Q: How to remove and install a fuel pump/sending unit assembly on a Chevrolet C1500 and K1500 equipped with dual fuel tanks?
A: On later model vehicles equipped with dual Fuel Tanks, a balance pump is used to connect the two tanks. This pump operates at about 7 psi and fills the front tank as needed from the rear. It is located on the left frame rail. Disconnect the cable from the negative battery terminal. Caution: On models equipped with the Theftlock audio system, be sure the lockout feature is turned off before performing any procedure which requires disconnecting the battery. Relieve the fuel pressure and remove the fuel tank. The fuel pump/sending unit assembly is located inside the fuel tank and is held in place by a cam lockring mechanism. To unlock the fuel pump/sending unit assembly, turn the lockring counterclockwise with a hammer and a brass punch. Warning: DO NOT use a steel punch to knock the lockring loose. A spark could cause an explosion. Carefully extract the fuel pump/sending unit assembly from the tank. Caution: The fuel level float and sending unit are delicate. Don't bump them into the lockring during removal or the accuracy of the sending unit may be affected. Check the condition of the seal around the mouth of the lockring mechanism. If it's dried out, cracked or deteriorated, replace it. Inspect the strainer on the lower end of the fuel pump. If it's dirty, remove it, clean it with solvent and blow it out with compressed air. If it's too dirty to be cleaned, replace it. If you have to separate the fuel pump and sending unit, pull the fuel pump into the rubber connector and slide the pump away from the bottom support. Care should be taken to prevent damage to the rubber insulator and fuel strainer during removal. After the pump clears the bottom support, pull it out of the rubber connector for removal. Insert the fuel pump/sending unit assembly into the fuel tank. Turn the lockring clockwise until the locking cam is fully engaged by the retaining tangs. The remainder of installation is the reverse of removal. Disconnect the fuel lines and electrical connectors from the fuel pump module. While prying the locking tab out, rotate the fuel pump module retaining ring counterclockwise until it's loose. Remove the fuel pump module from the tank. Angle the assembly slightly to avoid damaging the fuel level sending unit float. Warning: Some fuel may remain in the module reservoir and spill as the module is removed. Have several shop towels ready and a drain pan nearby to place the module in.
Q: How to check the Fuel Pump for Chevrolet K1500 and C1500?
A: If there is suspected insufficient fuel delivery, start by inspecting all fuel lines for leaks. Have an assistant turn the ignition switch to the ON position while listening for the fuel pump's "whirring" sound. If no sound is heard, check the fuel pump relay, fuses, and wiring. If power is present at the fuel pump connector and it still doesn't operate, replace the fuel pump. For the pressure check, use a fuel pressure gauge with the appropriate fittings. Relieve fuel pressure and install the gauge. Turn the ignition key On to observe the pressure reading, comparing it to the specified value. If the pressure is low, check for restrictions in fuel lines and filters, and inspect the fuel pump for issues. If the pressure is high, inspect the fuel return line for restrictions and replace the fuel pressure regulator if necessary. Start the engine and ensure the pressure is 3 to 10 psi below the previous reading. Monitor the pressure for five minutes after shutting off the engine; if it drops significantly, there might be a leak in the fuel line or injectors, or a defective fuel pump module check valve.