I agree with all of you, and I'm familiar with fuel pump check valves and their purpose. I was just wondering if there were certain regulators that "bleed down" more slowly than others. What I've learned is that there ARE regulators that bleed down more slowly... according to Racetronix those are the Mallory's and the Accufab's. I ordered a Mallory and installed it over the weekend, and the gauge goes right up 58psi key-on and bleeds down more slowly than my old Phenix regulator (which bled down to 0 damn near instantly). With the Mallory, within 4-5 seconds the pressure is down to 20psi, then after 30 seconds is down to zero. This is obviously a failure of the Walbro 450 check valve, and the pump did the exact same thing when it was brand new and pumping through stock fuel lines. I've had hit and miss luck with fuel pumps of all brands when it comes to check valves holding a prime... Walbro, Aeromotive, AEM, etc all seem to be similar. Funnily enough, my 2000 Tahoe with 195k miles and the original fuel pump starts right up every day on the first crank. My solution will be to install a proper -8AN inline check valve right after the filter (I have my filter installed a few inches from the bulkhead fitting on top of the assembly). Like this one from Russell. I will also check into the "prime time" that Atomic mentioned in hpt...

 

I do show several different tabs for fuel pump prime time in my 2005 OS... In my brother's E67 OS I don't see those tables at all. Here is mine. Another interesting field to change is actually "Prime re-enable time." By lowering that value to say, .5 seconds you should be able to click the key rapidly a couple times to prime the pump over and over?

 

I put a -8 flapper style check valve right at the fuel pump bucket. zoom in and look right after the 90* fitting coming out of the bucket. I believe you want the check valve as close to the pump as possible.

 

I like the look of that! I will do the same