Didn't see you said it had spark, Many times when a mod sled dies on a hard pull its because it siezed, So I would look at the pistons and check compression to make sure. Like the other guys said put a bottle cap of fuel in a cylinder and see if it will fire. If it does then Check your fuel pressure, If you have 42psi or more its good, sometimes the pump will plug or go weak and if you hook up the polarity of the fuel pump wires backward it will run the fuel pump in reverse and clean it out, then hook it back up, and see if it pressures up right. then check for power and ground to the injector, if that is good then pull the injector and pull it over to see if it is spraying. It could also be that there is water in the system instead of fuel so it would hurt to drain the gas put new in, pull the fuel line off and hook up power to the fuel pump and run some through.
