It seems to me that it should be obvious that an aftermarket fuel pressure regulator advertised as "EFI" should hold pressure at key-off just like a stock EFI system, but apparently the people who make go-fast parts didn't get that memo and a lot (most? all??) of the regs on the market don't do that. Worse, very few of the makers care enough to give specs on their products that would allow a buyer to easily tell ones that do hold pressure from ones that don't, and it's a complete crapshoot as to what you'll get for your money.
Aeromotive is good stuff, right? They know what they're doing? Their FAQ says:
JFC. OEM regulators are not holding key-off pressure strictly for emissions reasons; they are doing it because FUEL AT ZERO PSI IN A HOT FUEL RAIL BOILS OFF TO NOTHING every time you have a hot-soak. This is Not Good. Not good for the injectors, especially. This is why the OEMs do it, because that's how EFI should work, not because of emissions. If you do it WRONG it increases emissions, that's not the primary reason for doing it *right*.6.) I?ve installed my new Aeromotive bypass regulator. Fuel pressure seems to adjust fine and holds great when the engine is running, but when I shut the engine off, pressure drops quickly to zero. Shouldn?t the pressure hold like it did with a stock regulator?
No, Aeromotive EFI bypass regulators may not seal perfectly when the pump is off. They are engineered for the highest possible performance when the engine is running. OEM regulators must hold pressure for 30-minutes after shut-down to pass EPA emissions standards. At Aeromotive we know our customers priority is to have the best possible flow and pressure control when the engine is running and we don?t compromise this standard to force the regulator to seal when the engine is off. If extended crank or hard-start becomes a concern, first allow the pump to run and prime as long as possible after turning the key to the run position, then start cranking the engine, just before the pump shuts off. If the priming cycle is too short to allow the engine to start easily with this approach, extend the priming cycle in the ECU if programmable, or ad a timer board or momentary button to the fuel pump run circuit.
Can anyone with first-hand experience recommend a regulator that's verified to work like it should so I don't have to waste several hours trying to get info from manufacturers, assuming they'd even know? Universal style, -6 in/out is fine, should be able to deal with the bypass needs of a typical 450LPH intank pump. Nothing special. Just needs to be a proper EFI regulator and not a carb regulator with a big fat spring in it.
/rant over