09 kingQuad 450 axi 4x4 skipping , back firing in throttle body fuel pressure is 43 psi, injector putting out fuel, new spark plug, will crank but won't take fuel, no codes I need advice

 

Clean the injector out. 9 times out of 10 the filter in the injector has picked up debris from fuel and partly blocked. I give the injector a blow out with the air line and off the bike goes. If it isn't that, the trouble with EFI systems is if a sensor is telling lies, unless it goes beyond "normal" range, the self diagnosis system won't pick it up. For example if coolant temp sensor says engine is cold when it is hot, the computer will overfuel, but there will be no fault code as the temp signal is still in normal range. Throttle position sensors can do the same thing.

Might be an idea to post in the Suzuki section next time 450KQs are not usually "Kids Quads".