There are four standard tests—spray pattern, NOP, sealing effectiveness, and chatter.

Spray pattern
Connect the tester as shown and, operating the pump lever in short, rapid strokes, observe the spray pattern. Pintle nozzles should produce a finely divided spray of uniform consistency and penetration (Fig. 5-24). Multi-hole nozzles generate a wide, fan-like pattern (Fig. 5-25). It can be helpful to direct the discharge against a piece of paper and compare the pattern to one produced by a new injector.