How to Measure the Fuel Pressure in a 1996 Dodge 3.9
- 1). Raise the hood on the vehicle on which you are performing the fuel pressure test. Set the hood prop to hold the hood during this project, if one is available.
- 2). Visually inspect and locate the fuel rail on the driver's side of the 3.9-liter engine. Locate the pressure testing port on the fuel rail. The tester port has a cap on it that is identical to a tire valve stem cap. Remove the pressure tester protective cap by turning it counterclockwise with your hand.
- 3). Install a fuel pressure tester onto the fuel pressure testing port. Fasten the tester fitting onto the port by turning it clockwise by hand. Ask an assistant or second person to turn the engine of the vehicle on, while you hold the pressure tester gauge away from the engine. If the engine does not start, ask your assistant to turn the ignition key so that the engine turns over. Instruct your assistant not to turn the key for longer than 3 second intervals, as you will destroy the engine starter by doing so.
- 4). Read the dial gauge on the pressure tester to see how much fuel pressure the 3.9-liter is putting out. The gauge should be between 44 and 54 p.s.i. or pounds per square inch. If the engine is running and the number on the gauge is outside of the given parameters, then there is an issue with the fuel pressure in the engine.
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