Originally Posted by GVK.

Injection Pump Belt
Removal

Remove timing belt as described previously.
Ensure timing pin or 6 mm drill bit (CAV) located correctly in injection pump sprocket Fig.10399.6.
Slacken tensioner bolt Fig.10399.12. Lift tensioner against spring pressure. Tighten bolt.
Remove injection pump belt.
Slacken injection pump sprocket bolts Fig.10399.13.

Installation

Ensure crankshaft web against timing pin Fig.10399.4.
Ensure timing pin or 6 mm drill bit (CAV) located correctly in injection pump sprocket Fig.10399.6.
Fit injection pump belt. Slack side of belt must be towards tensioner. Observe direction of rotation marks.
Slacken tensioner bolt Fig.10399.12. Allow tensioner to operate. Tighten bolt to 45 Nm.
Tighten injection pump sprocket bolts Fig.10399.13. Ensure bolts not at end of slotted holes in sprocket.
Fit timing belt as described previously.

(I never used to slacken the pulley bolts, it makes the belt a bit harder to put on but you don't get any issues with the timing being out. )