To perform a quick check on the mechanical pump in carburetor-equipped vehicles, first, disconnect the negative battery terminal, then remove the air cleaner assembly. Next, detach the fuel inlet fitting from the carburetor and place the inlet line end in a container. Reconnect the battery terminal and, if available, use a remote starter switch per manufacturer's instructions; if not, you'll need an assistant. Disable the ignition coil by detaching the primary lead wires, and with the fuel line directed into the container, have your assistant turn the ignition key to Start and crank the engine for about ten seconds. Observe well-defined spurts of fuel emission; if not, there's a fuel delivery issue. For a pressure test, employ a fuel pressure gauge, hose restrictor, and flexible hose, connecting them between the fuel inlet fitting or fuel filter and the carburetor. Start the engine, discharge fuel into a container briefly, close the restrictor, and note the pressure, which should be 4-to-5 psi for four-cylinder and 6-to-7.5 psi for V6 engines. If pressure is incorrect and fuel lines are fine, replace the pump. For a capacity test, operate the engine at idle, discharge fuel into a container for 30 seconds, and ensure at least one pint of fuel is discharged. If not, repeat with an auxiliary fuel supply and replace the fuel filter for four-cylinder engines if necessary. If volume is good, check the fuel supply line for blockage. V6 engines can undergo a direct connection vacuum test using a vacuum gauge, while an indirect connection vacuum test can be performed with a T-fitting. If vacuum isn't within specification, the pump is defective. On fuel-injected vehicles with electric pumps, perform a TBI pressure test by replacing the pressure test port plug with a special fitting, attaching a 0-to-30 psi fuel pressure gauge, and adjusting pressure with the regulator screw. For MPI pressure tests on earlier models, use a 0-to-60 psi gauge on the fuel rail and note pressure with and without vacuum to check the regulator. Later models require a special fixture. To test for fuel pressure leak down, use a gauge capable of reading 0-to-100 psi, start the engine, check pressure, shut down, and monitor pressure for 30 minutes; a drop of 0-to-20 psi is acceptable. If it exceeds, perform additional tests to identify the issue and replace the regulator or pump accordingly.
Posted by MoparPartsGiant Specialist 
