Jumpered the pins, same outcome. I have previously replaced both pumps and the fuel filter, so I would like to think those are a solid constant here. When I got it only one fuel pump was working intermittently. It did burn up a fuel pump relay before I swapped the pumps, but I had an extra fuel pump relay and it has seemed okay thus far.

ajs:

Barring a problem with the ECU itself, the symptoms, taken all together suggest a mechanical problem rather than an electrical one. The fuel system can be viewed as composed of two components: fuel supply, and fuel metering.
The supply component includes the tank, hose to the fuel pumps, pumps, accumulator, filter, piping from filter to the fuel distributor, the pressure regulator, and the return piping.
The metering component includes the fuel distributor & air flow meter, the injection valves & lines, and the ECU & EHA.

Things are getting a bit obscure here, but an extended fuel flow test with the pump relay jumpered (10-15 mins.?) might reveal a time dependent fault in the supply. A battery charger hooked up may be required to keep the pumps running.
Have you run with the pressure regulator leak line disconnected?

I will give the extended fuel test a go and monitor it to see if it gets weird after some time. I have not run with the return line off. I will try that first with the return in a clear jug or something.

In the event that I was not clear, I was referring to the small push-on vent line on the fuel pressure regulator, not the return line to the tank.

Ohh got it. Yes I’ve run with it connected and disconnected, doesn’t seem to change anything. Here’s another video of what it does just in case your eyes see anything like don’t (or ears for that matter). https://youtube.com/shorts/QVd2GtiCe5Y?feature=share

i had a ce300 act like that, it was the eha, once warm bogged, lack of power , when cold ran ok untill it started to warm up, eha is suspect with your description

I’ve got a few spare on my workbench, I’ll give one I believe is a good one a go, and report back. Will probably do the extended flow test suggested by Frank while in the area. Appreciate all the thoughts so far!

Alright swapped to my known good EHA, and the car acted about the same. It almost seemed as if it was happening sooner than normal, but still the same symptoms. Also preformed flow test, happily flowed fuel for about 10 minutes. I took a look in the ECU to see if anything looked off. Nothing obvious, some brown looking staining on some of the pins that connect the top portion of the pcb to the lower pcb
https://drive.google.com/file/d/1tIh...YtZ8jmWCNCRQU2