that is the model number,,,I was asking for the serial number, but thanks, and now you have answered the question that having the serial number would have answered, (which system and version your truck has)
22710 fu460 is what Mitsubishi forklifts and Cat Lifttrucks calls 'the injector driver', it sends the pulsed signal to the primary/main injector. it's functions are inside the ECM on newer that 2007 machines. I still think it is the relays, as long as the key switch and it's wires are good