It will be a very typical regulator - and no spring WILL make no pressure. I've rebuilt and modified those regulators to make them adjustable - friend's 350 TBI engine was running lean due to a combination of lower than spec pressure and a modified Throttle Body. The regulators are, as I said before, notorious for being in-accurate. General spec is between 9 and 13 psi. This one was running at about 8 and dribbled. We set it to 15 and got a real good atomized spray pattern, the fuel consumption dropped, power improved, and the truck didn't run hot any more.
If he followed my instructions in my last post he'll KNOW where the problem is NOT, even if it doesn't pin down exactly what the problem is.
I've worked on this stuff a lot over the years - back when that thing was current, but not so much today.