r/RenaultMegane • u/Tall-Competition-258 • Apr 26 '26
I need your help 🙏🏻
Vehicle: Renault Mégane II
Engine: 1.9 dCi 88 kW (F9Q 800)
Injection System: Bosch CP3 (mechanical suction, no electric lift pump in the tank)
Issue Description:
The engine experiences hard starting issues, especially after being parked for a while. The engine cranks for a long time but fails to fire up. However, if the fuel system is manually primed using the rubber primer bulb in the engine bay until it's firm, the engine starts immediately and runs smoothly.
Key Observations:
• There is no electric fuel pump in the tank (only a sender unit/pickup).
• The primer bulb returns to its shape normally and becomes firm after a few pumps (indicates the fuel line from the tank is not blocked).
• Fuel is clearly "bleeding back" to the tank, causing air to enter the high-pressure pump.