Fuel Line Pressure Inspection

WARNING:

Fuel line spills and leakage from the pressurized fuel system are dangerous. Fuel can ignite and cause serious injury or death and damage. To prevent this, complete the following inspection with the engine stopped.

Follow "BEFORE SERVICE PRECAUTION" before performing any work operations to prevent fuel from spilling from the fuel system. (See BEFORE SERVICE PRECAUTION ).
Disconnect the negative battery cable.
Disconnect the quick release connector (in the engine compartment). (See QUICK RELEASE CONNECTOR (FUEL SYSTEM) REMOVAL/INSTALLATION ).
Turn the lever of the SST parallel to the hose as shown in the figure.
Insert the SST quick release connector into the fuel pipe until a click is heard.
Verify that the quick release connector is firmly connected by pulling it by hand.
Start the fuel pump using the following procedure:

Fig 1: Checking Fuel Line Pressure
Courtesy of MAZDA MOTORS CORP.

Using M-MDS
1. Connect the M-MDS to the DLC-2.
2. Start the fuel pump using the "FP" simulation function.
  
  Fig 2: Identifying Data Link Connector 2
  Courtesy of MAZDA MOTORS CORP.
Without using M-MDS
1. Remove the fuel pump relay.
  CAUTION:
  - Be careful to short the specified terminal as shorting the wrong terminal of the main fuse block may cause a malfunction.
    
    Fig 3: Identifying Fuel Pump Relay And Main Fuse Block
    Courtesy of MAZDA MOTORS CORP.
2. Using a jumper wire, short fuel pump relay terminals C and D and connect the negative battery cable to start the fuel pump.
Operate the fuel pump for 10 s .
Measure the fuel line pressure.
- If not within the specification, inspect the following:
  If it less than the specification:
  - Fuel pump unit
  - Fuel line leakage
  If it exceeds the specification:
  - Pressure regulator
    
    Fig 4: Identifying Fuel Pump Relay Terminals
    Courtesy of MAZDA MOTORS CORP.
Fuel pressure (Reference)

350-410 kPa {3.57-4.18 kgf/cm ² , 50.8-59.4 psi}
Stop the fuel pump using the following procedure:
Using M-MDS
1. Stop the fuel pump using the "FP" simulation function.
Without using M-MDS
1. Disconnect the negative battery cable to stop the fuel pump.
Measure the fuel hold pressure after 5 min .
- If not within the specification, inspect the following:
  - Fuel line for clogging or leakage
Fuel hold pressure (Reference)

250 kPa {2.55 kgf/cm ² , 36.2 psi} or more
Disconnect the SST .
Connect the quick release connector. (See QUICK RELEASE CONNECTOR (FUEL SYSTEM) REMOVAL/INSTALLATION ).
Inspect all related parts by performing "AFTER SERVICE PRECAUTION". (See AFTER SERVICE PRECAUTION ).