Fuel Accumulator vs Fuel Check Valve
 

What is the best way to test for a defective:
a) fuel accumulator (next to the fuel filter)
b) fuel check valve (adjacent to the fuel pump)

Any ideas what the symptoms might be and how they would differ between the two?

96462095100 - fuel pump check valve
91111019702 - fuel accumulator

I suspect the symptoms would be the same or similar. Hard starts, if it hard starts hot it could be a leaking injector or two.

check for leaks in the accumulator.

if there is no leaks and no fuel at the accumlator then it could be a check valve (one way valve) allowing fuel to syphon back into the tank. If you get the valve out you should be able to blow through it one way but not the other.