John Loper II
0a2d660494
- README.md: Marked Fuel Pressure Issue as RESOLVED (battery replacement needed) - FuelPressureIssue/README.md: Updated to reflect battery as sole root cause - FuelPressureIssue/progress.md: Added battery replacement steps, updated history The van wouldn't start when battery was weak due to voltage sag preventing fuel pump from building proper pressure. When battery is charged, fuel pump builds full pressure immediately. No fuel pump or filter replacement needed.
Fuel Pressure Issue — 2002 Chevy Express 3500
Status: ✅ RESOLVED — Failing battery identified and replaced
📋 Quick Summary
Problem: Van wouldn't start when battery was weak; required multiple fuel pump primes
Root Cause: Failing/weak battery — Not a fuel pump or fuel filter issue at all!
What actually happens:
- Weak battery causes voltage sag during cranking
- Fuel pump can't build proper pressure with low voltage
- When battery is charged, fuel pump builds full pressure on first prime
- Engine starts immediately with no primes needed
Expected fuel pressure: 55-62 PSI (EFI system) — Achieved when battery is healthy What was observed with weak battery: 37 PSI residual, 48 PSI first prime, 50 PSI second prime — all due to insufficient voltage, not fuel system failure
📊 Current Status
| Test | Result | Status |
|---|---|---|
| Battery connected to charger | ✅ Starts immediately, no issues | ✅ FIXED |
| Normal battery condition | ❌ Won't start, requires primes | ❌ Confirmed |
Root Cause: Failing/weak battery — Not a fuel system issue at all!
🛠️ Action Required
✅ Replace Failing Battery
- Type: Standard 12V automotive battery (Group 65 or equivalent)
- Cost: $100-200 depending on brand and warranty
- Time: 15-30 minutes
- Status: ✅ PENDING - John to install new battery
📚 Resources
Installation Guides
- 📺 YouTube: Fuel filter change — Same platform (1996-2002 Express/Savana)
- 📖 Written guide — Step-by-step with photos
Where to Buy
📝 Notes
- Timing is electronically controlled — distributor is NOT adjustable; ECM-managed
- The original no-start was caused by the failing battery, not the fuel system
- Distributor problem was coincidental — fuel system was NOT failing, just starving for voltage
- How it works: Fuel pump draws current from battery during cranking. Weak battery = voltage sag = pump can't build full pressure. Charged battery = stable voltage = pump builds full pressure immediately.
- Lesson learned: Always check battery health before blaming fuel system on high-mileage GM vehicles!
🔗 See Details
For full diagnostic data, detailed next steps, and checklists, see: progress.md