I basically installed most of the fuel supply plumbing from my donor, and there was no check valve in it. When you go key on, the pump will run and pressurize the system, before it goes to start. The fuel pump I have won't let fuel back flow, so maybe it's incorporated there. When I tested the line for leaks by jumping the wires, it pressurized right up. Later I had to take the injector fuel rail off to replace the cross hoses, there was still pressure in the fuel rail after about 2 hours.
No idea on aftermarket, but most OEM systems have a check valve in pump. Main function is as stated, retain pressure after shut down, gives faster start. If it's a separate unit, I'd install it somewhere readily accessible.
aftermarket... I was wondering with a return system if it would hold pressure with the check valve installed in the feed line at the pump. or does it need to be in the feed line between the regulator and fuel rail?
I used an aftermarket pump, and have an open return line. My fuel rail and system is a stock ford EFI system, so the Atomic might be different, I would expect they would provide guidance on what to do.
Total shot in the dark but I would think a vacuum style regulator would kill all fuel return when there is no vacuum present. Reason for my thinking is WOT you need all the pressure for the added demand and shutting down return flow would give you that. I could be completely wrong.
Partially... Without vacuum, factory fuel pressure reg max out at 39 psi. In operation with vac on regulator, pressure is closer to 30-32 psi. These are in the return line to tank, dead ended return line, blocked regulator etc will shoot pressure over 100 psi. Assuming no leak on pressure side, this maintains fuel in rail. It's the closed check valve that maintains pressure on pump(supply) line. I've witnessed a fresh pump in a Turbo Coupe with stuck regulator making 125 psi. Returnless systems regulate pressure by varying pulse width(basically voltage) to pump motor. These system uses a electronic pressure sensor on fuel rail. Using info from sensor, throttle angle, air flow through MAF etc, PCM determines pulse width.
my system goes from tank to regulator and return to tank. then from regulator to fuel rail. my regulator is a vacuum style regulator set at 58 PSI (W/no vac) fuel pump is non P/W (on/off).
