Scag Tiger Cub w kawasaki 19.0 eng

[richard fay]

Had my Scag Tiger Cub for about 9 years. The middle of this summer it would start great cut at full throttle and then it would act like it either was running out of gas or flooding - start backfiring and almost stop. I would open up the speed arms and sit until it would come back to full throttle and then go on for a while and then it would repeat, this goes on for about an hour and then it just seems to clear up/stop happening. I thought I had it down to the right gas tank so I took it off and cleaned it. You would not believe the stuff that came out of it. Appareently when Scag drills the gas tanks for the mounting items they do NOT flush the tank so all sorts of twisted pieces of the tanks black plastic is left in the tank. So I thought I had it fixed. Nope. It is still doing it and now it seems to do so on either gas tank. have not flushed the other yet. I have replaced the gas line filter and the fuel pump thinking they were the problem. Nope still doing it. Have flushed the fuel system with carburetor cleaner, Nope still doing it. To me the weird part is it seems to stop doing it after it has been running for an hour or better. I sure would be grateful if anyone knows what the heck is causing this.
PS: the engine has always backfired when I turn it off. The dealer says that it just the Kawasaki 19 hp engine. Sure would appreciate it if anyone also knows how to stop this.

 

[Mad Mackie]

When this happens, pull in some choke which will richen the fuel mixture somewhat. If the engine RPM picks up with some choke, then you may need to have the carb removed, disassembled and cleaned. I also have run into several 17 and 19 HP Kawis that needed new ignition coils as they get intermittent at times.
But I would make sure that the fuel system is 100% beforehand, this includes the tanks, hoses, transfer valve, fuel filter, fuel pump and the hose connected to it that goes to the crankcase. This hose transfers the pressure pulses that occur in the crankcase as the engine runs and these pulses (varying pressure) operate the fuel pump diaphragm which in turn pumps the fuel into the carb. The fuel pump also has flow check valves in it which direct the flow of fuel in the correct direction toward the carb. The carb also has a fuel shut off solenoid installed in it which when the engine is shut off blocks fuel from entering the main jet. Crud can buildup on the tip of this solenoid and in the entrance to the main jet.
Another thought is engine overheating, crud can buildup in the engine cooling system that will slow down the transfer of heat to the circulating air. The engine can get hot enough to cause the incoming air/fuel mixture to vaporize when it should remain in an atomized state for complete combustion.
Just some thoughts from Mad Mackie in CT