[Gator67]

I'm running a Terminator X with a deadhead return style setup (Aeromotive fuel pressure regulator before the fuel rails) with a Vaporworx PWM controller & Walbro 340lph in tank pump. Fuel pressure is rock steady when the engine's running, however, the fuel pressure drops to zero in couple seconds when I turn the key off. The only negative is that the starter has to spin an extra second or two. Not a big deal, I can extend the priming cycle, but it doesn't seem normal to me. I verified there are no leaks, including the injectors. Aeormotive says this is a common issue with their fuel pressure regulators, so I'm wondering if there are other options that hold the pressure longer.

[JLMounce]

A PWM controlled dead head pump creates pressure by creating flow. If there is no flow, any pressure in the system will leak back through the pump veins. In fact this is typical of pretty much anything with an electric pump, regardless of setup.

It's why modern cars prime the fuel pump during innocuous entry events so that it's ready to go once the user commands an engine start. The manufacturer anticipates an engine start and primes the system early. Both my 2014 Grand Cherokee and 2019 Tundra do it as soon as the vehicle unlocks from the remote, or if unlocked, when the driver door opens. The Tundra even cycles it's entire fuel system for about 10 minutes every so often while the truck isn't in use. Pretty weird to go out to the garage for something unrelated and you can hear the pumps running.

[Gator67]

Thank you for the reply, makes perfect sense.