when we tried to start it sometimes it will not energize the fuel pump. You don't hear it come on. When it does come one it will start. But when it doesn't it will not start and gives a check engine light. The codes are all low voltage to fuel pump ect..... We changed the battery and check the battery cables to see if that would fix it. It did not. Where should we look? We really need this fixed.

[2015 Z Force 800 53/Trail EPS]

Check the AUX relays. Also check the fuel pump relay.

when we tried to start it sometimes it will not energize the fuel pump. You don't hear it come on. When it does come one it will start. But when it doesn't it will not start and gives a check engine light. The codes are all low voltage to fuel pump ect..... We changed the battery and check the battery cables to see if that would fix it. It did not. Where should we look? We really need this fixed.

Check gas pedal electric plug.  Mine recently did same thing.  I unplugged electrical plug to gas pedal and it was damp and had been for a while.  The PINS were corroded.  I cleaned up the PINS and used dielectric grease plugged it back in, fixed problem.