me back to the house.
Now it is just turning over and over not attempting to fire - again.

Thanks in advance for any assistance.

[MisterH]

Have you been able to find out if the ECM threw out any error codes?

[ShadowKnows]

Only what the computer can pickup with the engine not running or held from the last run - which was a knock sensor code (P0325) - and Fuel Temperature Sensor failure (P0180) but I have that assembly removed from the tank atm to drain/dry and replace fuel (..as I cannot think of anything else to do, and to establish a mechanical base-line before anything else).

[Rockwood]

QUOTE:
Got about a mile down the road and stopped at light. When taking off from light it initially accelerated and then began choking out unless I backed off peddle.
Did this for about a minute and then started dying when I gave gas, but could restart and let idle.
I could give it gas as long as I was not in gear (automatic) but died if I tried to move.
END:

That sounds like a MAF going bad to me. You might be able to get it to start and idle by disconnecting the MAF. No guarantees tho. MAFs often fail without tossing codes.

It could be a fuel starvation problem, but you have a new pump. Did you change the fuel filter? A little water stuck in the fuel filter can cause symptoms like that. Try a new filter first if you haven't changed it yet.

Distributors on the 3.3's are pretty common problems, but you have spark, so it seems that is ok.

Never any fun when they die out on the road and you have to get a tow. I have towing coverage on my insurance policy and used it once when my cam position sensor died. Might be a thought if it is not too expensive thru your insurance company.

[ShadowKnows]

Thank you for your assistance.
Regarding the portion you quoted however, that was showing the progression of what happen after the one and only time I got it running again. Therefore as relevant as the quoted portion may be, you left off the last stage of that progression which is that it is now back to its initial failure state - not attempting to start at all, just turns over.
Not aware how the mass air flow could keep the engine from trying to fire as its primary function is to offer monitoring data the computer uses to determine the necessary fuel regulation of a running engine. The computer would expect the MAF to have virtually no reading when starting the engine as there would not be enough airflow under the slow rotation of the starter motor.
However can that sensor just be disconnected or bypassed electronically for troubleshooting purposes?

A little background: A little after high school I worked as a mechanic for a small repair shop, then spent the next four years as a mechanic for a dealership until they shut down (Lawrence Marshall Chevrolet outside Houston) which was simply a continuation of what I had been doing since junior high school - so I have proficient knowledge of engines. However since my career went into the IT field after that (30+yrs ago) I have almost ZERO knowledge/experience with computer controlled engines. To me that is the most frustrating part of this - the awareness that the engine could be mechanically capable of running but some BS combination of sensor/monitor readings would cause the computer to shut down the engine! Truly frustrating as I do not have access to the necessary systems to monitor/control the computer in real-time.
So my troubleshooting methodology starts from [if it was a mechanical naturally aspirated engine] and then add each tier/layer of computer monitored control above that.

With everything mechanically looking ok, the first tier would be the fuel injection system - notably the electronics and associated monitoring that facilitate the injectors.
I do not have any immediate knowledge of the best way to check the circuitry of each injector - specifically the monitoring/regulatory system that could shut them down - and cannot get to the fuel pressure regulator as it sits too far under the intake manifold.

In knowing that a certain pressure is needed to feed the injectors, which the engine appears to have initially, I do not know if that is being maintained once the engine is running.
While I have not tried it yet (empty gas tank from drain&dry) I'm thinking that I should be able to partially or fully pinch off the return line from the rail (after the FPR) to create constant pressure. As the FPR is a mechanical device (vacuum driven spring/diaphragm) it could be giving out under a certain pressure or sticking open - whatever condition would cause pressure to drop below the necessary specification.
1) Will the fuel pump give out or be damaged in some way if there is no bleed off due to the return line being completely pinched off?
2) Should there be any fuel making it past the FPR at all during prime?
I do know that during initial priming (key moved to run position) there is fuel passing through the FPR, albeit at a significantly lower flow than before the rail and FPR. Even without an exact measurement, fuel can be seen as a strong flow before the rail and FPR, versus a moderate trickle on the return line (after the FPR) - both observations from the high side and return side lines under the hood during prime stage (engine not running)
3) What would be the easiest method of checking if the injectors are being shut down?

[MisterH]

I know you said you have spark and fuel is flowing but another possibility is the camshaft position sensor is working intermittently. Unfortunately the fix is the replacement of the distributor.

[Rockwood]

Try disconnecting the MAF first. It will set a code, but the ECM will then use its internal fuel / air tables. So the vehicle should start and idle. You may have problems starting the first time because your plugs may be wet from cranking. Starting fluid may help. That is probably the easiest thing to try first.

If the truck starts and idles with the MAF disconnected, the MAF is very likely the culprit. MAFs fail with all kinds of symptoms. I had one fail on my truck, and it went full rich, to the point where I was fouling plugs. Just barely made it home, then it would no longer start. They will also go lean. Just depends on what goes bad inside the MAF I guess.

The crankshaft position sensor signal is used by the ECM to fire the plugs. Crank sensors often fail without setting a code, even tho they are supposed to.

The camshaft position sensor signal is used to fire the fuel injectors. That is in your distributor. They are pretty good about setting a p0340 when they go bad, but it is possible to have one fail without setting a code.