Diesel Data: Automotive Repair

Fuel System Pressure Relief

TOOLS REQUIRED
J34730-1A Fuel Pressure Gauge

CAUTION: Remove the fuel tank cap and relieve the fuel system pressure before servicing the fuel system in order to reduce the risk of personal injury. After you relieve the fuel system pressure, a small amount of fuel may be released when servicing the fuel lines, the fuel injection pump, or the connections. In order to reduce the risk of personal injury, cover the fuel system components with a shop towel before disconnection. This will catch any fuel that may leak out. Place the towel in an approved container when the disconnection is complete.

CAUTION: Refer to Battery Disconnect Caution in Service Precautions.




1. Disconnect the negative battery cable in order to avoid possible fuel discharge if an accidental attempt is made to start the engine.
2. Loosen the fuel filler cap in order to relieve the tank vapor pressure.
3. Remove the engine cover.
4. Connect a J 34730-1A, or the equivalent, to the fuel pressure connection.
5. Wrap a shop towel around the fitting while connecting the gauge in order to avoid spillage.
6. Install the bleed hose into an approved container and open the valve in order to bleed the system pressure. The fuel connections are now safe for servicing.
7. Drain any fuel remaining in the gauge into an approved container.