if you really want to save this tank i would go get that stuff called pc plastic. i've never used it on a gas tank but it works pretty good. every time i have seen people try to use those plastic welders it never worked out right. Just go to any hardware store and they should have it.
91 yj, 4.0, AX15, SOA, 8.8 rear, 4.88 gears, 2.5 inch springs front, m.o.r.e shackle reversal, m.o.r.e shock hoops, 3 inch springs in rear, bilstein 5150's, shock bar, m.o.r.e traction bar, lockers, m.o.r.e high steer, SYE, old school bronco cv shaft, tube fenders, 36 inch tsl's