DIY External fuel pump setup on C5 Corvette regulator setup?
 

I know there's a lot more knowledgeable people on this board than I so I figured it best to see what the experts recommend.

I have a 408 LSA supercharger setup in a C5 Corvette that was running out of fuel system on the dyno. It was important to me to leave the intank pump and bucket assembly stock for various reasons over putting special hangers and dual intank pumps.

Anyways I now have the stock system functional being fed to one leg of a Y block before the aftermarket fuel rails. That setup is in a loop with the regulator at the end and I'm using the factory return line. (this is an early C5 with a factory return. The regulator is a holley clone 8an deal.

I now have an AEM 400 external that is tapping off the drivers tank module that will run via Hobbs switch. This is plumbed into the other leg of the Y block at the fuel rails.

Doing it this way I now have a shared regulator for both systems and a common return.

I have not driven the car yet but this is what I've noticed so far. Key on engine running the intank pump runs at 51 psi adjusted to 58 with the boost reference hose off.

Engine off intank pump off but jumper the AEM 400 to on and the fuel pressure is around 55 with no changes to the regulator.

If I start the car and then jumper the AEM pump on the fuel pressure goes to like 70 at idle. Stays running fine and I have not driven it yet so I have no idea what it would really do under boost with the boost reference hose hooked up.

Am I missing something here? Is my simple logic flawed in a sense that I am going to need a separate regulator to control the intank pump so the pressure doesn't go unnecessarily high with the external pump on?

Open to any and all thoughts and I certainly don't mind making any recommended changes.


Se attached pictures of what is installed.

https://cimg0.ibsrv.net/gimg/ls1tech...96881468c6.jpg
https://cimg1.ibsrv.net/gimg/ls1tech...a32b1d754d.jpg
https://cimg2.ibsrv.net/gimg/ls1tech...1c1a698919.jpg