Does any one have any information on the woodward fuel system. Have a unit that will not start unless you remove the orifice mounted on the side of the carb. housing. If you remove the orifice fitting and install a non restricted fitting, unit will run but will backfire through air filter under a load. This has the tier III emission. It has 2 trim valves is there a way to test the trim valves. Regulator was replaced due to the oil build up. I have no information on these units, Thanks. Model#G25P-5 Serial #ML-00805.