My holley blue pump died on me the other day, i bought a new one, removed my stock lift pump and just run the holley with 1/2" lines. when i first ran it i got a steady 12psi out of it, i streached the spring, and now the pressure bounces really fast from 12-25 pounds! it bounces so hard i can hear my guage tick. if i look under the truck, the fuel lines twitch from the pressure surges. it does it no matter the throttle position.

 

ditto: same problem, going to get the morroso spring kit wed.

Did read on gasser forum that running " dead Head " ( there words )
will shorten the life of a LP,
They reccomend a return style Pressure regulator ( 3 port )

 

you overstretched the spring. get a replacement and install it as you get it. you will have plenty of press before you ruin the spring thinkin ya need more...cuz ya dont. itll be perfect as is.
my pump has been runninf flawlessly for 2 yrs and over 60000mi and other than the crappy relay i wired in its an excellent setup for 110$. runs 15-16 and around 11-12 wfo...always

 

Before i streached the spring i could pull it down to 5psi wot. i didnt' streach it much at all, where do you get the replacement spring?

 

Mine spring kit is a stock item at the local speed shop ( out of stock )
should be there tommorrow morning,,

Also may try summit or jeggs catalog..