THE PLT RPTD THE LT ENGINE LOST PWR ON 'VERY SHORT FINAL'. SHORTLY THEREAFTER, HE HEARD THE STALL WARNING. THE AIRPLANE ROLLED AND YAWED LEFT, AND CRASHED NOSE-DOWN SHORT OF THE RWY. THE ACFT WAS EXAMINED THE NEXT DAY BY AN FAA INSPECTOR; HE RPTD FINDING NO EVIDENCE OF A MECH MALFUNCTION. HE ESTIMATED THAT ONLY 3 GAL OF FUEL REMAINED IN THE LT MAIN TANK: THE RT MAIN & 2 AUX TANKS HAD SUSTAINED IMPACT DAMAGE AND WERE EMPTY. THE INST PANEL CONTAINED A PLACARD IAW AD 69-15-09 WHICH STATED THAT OPS W/ LESS THAN 5 GAL IN EA MAIN TANK WAS PROHIBITED. THE PLT INDICATED THAT HE THOUGHT THE UNUSABLE QTY WAS 1 GAL PER TANK. HE RPTD THAT THE FUEL GAUGES HAD INDICATED 7 GAL IN EA MAIN TANK AND 10-11 GAL IN EA AUX TANK DURING FINAL APPCH, AND THAT HE FOUND AN ESTIMATED 5-7 GAL OF FUEL REMAINING IN THE LT MAIN TANK SHORTLY AFTER THE ACCIDENT. HE NOTED THAT HE HAD STOPPED USING THE AUX TANKS EARLIER IN THE FLT WHEN THE RT ENGINE BEGAN TO RUN ROUGH; THE ROUGHNESS CEASED WHEN HE SWITCHED BACK TO THE MAINS.