Accufab FPR - when does your PSI drop off?

Dan SS2471

Active Member
Read a few different posts and if possible, would like to get a definitive answer to two questions / scenarios while observing the hood mounted FP gauge.

1) At key on, no cranking and after the pump increases to base PSI, does your gauge drop to zero PSI after a couple of seconds?
2) At key off after driving, does your gauge drop the same as scenario #1?

I've read some yes some no....The NOs have been, it drops to zero after a few minutes.

Suggest you replace with a Kirban’s Aluminum FPR or Racetronix FPR.
Never had any such issues with either of these


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Ran an Accufab every weekend spring to issues.
I understand that there has been a design change on the newer Accufab FPR’s which are now offered & they are prone to issues not experienced on the older (original) design .
Maybe someone better versed on this can chime in & share their knowledge
My accufab behaves like my other regulators. Pressure drops when the pump stops but doesn’t drop to zero. Drops to the 20’s and 30’s.
I have tested two Accufab regulators (one old and one new) and one Kirbans regulator on the same car on the same day.

I did the test on my 86 GN, it had an Accufab on it when I purchased it, although I don't know the exact age of this regulator I do know it's at least a 2011 or older. I purchased a new Accufab when I upgraded the entire fuel system (injectors, pump/sender, tank, fuel lines, wiring). What I found is that the new Accufab regulator will drop to 0 rail pressure the moment the fuel pump is turned off. The old unit will hold pressure and slowly drop from 40ish PSI to 0 over about 30 minutes. Before installing both units for this test I did disassemble them to make sure they were clean and no issues internally.

Now on the 87 WE4 I picked up a Kirbans regulator and noticed it held rail pressure for hours after the pump shut off and slowly went to 0. For a test I swapped the Kirbans with the Accufab on the 86 to see if my pump or injectors were to blame for the drop in rail pressure after the pump is off. On the 86 with the Kirbans regulator it held pressure the same as the 87 WE4, took about 2 hrs for the rail pressure to drop to 0. So there is a difference between the Accufab and the Kirbans in regards to the fuel rail maintaining pressure after the pump stops.

I am logging fuel pressure in the 86 and did not see a difference in fuel pressure at WOT between all 3 regulators, so I wouldn't say the Accufabs are causing issues, but can say they do not seem to hold the rail pressure as well. Does this really matter? I'm not sure, but I don't think it does. The Maybe someone with more experience can chime in.
I ask the same question. Does it matter?

Seems like engine start may be the only condition where it might possibly be a factor.
My older Accufab pre 2011 hold good too, not as good as Mblum. I personal see a upside to dropping to 0. If its working good and maintaining good fuel pressure and drops to 0 at key off no worries of fuel liking past injectors and having raw fuel laying in intake to black smoke at startup or washing down cylinder walls and contaminating oil.
We don't want to have a leaking injector either but a controlled leak to tank is the best alternative
So, how are the tests conducted in order to eliminate system components other than the regulator?
A "new" system... Psi drops. Is it the injs, the pump, the regulator, the in-tank plumbing?
Same questions when doing a T/S on an existing system.
Inquiring minds want to know.
I had the fuel pressure drop to zero as soon as I keyed off. It was the check valve in the fuel pump. It didn't affect pressure at WOT. Having said that...when it occured, I swapped in a new pump.
Good stuff here. Since May of 2022 up until current day, I've replaced pretty much the entire fuel system with the exception of the tank and INJ harness. Was it all necessary? Probably not. But now I have a lot of room for growth. Not that I plan on turning things up any time soon. But's all there.

The reason I asked this question is because I replaced the 10+ year old Accufab with a new one not long ago. I've been monitoring the gauge (mounted at the windshield), which I had never really done before unless I was checking line-off or adjusting it. So I can't say with certainty that the old regulator EVER held pressure when keyed off. But I did notice it while doing all of that 'visual logging'. The new unit behaves the same way. As of a couple of days ago as I mentioned in another thread, I'm logging FP and it's now without question rising 1:1 up to 24lbs of boost and it's holding pressure just fine. I thought about going with Kirban's FPR but I think when I went to order it, they were out of stock. I think.

So there are varying opinions and I'm not a fan boy of any particular product, but it's ensuring to see that others whose fuel systems are running ok are seeing the same results as me.

Thanks for all the feedback.
And by 'Ive replaced'...I mean with a LOT of guidance from Murphster and Pacecarta and install help from Paul. No way I could have figured out what to install and why and for a lot the upgrades, the means to install them. Scott is a few hundred miles away now so it's a good thing we both have unlimited text plans!
So, how are the tests conducted in order to eliminate system components other than the regulator?
A "new" system... Psi drops. Is it the injs, the pump, the regulator, the in-tank plumbing?
Same questions when doing a T/S on an existing system.
Inquiring minds want to know.
Agreed, eliminating possible issues with plumbing, pump, injectors ect is important when pointing the finger at the regulator. In my case I did do my testing mentioned above all in the same weekend with no other changes other than the regulators. What prompted my test was I wanted to see what was causing my fuel pressure to drop to zero at key off, but I wasn't chasing an issue, more curious than anything.