As already mentioned, you do not need, nor do you want, any change in pressure inside the fuel tank. It should be at atmospheric pressure, pump on or pump off.

Are you *sure* there is no fuel being pumped to the engine? Pumping fuel to the engine is one thing. Getting fuel from the injectors is a whole 'nother deal, as it involves many more components; that would include, for instance, a D-jet wiring harness that is most likely approaching 40 years old and has recently been "disturbed", to say the least.

By the way - you mentioned that you are awaiting ignition parts, so I must point out that if you don't have a working FI type distributor (or at least working FI trigger points), you will *not* have fuel from the injectors. Regardless of how much pressure is built up in the fuel supply portion of the system, if the injectors aren't commanded open by the computer, there ain't gonna be no fuel delivery... and you have to have the FI trigger points in place (and working) to tell the computer *when* to open the injectors.

Normal working pressure of the D-Jet system should be 28 psi, measured at the fuel rail (or someplace between the pump and the FPR.
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Gary L - 1971 142E ITB racer, 73 1800ES, 02 S60 T5
BlueBrick Racing