MikeD.

iTrader: (1)

So I had a question about fuel pressure. 2006 Sierra that I upgraded to a Walbro 255 (gss340). Started having some starting issues, cold start would be funny, and hot starts would have to cycle the key twice to start decent. So I put a fuel pressure gauge on it today, and as I expected, it will not even hold pressure during the prime. Jumps to 58/60psi, and bleeds off almost instantly. So I know there's an issue there. With the engine running, it holds a steady 58/60psi, but at WOT is drops a couple psi to about 54ish. Is the wot fuel pressure normal? I assumed at wot is would increase in pressure not decrease. Or maybe I'm wrong. Anyway, I know I need to pull the pump and see why it's bleeding off, but just wondering if the wot pressure is right? Thanks guys

Vortec350ss

iTrader: (20)

The returnless systems tend to decrease pressure at heavy throttle... its far from ideal.

As far as the start up issues it seems to point to a regulator problem I would think but I cant say for sure.