How the system works
A high-level system map. Component roles and exact circuit behavior vary by vehicle.
- 01Storage and ventingFuel is stored and vented safely
- 02Pressure generationA pump creates delivery pressure
- 03Fuel deliveryLines and filtration carry fuel
- 04Fuel meteringInjectors meter commanded quantity
- 05Mixture feedbackFeedback 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 componentCarry and regulate delivery
System contextStore fuel while controlling vapor release
System contextSupport closed-loop correction
Open componentSymptom patterns and first direction
Cranks but will not start
Confirm whether fuel delivery is actually missing before replacing a pump.
Follow the diagnostic pathSYMPTOMLean code or hesitation
Use fuel trims and operating pattern to separate unmetered air, delivery, measurement, and exhaust effects.
Follow the diagnostic pathSYMPTOMFuel odor or visible leak
Stop sources of ignition, move away, and arrange safe inspection.
Follow the diagnostic pathA system-level diagnostic method
Treat odor or leakage as the first safety decision
Capture codes, freeze-frame, trims, load, and temperature
Inspect electrical supply and external condition
Test pressure or delivery only with approved equipment
Verify command, injector, air, and mechanical evidence before replacement
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.