Compare injector commands with fuel-system pressure, delivered fuel, and mixture feedback.
Distinguish fuel pressure from fuel volume and injector command; compare idle and load conditions; interpret simulated rail pressure, injector pulse width, and fuel trim together; and select a next diagnostic test supported by evidence.
Illustrative gasoline port-injection teaching model with a fixed-pressure rail. The nominal 380 kPa value and all fault responses are examples, not specifications. Direct-injection systems, returnless controls, pressure regulators, and actual scan-tool behavior differ by vehicle. Follow OEM procedures and fuel-system safety precautions for real testing.
The command slider represents an illustrative ECM request. It does not directly control the pump or repair a mechanical restriction.
The arrows show a conceptual delivery path. A gauge reading alone does not measure the system’s available fuel volume under load.
Change the fault and operating condition. A system may maintain pressure at idle but fail to supply enough fuel at high load.