Abstract: Windshield repair tool has an injector for injecting liquid resin into fractures and pits in broken windshields. The injector has an injector cylinder and a plunger that applies pressure to resin in the cylinder for injecting the resin into the fracture or pit. The plunger itself includes an outer sleeve and an inner plunger component biased forwardly in the outer sleeve by a coil spring. The pressure on the resin is monitored and can be controlled according to the amount that the plunger stem projects from the outer end of the plunger sleeve. This avoids insufficient or excessive filling of the fracture or pit.