You are not going to be able to interupt the fuel flow return line. First, it is not an easy thing to do as most FI systems run close to 120 psi before the pressure regulator. Second, the fuel pump will shut down after 1-3 seconds if the electronic engine control does not see a signal from the distributor.
The return line is quite easy to get to and is after the pressure regulator, In other words, the pressure regulator on this vehicle works by effectively restructing the return. For maximum fuel pressure, it would completely restrict the return. In this case, since the vehicle isn't running, the retun will get all the fuel. Also, the fuel pressure at this point isn't going to matter because it is going right into a 55 gal drum.
As for the running the pump thing, in this engine it is an airflow meter that does what you are talking about. If there is no airflow, it shuts the pump off. But there is a diagnostic connector where you can place one jumper ( a paper clip will do) to directly energize the fuel pump relay and run the pump manually.
It is a very simple operation. Remove the return hose from the regulator, put the hose to the drum in its place and jumper the connector. Watch the fuel gauge until it reads about 1/4 tank and then pull the jumper and replace the hose. Takes seconds to set up/tear down.
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