How the system works
Follow energy, material, information, and mechanical force through the system before focusing on a single component.
A high-level system map. Component roles and exact circuit behavior vary by vehicle.
- 01InputFuel is stored and vented safely
- 02Flow 2A pump creates delivery pressure
- 03Flow 3Lines and filtration carry fuel
- 04Flow 4Injectors meter commanded quantity
- 05Protect / verifyFeedback helps the engine controller correct mixture
Follow the sequence, stop when evidence changes the path, and verify the exact vehicle information before acting.
- 01Fuel is stored and vented safely
- 02A pump creates delivery pressure
- 03Lines and filtration carry fuel
- 04Injectors meter commanded quantity
- 05Feedback helps the engine controller correct mixture
Major components in context
Move fuel and often support level sensing
System contextMeters fuel into the intake or cylinder
Open component →Carry and regulate delivery
System contextStore fuel while controlling vapor release
System contextSupport closed-loop correction
Open component →Symptom patterns and first direction
Cranks but will not start
Confirm whether fuel delivery is actually missing before replacing a pump.
Follow the diagnostic path →SYMPTOMLean code or hesitation
Use fuel trims and operating pattern to separate unmetered air, delivery, measurement, and exhaust effects.
Follow the diagnostic path →SYMPTOMFuel odor or visible leak
Stop sources of ignition, move away, and arrange safe inspection.
Follow the diagnostic path →A system-level diagnostic method
Treat odor or leakage as the first safety decision
Use the result to support or reject a cause group before moving to a more invasive test.
Capture codes, freeze-frame, trims, load, and temperature
Use the result to support or reject a cause group before moving to a more invasive test.
Inspect electrical supply and external condition
Use the result to support or reject a cause group before moving to a more invasive test.
Test pressure or delivery only with approved equipment
Use the result to support or reject a cause group before moving to a more invasive test.
Verify command, injector, air, and mechanical evidence before replacement
Use the result to support or reject a cause group before moving to a more invasive test.
Evidence worth preserving
Operating-condition pattern
Fuel-trim and sensor relationships
Controlled pressure or delivery result
Injector command and contribution evidence
Use the VIN, installed equipment, current manufacturer information, and applicable safety rules.
Safety and professional boundary
Flammable fuel and vapor
Fuel and vapor can ignite from sparks, heat, static, or open flame. Relieve pressure and contain fuel only with the exact approved procedure and equipment.