Hey guys, I recently made a post regarding some fuel pressure issues I've been dealing with lately. In my last post, I noted that, with KOEO, my pressure would spike up to the normal 40 but quickly decay down to 30 and slowly creep towards 18-20psi in a matter of just a few minutes. However, I recently ran some fuel cleaner through the system and it seems (?) to have affected the loss of priming pressure. Now, when I prime the fuel system, it seems to hold at a steady 40psi for a solid amount of time, although it still slowly leaks through the course of a few hours. The only thing that has really been concerning me is that, when I turn the engine on, the pressure only holds at a steady 30psi. I've checked the vacuum line leading up to the FPR, and it seems to be dry and operating well, and I've ohmed out the resistors and they're all within negligible range. Im currently waiting on my replacement pump to arrive, just to see if my old Delphi unit is to blame. Does anyone have any insight on why I am losing pressure while the car is running? I'm assuming its either the injectors leaking once the car is turned on or just that the fuel pump I have isn't providing enough flow to the system, or maybe the filter is creating a sort of restriction if its clogged up. Thanks

 

It is fine, when the engine runs at idle the fuel pressure is reduced by the fuel pressure regulator based on engine vacuum. While the engine is idling disconnect the vacuum line to the regulator and it should jump to around 40 psi. System is fine if that happens.

 

Ive read other forum posts regarding the idle fuel pressure, and a lot of posts say that ideal idle pressure for an LT1 is anywhere between 38-42psi. Sorry, I didnt really specify model year in my post, but its a 96. Ive also tested out pressures with the vacuum line leading to the FPR off, and it does indeed spike up to 40psi ar idle. Maybe someone can provide a bit more clarity on normal operating pressures for an LT1? From what I know, the earlier years are supposed to run at a lower pressure of around 30psi due to difference in injector size.

 

Your pressure is fine as is stock is 41 to 45 psi.