Hi there,
I'd go with your conclusion: fuel accumulator. Easiest test (if you don't have a fuel pressure gauge) is to pull off the small rubber line in the back of the accumulator and block it off. Then start the car, wait 10 sec. and watch for leakage from the accumulator. If it does leak, the diaphragm inside is faulty. You found your problem.
All the best,
Dokta