The pump has an internal valve that will try to keep the pressure. The aftermarket pumps don't seem to work as good as the original GM pumps in my opinion. Miner bleeds off too on my Walbro. The main thing is that your fuel pressure doeant climb past what you want .

Did you ever make any progress on this? Can you post your tune and a log, I might have some time to look at it tonight.

 

not really. Its still going to 11.5-12.5 when I let of the gas. Figured its better than running 18+ on decel lol

 

Mine does too, but then again I was never able to get reliable data for my injectors. Mine hovers right around 11.5-12 on decel. Everything else is real close though...

 

For some reason I can't open that tune. I tried on 2 different computers.

 

Same issue here, try posting your tune file again.

 

That's the key "reliable data". Depending on the operating system being used and what tuning software you might be using but their is a table that has the final say on minimum pulse width that can mess with you.