[Rydog2SS]

Originally Posted by Megahurtz

The angle shouldn't be 130 degrees at low RPM. That means the pump is using maximum effort to maintain pressure.

What cam lobe are you using? Is there a lash cap? Was preload checked when installing the LT4 HPFP? Do you have the stock check valve installed on the low side line still? I've seen where the check valve fails a certain way and starves the HPFP, but I have only seen it at high RPM...not at idle....but perhaps its possible?

130 degrees at WOT means the car is out of fuel, but it shouldn't need 130 degrees at idle to maintain pressure.

I would remove the HPFP and inspect for damage and see if you can borrow another LT4 pump to test with.

it's a BTR STG 3 with a 32% lobe, no lash cap, should I have one? hasn't been one on there since 2021 but that doesn't mean it doesn't need one...

Preload is good, I pulled the pump last night and put it back together, everything on the pump looked good, I pulled the sensor/valve piece on the back and inspected it, it looks good.

It is the stock check valve, I am not sure exactly where it is located to be honest, so I will have to still investigate that and will see if it has failed possibly.

The struggling at idle is what I thought was so weird too and then fluctuates under minor loads and under moderate load, the duration will return to what i would expect is normal and the injectors and rail pressure look good, then as soon as i let off and it is headed back to idle or if I make it WOT or close to it, it goes back to 130*, rail pressure drops off and injectors start working harder. the injectors will be at 2 - 2.5ms at idle...

I do not have my scanning computer with me right now, when I get home, I will take some snapshots of the idle, moderate and WOT and post those.

yeah, the big thing is, I don't want to spend 1K on a HPFP and that not be it...

Thank you for the help!