Fuel Pressure stuck at 35 psi?

[guyomatic]

Hello Everyone!

Long story short, tuner was unable to get my new motor running with the 98 LB injectors the shop got from DeatschWerks (twice), so they just kept the 35 lb truck injectors in since I had to break the motor in anyways (I didn't think anything of the 35psi fuel pressure, knowing though the standard is 43 and 58 psi because my AFR was fine, but My redline was basically 3500 RPM as I didn't have enough injector.)
I just installed my new injectors, (Injector Dynamics ID1300x2, about 148lb) and recalibrated the current tune (using the data from Injector Dynamics) and adjusting the spark and VE tables and the car starts, but I'm still at 35 PSI??? Interestingly enough, after the editor reads the PCM and does the 'clean up' and you hear I think the fuel pump, it shoots upto 43.5, then goes back down to 35 PSI. Can anyone help? My tune is attached. thanks!

1971 Camaro
Gen III P59 PCM
6L LS
Twin Magnum 76/56 Turbos (7 lb springs for base tune)
91 pump gas for now..
2 bar MAP
Boost referenced AEM Fuel regulator with return
Meth injection
Magnum Tremec 6sp

[5FDP]

It's going to be something wrong with your pump or regulator if your fuel pressure is still to low. The computer doesn't control fuel pressure.

[guyomatic]

It's going to be something wrong with your pump or regulator if your fuel pressure is still to low. The computer doesn't control fuel pressure.

That maybe true, but when I got the car it had the same setup, but with a 5.3 and 4L80e (I blew rings on a couple cylinders and got a deal on another motor). I was running 43.5 PSI before, same pump and regulator, I was lucky and had a video of the inside of the car before and my fuel pressure gauge was at 43.5 all the time...

[kevin87turbot]

If you have a boost referenced FPR, then you have to set the fuel pressure with the vacuum line disconnected from it. Once you adjust it to 43.5 psi with the vacuum line disconnected, then you'll reconnect the vacuum line. At that point, the manifold vacuum will reduce the fuel pressure. It's certainly possible that it'll drop pressure by 4-7 psi.

[guyomatic]

I do have a bigger cam and less vacuum. I need to check the fuel pressure going into the rail, if it's 43.5 or 58, then I should be okay right (sorry for the basic questions, I'm a newbie)?

[guyomatic]

If you have a boost referenced FPR, then you have to set the fuel pressure with the vacuum line disconnected from it. Once you adjust it to 43.5 psi with the vacuum line disconnected, then you'll reconnect the vacuum line. At that point, the manifold vacuum will reduce the fuel pressure. It's certainly possible that it'll drop pressure by 4-7 psi.

I will try that. thanks!!

[TheMechanic]

Check your dead head pressure to see if the pump is even capable.