There's a non-return valve in the filler and another in the inlet to the tank, the tank one might be stuck. Some multivalves have a manual valve on both the inlet and outlet, has it been shut off while the pipe was being replaced and not turn on again?
'96 Saab 900XS, now gone to a new home......
'93 Range Rover 4.2 LSE, Single point Lovato LovEco, also now gone.....
'98 Ex-Police Range Rover 4.0, Single point AEB Leo and R90E vaporiser.
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