Ferocity02

iTrader: (59)

With the key on engine off, the fuel pump primes and gives me around 50 psi, but it quickly falls back to zero as long as the engine/fuel pump aren't running. It will fall about 2 psi every second right in the beginning but slows down as the pressure falls. After about a minute or so it will be back to zero.

A few months ago when I last checked, it would hold fuel pressure for hours, if not all day. I can't find it now, but the Chilton manual said something along the lines that the fuel pressure should not fall more than 5 psi for every 5 min. There does not appear to be any other issues. It drives just fine, plenty of fuel pressure in boost.

Could this be a fuel pressure regulator issue? Perhaps the stock FPR doesn't like the boost?

Here is a video I found, it's not mine, but it's almost exactly what mine is doing: OBS Silverado fuel pressure test - YouTube

Chevy_King1500

iTrader: (7)

mine will prime to 50psi then fall to 40 and hold there

walbro 450 pump

Bit

iTrader: (1)

There is a check valve inside the fuel pump assembly that goes bad and let's fuel drain back. Have seen the regulator go bad too.

Ferocity02

iTrader: (59)

I'll pull apart the regulator and see if anything is awry.

The fuel pump is a Walbro 255 and is fairly new, 15k miles I'd guess. But I was planning on putting in a new pump anyways, the little 255 is maxed out.

01ssreda4

iTrader: (87)

Bumping this for any conclusion....

SlowDude

iTrader: (4)

Thats a long long bump bro.....lol

03sierraslt

iTrader: (22)

Depends if it's a factory or aftermarket regulator.

01ssreda4

iTrader: (87)

Found my issue, it was the regulator in the pump assembly.