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Chapter 4 Fuel System

(MR7131A, MR7151A, MR7161A)

Section 1 Check Fuel System Pressure

1. Remove the fuel tank from the vehicle

2. Check the fuel pump running

(a) Connect the positive and negative battery terminal to the concerned

fuel pump connector. See (Figure 91).

Notice: Do not start engine

The sound of fuel flowing can be heard if there is pressure.

Check fusible link, fuse, EFI open circuit relay, fuel pump, ECU and

wire connector if there is no pressure.

(b) Turn the ignition switch to "OFF" position.

3. Check fuel pressure

(a)  Check battery electrical pressure to be above 12V.

(b)  Detach negative terminal cable from the battery.

(c) Install pressure gage from the fuel delivery pipe. See (Figure 92).

(d) Connect battery negative terminal.

(e) Measure fuel pressure

Fuel pressure:

304-343kPa

Check fuel pipe & union, fuel pump, fuel filter if the pressure is too

low.

(f) Start engine. Measure fuel pressure at idle. Fuel pressure: 304-343kPa

(g) Check fuel pressure and retain the pressure for approximately 5min after the engine stopped.

Fuel pressure: 147kPa

Figure 91

Figure 92

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Section 2  Fuel Pump Inspection

1.  Fuel pump

(a) Check fuel pump resistance, 0.2~3.0

 at 20°.  Replace fuel pump if the resistance is not as specified.

See (Figure 93)

(b) Fuel pump running:

Check fuel pump by connecting with battery. Replace fuel pump or wire if the running is not as specified.

See (Figure 94).

The test should be conducted within 10s to prevent coil from damage.

2. Fuel injector assembly

Injection Volume: 40~50cm

3

/s

Error between each injector: less than 10 cm

3

Replace injector if the injection volume is not as specified.

(a) Check for leakage: Disconnect the cable from the battery. The fuel drop/min is no more than 1 drop.

Figure 93

Figure 94

Ohmmeter

Battery

Ω

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Section 3 Fuel Injector Replacement

1. Check fuel for ejection.

2. Remove PCV ventilation hoses. See (Figure 95). Remove fuel pipe clamp.

3. Detach fuel hose sub-assembly

4. Detach fuel delivery pipe sub-assembly. See (Figure 96)

(a) Press the connector to lock the spring and pull the connector from the injector.

(b) Remove 2 screws and detach fuel delivery pipe with injector.

5. Remove fuel injector assembly

6. Install injector assembly

(a) Smear a light layer of oil on two O-rings and install them to injector. See (Figure 97).

(b) Install 4 injectors to feul delivery pipe by rotating them left and right. See (Figure 98).

(c) Install retain frame to each injector.

Figure 95

Figure 96

Figure 97

Figure 98

New O-ring

Upward

Ratain Frame

Push

Rotate

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7. Install fuel delivery pipe sub-assembly

(a) Install two washers in intake manifold. See (Figure 99).

(b) Install 4 injectors and fuel delivery pipe assembly into intake manifold .

(c) Temperarily install 2 bolts to attach the fuel delivery pipe to intake

manifold .

(d) Check injector for smooth rotation. See (Figure 100).

Hint: If injector doesn't rotate smoothly, replace O-ring with the injector

connector upward.

(e) Tighten the 2 bolts and attach the fuel delivery pipe to intake manifold

See (Figure 101).

Torque: 15N. m

Figure 100

Figure 101

Figure 99

Washer

Rotate

Upward