What does this code mean?

[DTH357]

My truck keeps tripping this code,and I don't know what it means so I don't know where to start looking.The code is 251 and says injector pump fuel metering Ctrl A Error.

[Biringen]

you can try Changing the PMD, and reset codes
Take off battery lines, for a while, them put them back after 15minutes
If you dont have a GM tech2 reader or equal

if same code keeps popping up
Change the Injection pump..