Q: How to replace a fuel pump module in a Chevrolet Colorado and GMC Canyon?
A: Relieve the fuel system pressure. Disconnect the cable from the negative battery terminal. Remove the Fuel Tank from the vehicle. Disconnect the fuel lines and EVAP line from the fuel pump module. Rotate the fuel pump module retaining ring counterclockwise until it's loose. A special tool (J45722) is useful for this operation. Note: Some module retaining rings may be marked "Do Not Reuse," but the manufacturer says that the rings may be reused as long as they are not corroded, bent or otherwise damaged. Remove the fuel pump module from the tank and drain the fuel from the reservoir. Angle the assembly slightly to avoid damaging the fuel level sending unit float. The electric fuel pump is not serviced separately. In the event of failure, the complete assembly must be replaced. Transfer the fuel pressure sensor and fuel level sending unit to the new fuel pump module assembly, if necessary. Clean the fuel tank sealing surface and install a new seal on the fuel pump module. Install the fuel pump module, aligning the fuel line fittings with the fuel lines. Press the fuel pump module down until seated and install the retaining ring. Make sure the retaining ring is fully seated and the locking tab is engaged with the slot. The remainder of installation is the reverse of removal.
Q: How to check fuel pump operation and fuel pressure?
A: To avoid fire, start with a preliminary check to see if there is any leakage of fuel line. An assistant should then turn the ignition switch to ON while listening for a whirring noise which will indicate that the fuel pump is working; in case no sound is heard, a person should also go ahead and inspect the fuel pump fuse and relay and control circuit to the PCM. If no pump operation still exists, remove the electrical connector of the fuel pump module and check for power and ground. On finding out that there is absent power or ground, repair the wiring. In case there is power but the pump does not run, replace this part. To carry out pressure check use a fuel pressure gauge after relieving fuel pressure first. Next attach this gauge to a test port and cycle ignition key to note down pressure reading repeatedly until obtaining maximum reading value. For 2004 and 2005 models install a shut off valve if pressure is low; check return line for restrictions if high but not found then replace Fuel Pressure Regulator. While engine is running at least initial readings of 3-10 psi lower than those will be noticed upon further inspection revealing lack of vacuum at fuel pressure regulator whereupon it should be replaced if it fails to reduce pressure despite its presence in such cases or not. For 2006 models onwards however this can be understood by checking whether the vacuum at fuel pressure regulator lowers when it reduces down or not makes sense given what we know of how things work together at these higher levels before ending up back where we started again which coincidentally also happens every time someone looks into what has been done since their last visit here too so maybe someday soon we might get somewhere other than here though even though it seems like nothing ever changes around here anymore anyway While engine is running in 2006 model vehicles, variation of pressure can be checked through similar troubleshooting steps as previously explained above Finally, check how much drop in fuel pressure there is for the next five minutes after engine has been turned off to ensure that the level does not reduce by over 5 psi. Some of the potential causes include leaking fuel line, Fuel Injector which is leaking, or problem in regulator or check valve of fuel pump module that can be verified by cutting off vacuum line and inspecting presence of fuel.