Adjustable fuel pressure regulators: Which ones hold static rail pressure?

[supraguy@aol]

I was wondering if anyone of you could share their experience with aftermarket fuel pressure regulators.
The one I currently have is just Ebay crap, and I'd like to upgrade. I want one which holds some static(resting) pressure in the line, rather than draining down to zero after shutoff.
Do any of the aftermarket brands do this? I am considering Aeromotive, Fuel Lab, SX, etc.
Post up what you've had, and what your experience is with it.

 

[Aleo24]

I am using a Proflow Efi fuel pressure regulator. It holds line pressure but slowly drains over time, not sure if its bleeding the pressure out or the pressure is flowing back through my Walbro.

 

[7M4EVR]

I have an aeromotive and it drains back down slowly after shut off.

 

[IJ.]

Only time it makes a difference is for hot starts due to the way the fuel pump circuit is set up, it needs to see engine rotation before you get pressure, you could install a prime circuit something simple like a cap and a diode to give xx seconds at key on would do it, or a timer.

 

[supraguy@aol]

What I normally do to start, is click over to engage the starter for about a 1/10 of a sec, and that engages the pump for 2 seconds, then I start normally.

 

[hvyman]

Why not just crank? Won't ever get pressure to hold over night. Plus the 1-2 revolutions in cranking before starting gives the engine some oil prime.

 

[Suprapowaz!(2)]

I have an aeromotive and it drains back down slowly after shut off.

Same here.

 

[hvyman]

Generally all fpr will hold a pressure for a minute and then drop or slowly drop down right after. Usually after a a few minutes there is a minimum amount to no pressure.

 

[IndigoMKII]

Why not just crank? Won't ever get pressure to hold over night. Plus the 1-2 revolutions in cranking before starting gives the engine some oil prime.

I wouldn't say that. Mine holds pressure over night. Mine held pressure for over a month.

Dont ask how though, its the afpr kit from driftmotion with a walbro 400.

 

[Suprapowaz!(2)]

Wow, maybe the walbro 400 doesn't leak back. That's interesting.

 

[Poodles]

Yep, I doubt it's really the FPR leaking the pressure, it's more likely the fuel pump (or injectors)

One could always install a check valve, but it's really not needed as the system primes quickly. Maybe if you're running a tiny battery...

 

[jetjock]

Most pumps are checked. Anyway, as poodles pointed out the rest of the system should be verified at some point. And as IJ said, rest pressure is there for vapor suppression/hot starting and priming either automatically or with a switch would solve it...

 

[supraguy@aol]

This is all good to know.
I emailed Aeromotive, and they confirmed that the 340 Stealth pump does have a check valve.
I suspect I might have a leaky injector or two. I guess I'll have to pull them at some point, and have them cleaned and tested.
Regardless, I ordered a Fuel lab afpr with a marshall liquid filled gauge, to replace my Ebay $18 unit.


...don't judge me. I was young and foolish when I bought it back in the day.

 

[7M4EVR]

What if the AFPR is mounted and sitting higher than the rail and feed line; would that have anything to do with it? Guess, what I'm saying is maybe there is still pressue built up in the rail, but not enough to defy gravity and come up the feed line to the gauge and register? I'm probably way off, just curious...

 

[jetjock]

Yeah, a bit off there padawan. Better to forget you even brought that up

 

[IJ.]

yeah, a bit off there padawan. Better to forget you even brought that up

lmao

 

[MarkIII4Me]

I stuck a smoke tester in the vacuum port of both my Aeromotive AFPR and my friend's Aeromotive AFPR (different models). Both showed smoke coming from the top adjustment bolts. I turned the bolt to raise pressure, put a small o-ring at the base of the bolt, then tightened it to correct pressure. As it tightened it pinched the oring between the bolt and housing. Then I put on the securing nut. Tried the smoke test again and no leak detected. The pressure gauge now shows that the AFPR is holding static pressure.

Not sure if this is just some fluke, but it work on two separate Aeromotive AFPR's. I called Aeromotive once and asked about the leak I found around the adjustment screw and they said that this was normal and does not affect operating pressures.

 

[7M4EVR]

Yeah, a bit off there padawan. Better to forget you even brought that up

LOL...Point taken. If the pump is checked, and my injectors are brand new RC's so I'm pretty sure they are not leaking fuel, can you give me some other possibilies of why there wouldnt be static pressure in the rail? Other than the AFPR not working properly...

 

[IndigoMKII]

Pinched an o-ring while installing the injectors in the rail.

 

[supraguy@aol]

That would cause a visible external leak, though.