Sealing
Dribble standards have become tighter in recent years. The pintle injector illustrated in Fig. 5-26 should remain fuel tight under 80% of NOP for at least 10 seconds. Note and correct any other source of leakage.

Chatter
Injector opening is normally accompanied by a sharp “pop,” which suggests that the needle retracts cleanly. Verify this action as the pump lever is cycled rapidly. However, leaking injectors can be made to chatter and some perfectly good throttling pintle injectors pop open, but refuse to chatter, no matter how adroitly the pump handle is worked.