Fueling Troubles

[Moyota]

Hi folks! I've got a 617 turbo in a Hilux that I am very excited to drive.... except it won't go!

I bought someone else's project so I didn't do all the work. But it's clean and I went over it a couple times.

It has: a new tank, new fuel lines, remote fuel filter, and no visible leaks, even when pressurized with a 10psi electric lift pump.

Symptoms:

It idles all day until the second I try to drive it. Then it falls on it's face within 1/2 second of depressing the pedal. If I let off quickly and hit neutral, I can avoid a full stall by mashing the pedal down. For about another 60 seconds as it runs out of fuel, intermittently huffing and puffing. Then it hard stalls.

I believe this to be the IP air locking. It will restart and immediately restall after. But if I push the primer I can feel it's lost prime in the fuel system. It doesn't have that same resistance or sound. I just don't know why...

I have the vacuum kill operational but removed it for a few cycles just in case. Same issues persist.

Repairs Attempted

I replaced my hand primer. Cheap and easy. Didn't work though!

I also added an electric lift pump rated for 10psi to push fuel through the filter and up to the mech lift pump and IP. Everyone says this is wholly unnecessary. But it gave me a chance to confirm that no leaks appeared with lines lightly pressurized.

Diagnosis (Unlikely)

I have three loose guesses... first and worst is that the IP is trash. The engine sat for 9 years before the PO had it running. I'm hoping that isn't the case.

Second guess is that air is being sucked in by the mechanical lift pump. This would happen more slowly at idle and speed up under load/revving. Eventually the air pocket gets big enough it causes the engine to stall.

Third guess is from a guy on FB - He suspects I have a fuel line is collapsing under the vacuum and fuel starving the engine. I kind of doubt this after adding the electric inline lift pump between the tank and filter.

Help!?

So what can a fella do besides adding clear lines and watching for bubbles!?

No, seriously. I'd love a few diagnostic suggestions from those more skilled than I.

[dieselbenz1]

Put the return line into the bottom of a bottle. Start the engine if air is entering the system it will show up as bubbles.