[urq] Warning about Fuel Pressure Accum.

[a4kcstq at comcast.net]

The fuel pressure accumulator helps to maintain residual pressure by storing a small quantity of fuel under pressure.  It also damps pressure oscillations, as Ben correctly pointed out.
There is a specific residual pressure test (in Bentley) for CIS systems.  It's something like 35+ psi after 10min is OK.  Remember that there are 4-5 openings in a CIS system (excluding bad connections) and you need to check all 5 if your residual pressure is not OK.  Loss of residual pressure will potentially cause hard starting and/or vapor lock.
1.  Fuel Supply line (the fuel pump check valve)
2.  Fuel Return line (fuel pressure regulator in the fuel distributor or external)
3.  CIS injectors
4.  Cold start injector
5.  Frequency valve (if equipped)
You can lose pressure even if the accumulator is good, it just means you have a leak that's bigger than the storage capacity of the accumulator.
Some CIS systems (4kq in particular) have a fuel pump prime feature that bumps the system up to ~80psi just prior to starting.  This won't help prevent vapor lock, however.
-Peter Lines