Hello everyone, I have a problem that's making me scratch my head. Yale model glp060tgnuae serial a875b11192 with a Mazda 2.2l and aisin propane system. It came in to the shop for a blown head gasket (steam coming out of exhaust). I replaced head gasket and installed New head. Set mechanical timing, adjusted valve lash, New manifold gaskets, New cap, rotor, plugs and wires. Now the problem is it doesn't want to start. If you keep cranking, it back fires from carburetor. Rechecked mechanical timing and made sure rotor in the right place. Over hauled aisin regulator since I noticed Lp keeps coming out and engine started when feed hose pulled away from carburetor but still same thing. Did compression test and it's 155 psi all the way across all cylinders. Had spark testers on all the plugs and they all fire good spark. I am not too sure what else I'm missing. Any pointers would be appreciated. Thanks in advance.