Crank no start turned starts then dies

Oh and I suspect the ground is probably balled up shielding from inside the cable. At least one or two of the cam pos sensor wires are shielded. Really, OP should replace the cam pos sensor totally with new DENSO to clean that up. And really pore over the crank post sensor harness carefully, untaping it from the harness in case the PO did funky shit in there too.

 

The cam sensor is completely new, those wires are up above its connector. They do sell a connector for that area, but you still just have to splice it in yourself.

Update:
Got my neighbors help, they were incredible. We ran some jumper wires and bypassed the fuel resistor/ relay, and it still did died. So it's not the ecu shutting off the pump. One guy got under the tank while it was running and it sounded like the pump was operating even as the truck died. Eventually after starting it at least a dozen times it started running longer, and eventually it was just running largely normal until we shut it off. We got it warmed up and in open loop. It still did seem like it was struggling for fuel a bit, but she was running! Never drove it though, and then went for a day trip so it sat for 6 hours. Got back and tried to start it up and it really struggled to even fire, eventually sort of starting but then died.

So from our testing it appears:
-The timing signal and everything else electrical up until the fuel relay is working.
-The pump isn't being shut off, or shutting off itself
But the truck still really struggles for what seems to be fuel. It sounds and smells like it.
- Mass air flow reading on the obd was in spec with the fsm
- The fuel trim was very lean, at one point 90+%, though I don't remember if it dropped to a normal level once it was running, I assume it did and will verify tomorrow.
- Has at least 5 gallons of gas in it.

I feel that at least checking the fuel filter may be a next step? Any other suggestions?

 

Understand:

And I think this is included above:

If the ECU doesn’t get a valid signal from the crank position sensor (not solely the cam position sensor), either because its harness has faults, or the sensor is faulty, it IMMEDIATELY shuts the fuel pump off. No fuel, no run.

Im not sure if this bit has registered yet, but it’s why Bubba and I both (I believe) are pushing you toward that. But maybe I missed something above wher you validate the crank pos sensor and its harness.

 

Yes, I understand this. Considering the truck eventually ran for 5+ minutes I'm willing believe it is probably not that. We have determined that the ecu is not telling the fuel pump to turn off, yet the fuel is still not reaching the engine in large enough amounts. Of course, it could be that the times it ran were because the wires got moved/ jiggled and they managed to send out another signal, though I'd think that would lead to an intermittent style of random starting/ dying, not the very linear continuously getting better and running longer that it was able to do until it was fully operational. I would also think it would lead to the fuel pump turning off, which we believe it did not.

I'm not going to completely write it off, that is what I thought it was for a long time. If I don't find anything mechanically related to a fuel blockage, my neighbor offered to use an oscilloscope to look deeper into the electrical side.

 

I guess next Q: have you pulled the ECU and popped it open to look for damage/corrosion inside? This could be a bad ECU situation. Wouldn’t be the first time.

 

Oooh, no I haven't. That does seem like a good step. I will look into that.
I was reading a thread where a member tried almost everything, but didn't have luck until he swapped in a junkyard one, don't remember which thread it was. Hope its not that!

Thank you shifty and bubba, and everyone else!

 

Yeah, we’ve had a couple people here, when they opened the ECU clamshells they found water or similar damage to the corner of the circuit board. Absence of any sign of damage would be inconclusive but … it’s just a thought.