This probably explains why it runs lean at WOT.

 

Obstruction? Low voltage? Weak pump? FPR?

 

Dunno yet. I dont see anything externally that looks like there would cause an obstruction. I have already been underneath, and it has great flow out of the fuel filter and into a jug. Ill test the fuel rail this week. And wiring, fpr. But I thought it was interesting that right at around 18-20 psi, vroom. If only the TBI pumps had a little more power in them they would at least be able to start up a TPI, barely.

 

I pulled the regulator vacuum and got a jump up above 40. So the pump can handle it.
It also builds pressure quick when the pump has been running for a few minutes after a cold start. So I dont have an experience with bad fuel pumps, possibly that is a symptom - that when the pump is cold, it operates slowly, but when powered for a little while, its finally warm and begins to operate normally.
Sorry for blurry gauge, those are in standard 10 pound increments. The below is when warm. I didnt capture when cold, but at cold, disconnecting the fpr the pressure rose to 40, very slowly. About 1 p a second.

 

I tried it again this morning cold, and there are no issues what so ever. I jumped the relay, and the pressure shot straight to 45. Emptied the gauge, then tried it via turning the key. It also shot up to 45. I cranked it, took a couple of seconds, but it started it and leveled out to 30-35psi, whatever is normal. I don't think I have ever seen pumps act this way before.

 

Could be flaky electrical connection or flaky regulator I guess. Certainly seems like obstruction isn't a problem. No gas coming out of the regulator when left unplugged? Done a voltage drop test on the pump wiring, both power and ground? Of course if it's not showing the symptom anymore that would be annoying to troubleshoot further. Good luck

EDIT: I see you also have an amp clamp so measuring the amp draw during low-PSI and high-PSI conditions would be good.

 

No gas out of the regulator.
Next time I see this happen I can do a drop test. But I noticed that theres a PID for fuel pump voltage. I looked thru all of my old scan logs, and all show good voltage.
lol decent idle at 20 psi