blacktrain

Replaced the injector, now when I turn the ignition on you can hear the fuel pump like normal but when the engine turns over it seizes up, pull the spark plug out and the cylinder is full of fuel, a lot of fuel, turn the engine over with the plug out and huge amounts of fuel blows out of the plug hole. What have I done wrong? I appreciate your help, thank you!

Finally found the problem. The exhaust pipe that has the O2 sensor was the problem. The exhaust pipe is a pipe within a pipe, I noticed a lot of exhaust fumes were coming out around where the O2 sensor threads in so i knew there was a exhaust leak. I removed the pipe and plugged one end and plugged off the O2 sensor hole and applied air pressure to the other end, i sprayed the pipe with soapy water and noticed it was leaking around the O2 sensor hole . I then took a die grinder and cut the outer pipe apart removed the piece i had just cut and the inner pipe was all rotted out near the end that bolts to the head. So the O2 sensor certainly could not do it's job. I replace the exhaust pipe and life is good once again. I greatly appreciate every one's help.....

Have not resolved the problem yet. There is no sure way to test the ECU and I hate to purchase one if that's not the problem. I have pretty much covered everything else. Fuel pump tests ok, no water in the fuel, new plug, new map sensor, new throttle body idle control sensor, new air filter, no vacuum leaks, not sure where to go from here. The machine was running perfect, and we parked it for about three weeks and when we went to use it again, that is when this all started. It starts right up, idle's perfect, if you go easy with the gas pedal it will run ok up to about half speed. If you step right down on the pedal it will die out. If you baby it up to half speed and step right down on the pedal, it will die then also. I appreciate everyone's help.

The fuel pump was removed, cleaned and pump pressure checked. Fuel was removed from tank, tank was wiped out with rag since fuel pump was out. Fuel line is new and there is a fuel filter inline which is new also. Thank you for your thoughts, I appreciate it...

2014 Massimo MSU 400 idles perfect, runs ok up to half speed. From half speed if you step down on the gas pedal all the way engine dies. Engine is fuel injected, the map sensor, and the throttle body idle control sensor, and the fuel injector have been replaced. Also the fuel pump was removed and fuel pressure is ok, and fuel was checked for water. Air box and air filter have been cleaned, also replaced spark plug. From a dead stop if you step right down on the gas pedal all the way it dies, if you baby it, and go easy it will run ok until about half throttle, then after that it will die as you start to push down more on the throttle for top speed. Any ideas? I appreciate anyone's help...