Post-Filter Service Validation and Priming Checklist
After every filter or separator service, complete the validation checklist — seals, prime, pressure, aeration — before releasing the vehicle.
Fault Overview
System checklist for validating the low-pressure fuel system after any filter, module, or separator service to prevent comebacks from air locks, leaks, or incomplete priming.
Engine & Platform Coverage
Symptoms
- •After filter change checklist
- •Post filter service validation
- •Priming validation standard
- •No start after filter service prevention
Possible Causes
- 1.N/A — process checklist. Common post-service failures are air locks, damaged seals, incorrect filters, and incomplete priming.
Wiring & Circuit Notes
Confirm no connectors were contaminated with fuel during service and that WIF/heater connectors are fully seated.
DVOM Specs & Sensor Tests
Supply pressure after priming. Aeration sight-glass confirmation. WIF status. Lift pump operation during prime. No external leaks.
Diagnostic Flow — FSM Sequence
AI Diesel Tech enforces this evidence-gate sequence. Each gate must pass before advancing.
8 steps locked behind Technician Mode- 1Step 1 — Confirm Correct Filters and Seals: Confirm correct filters and all new seals installed and lubricated per OEM. An incorrect filter or dry seal is the most common cause of post-service leaks.
- 2Step 2 — Verify Drain Valve is Closed and Sealed: Verify drain valve is closed and sealed. A partially open drain valve causes aeration.
- 3Step 3 — Perform OEM Priming Procedure Completely: Perform OEM priming procedure completely. Do not skip steps or stop early.
- 4Step 4 — Confirm Lift Pump Runs During Prime: Confirm lift pump runs during prime if applicable. Verify enable circuit is active.
- 5Step 5 — Check for External Leaks: Check for external leaks at all service points — housing, bowl, drain valve, and any disturbed fittings.
- 6Step 6 — Perform Quick Aeration Observation: Perform quick aeration observation with a clear sight glass or by observing the return line.
- 7Step 7 — Measure Supply Pressure During Crank and Idle: Measure supply pressure during crank and idle. Confirm pressure meets OEM minimum.
- 8Step 8 — Clear Codes and Verify No False WIF Codes: Clear any residual codes and verify no WIF false codes from the service.
- 9Step 9 — Road Test and Recheck Under Load: Road test and recheck pressure under load if possible. Only then release the vehicle.
Unlock the full evidence-gated diagnostic sequence, DVOM test steps, and repair procedures in Technician Mode.
Full Diagnostic Access
Verification steps, preventative measures, severity guidance, and legacy comparison are available in Technician Mode.
Typical Repair Costs
Complete any missed priming or seal steps — minimal cost. Correct leaks $30–150. Address residual air — no parts cost.
Start Diagnosing This Fault Now
AI Diesel Tech walks you through every evidence gate in the correct order. Choose the plan that fits your shop.
AI Diesel Tech — The Technician's Diagnostic Engine
AI Diesel Tech diagnostic logic is built by an ASE Certified Diesel Technician and engineered for professional shop use. Trusted by technicians nationwide — used in shops, fleets, and training programs.
Summary
Use the AI Diesel Tech diagnostic engine to run this code through a structured, evidence-gated sequence and get a confirmed root cause before any parts are replaced.