Buick 25168719 Fuel Pump

The fuel pump is a sealed type actuated from the engine camshaft, utilizing a pushrod between the camshaft and the pump rocker, while 231 V6 engines have pumps driven directly from the camshaft eccentric without a pushrod. Servicing is not possible due to the sealed nature of the unit, but if a fault is suspected, a test can be performed. First, ensure there is gas in the fuel tank and disconnect the primary wire between the coil and the distributor to prevent engine firing when the starter motor is engaged for models from 1969 to 1974; for models from 1975 to 1981, disconnect the distributor wiring marked 'BAT'. Next, disconnect the fuel line from the carburetor and place its open end in a container. Finally, operate the starter motor and observe for well-defined spurts of fuel ejected from the open end of the line; if present, the pump is functioning correctly, otherwise, it should be replaced.

To take out the pump you need to unscrew the fuel inlet and outlet that should be done with a two wrenches approach in order to avoid severe harm on the pump and other connections. Fourthly, remove the fuel pump mounting bolts, the fuel pump, as well as the gasket provided. In the course where pushrod is required to be removed, then first remove the pipe plug or the pump adapter and the gasket if fitted. In the installation process of the pushrod, put the gasket sealant on the pipe plug or the gasket of the component, and fasten it in place with some heavy grease not applicable on the V6 engines. Place the new gasket then fit the pump as it located in the 231 V6 engine while the protruding part of the fuel pump's rocker arm depresses the camshaft, apply gasket sealant round the screw thread. Last of all, reattach the fuel lines, switch on the ignition and look for any dripping.

To remove the fuel pump/sending unit assembly, start by disconnecting the cable from the negative battery terminal. Then, relieve the fuel pressure. Next, remove the fuel tank. Inside the fuel tank, the fuel pump/sending unit assembly is held in place by a lockring mechanism. To unlock it, turn the inner ring clockwise until the locking cams are free of the retaining tangs. If the rings are too tight, gently knock them loose with a soft-face hammer. Carefully extract the fuel pump/sending unit assembly from the fuel tank, making sure not to bump it into the outer lockring. Inspect the condition of the rubber gasket and replace it if necessary. Also, inspect and clean the strainer on the lower end of the fuel pump. If needed, separate the fuel pump from the sending unit by pulling the pump assembly into the rubber connector and sliding it away from the bottom support. Take care not to damage the rubber insulator and fuel strainer. For installation, insert the fuel pump/sending unit assembly back into the fuel tank and turn the inner lockring counterclockwise until the locking cams are fully engaged by the retaining tangs. Finally, reinstall the fuel tank.

The fuel pump is located in the fuel tank for both four-cylinder and V6 models and is non-repairable. When the key is turned on, the ECM activates the fuel pump relay for quick pressure buildup. If not started, the ECM waits for engine start, using the oil pressure switch as a backup if the relay fails. A malfunctioning relay may cause long cranking times. The ECM powers the fuel pump when ignition is on, relying on HEI distributor pulses. To test the pump, install a fuel pressure gauge and turn ignition on. If no pressure, check the fuse and wiring. For a good fuse but no pressure, test the pump by applying battery voltage. Inspect the system for pressure discrepancies, leaks, and faulty components, including the relay and connector.

After cleaning the block mounting surface and applying grease to the pushrod, the new gasket and pump should be installed and the hoses and lines should be reattached.

Adjust the pump location if necessary by loosening the bracket screw and turning the pump.

Fuel flows to the carburetor when the outlet line pressure is less than that maintained by the diaphragm spring.

If fuel pressure is too low, you should conduct a fuel pump volume check, and if volume is insufficient, inspect for fuel line restrictions. If no restrictions are found, replace the fuel pump.

To begin, disconnect the negative battery cable to isolate the battery.

Inspect the condition of the seal around the mouth of the lockring mechanism.

Check for restrictions in fuel lines and filters, and inspect the fuel pump for issues.

Start by inspecting all fuel lines for leaks.

Ensure that there is enough fuel in the tank and relieve the fuel pressure.

First, 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 assembly, turn the lockring counterclockwise with a hammer and a brass punch. It's important not to use a steel punch to avoid sparking and the risk of an explosion. Carefully extract the fuel pump/sending unit assembly from the tank, taking care not to bump the fuel level float and sending unit into the lockring during removal to avoid affecting the accuracy of the sending unit.

The first step is to relieve the fuel system pressure and disconnect the cable from the negative battery terminal.

For V6 models, remove the pushrod.

The final step is to reconnect the fuel pipes, start the engine, and check for any leaks.

The first step is to relieve the fuel system pressure and disconnect the cable from the negative battery terminal.

There may be a leaking injector or a faulty fuel pump.

On V6 models, the fuel pump is located on the left-front side of the engine, while on V8 models, it is found on the right-front side.

For fuel-injected models, start by verifying that the fuel pump is running by listening for a whirring noise when the ignition switch is turned on. If the pump does not come on, check the fuel pump fuse and relay. If they are both functioning properly, check for an open circuit between the relay and the fuel pump. If the circuit is fine, disconnect the electrical connector at the fuel pump and connect battery voltage to the gray wire terminal of the pump to see if the pump runs.

Turn the inner ring counterclockwise until the locking cams are free of the tangs. If necessary, a hammer and brass punch can be used to tap the lock-ring counterclockwise, but avoid using a steel punch to prevent sparks that could cause an explosion.

After cleaning the block mounting surface and applying grease to the pushrod, the new gasket and pump should be installed and the hoses and lines should be reattached.

If no spurts are present, replacement of the pump is necessary.

If the pressure exceeds specifications, check the fuel return line and replace the pressure regulator if necessary.