fuel pump issues 93 2.3l

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helping an elderly neighbor and need help 93lx 2.3l asked me to change fuel filter car wouldnt start. realized right away wasnt the problem didnt hear pump when ign was turned. dropped tank tested voltage at tank 7v?? found relay saw o2 sensor wire had melted to manifold (someone helping him last weekend left it unplugged) said it ran after placed new on order. talked to a few people most said it probably fried relay, new $240 relay separated and taped wires for o2 before installing, no change?? thinking it shouldnt be fusible link (would have 0volts at pump right?) im thinking bad wire please help