To test the two fuel pressure dampers and the fuel pressure regulator for diaphragm leaks, there are a few options:

1. pull the vacuum line, see if fuel spits out. You can best do that with the fuel pump running. Do this preferably with a bridged relay, but you can do that with the engine running as well if the engine is cold. Just keep a towel near by as fuel on the engine is bad. If the engine heats up, STOP !! An engine fire is no joy.

2. connect a vacuum pump with gauge (Mityvac for example) to the damper/regulator to see if the diaphragm holds vacuum for at least a few minutes. Engine off please.

3. connect about 15 cm transparent hose between the regulator / damper and the vacuum tube. Make sure it fits tightly. Start the engine and just watch. You should never see any bubble or fluid.