My 95 has two plastic arms on the very top and bottom of the release assembly that press against the fuel door when closed, popping it open when it's released.

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I suspect that your Gen II.5 is probably the same design and the arms are broken off.

95 Montero SR
3.8 MIVEC, Advance headers, 2 1/2" exhaust, Magnaflow muffler, OME shocks & rear springs, 2" body lift, 3" tank lift, 4.90s, TRE front locker, factory rear locker, Roger Brown Rock Sliderz, 315/75r16 (35") tires, Sport big brakes