Trying to revive a 2004 Rhino 660 for a friend. Have been sitting broken last 6 years. Some parts were missing and some wires were spliced. What we have done are replaced the stator, traced and corrected the known bad wiring, checked the timing, rebuilt carburetor (also bought a new after market one), new water pump and new ignition coil. Initially there was no fire, now it does. As we crank the engine, it wants to start, but as soon as we press the gas pedal, the engine stops turning or a loud back pressure thru the carb. and it stop turning. What causing this? I assume there will be less pressure when apply the gas pedal. Please help!