Bench test Vacuum on fuel pump

[cas3]

When you buy a new pump at the store, they sometimes come with instructions stating that you should not move the arm by hand, as you may push too far and damage the diaphragm. Keep in mind that in use, on the motor, the arm really does not move very far. So me, being the kind that reads the directions after I screwed something up, would always pump the lever by hand with a finger over the inlet and you definitely should feel it suck. did you try that?