This Komatsu FG18HT-17, serial number 670347A with a 3.0 Mazda engine in it will crank all day long with multiple spits and sputters like it is going to start, only to go back to cranking. Had a bad cam and crank sensor when I first looked at it along with the codes to confirm that. I have since replaced the crank sensor two more times, the last time with a special metallic sensor that was supposed to fix this issue. I have also replaced the main injector and the fuel pressure sensor. When it is cranking, it will not start with any type of starting aid so I think fuel is not the issue. I am getting good spark and the engine will start at times, and it runs really good when it does start. Any help would be greatly appreciated. Thanks.