Home Tips & Tricks 2001 Dodge Pickup R1500 LEAK DETECTION PUMP (LDP) OPERATION AND DIAGNOSIS

2001 Dodge Pickup R1500 LEAK DETECTION PUMP (LDP) OPERATION AND DIAGNOSIS

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Download The evaporative emission system is designed to prevent the escape of fuel vapors from the fuel system. Leaks in the system, even small ones, can allow fuel vapors to escape into the atmosphere. Government regulations require onboard testing to make sure that the evaporative (EVAP) system is functioning properly. The leak detection system tests for EVAP system leaks and blockage. It also performs self-diagnostics. During self-diagnostics, the Powertrain Control Module (PCM) first checks the Leak Detection Pump (LDP) for electrical and mechanical faults. If the first checks pass, the PCM then uses the LDP to seal the vent valve and pump air into the system to pressurize it. If a leak is present, the PCM will continue pumping the LDP to replace the air that leaks out. The PCM determines the size of the leak based on how fast/long it must pump the LDP as it tries to maintain pressure in the system. EVAP LEAK DETECTION SYSTEM COMPONENTS (FIGURE 1) Service Port : Used with special tools like the Miller Evaporative Emissions Leak Detector (EELD) to test for leaks in the system. EVAP Purge Solenoid : The PCM uses the EVAP purge solenoid to control purging of excess fuel vapors stored in the EVAP canister. It remains closed during leak testing to prevent loss of pressure. EVAP Canister :