Kubota L3901 crank no start had a E-94 code had fuel all the way to fuel filter tractor will turn over but won’t start. Took into Kubota dealer wanted $4,500 for 3 new injectors tractor has 300 hours took it back home pulled injectors had them flow tested and the old man said they all passed. First they said one was stuck then upon pick up said 1&3 leaking out of return. I need help/ advice to