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Fuel system components - check and renewal
Fuel and exhaust systems / Fuel system components - check and renewal


Warning: The fuel system pressure must be released before any part of the system is disturbed - see Section 2. Petrol is extremely flammable, so take extra precautions when you work on any part of the fuel system. Dont smoke, or allow open flames or bare light bulbs, near the work area. Dont work in a garage where a natural gas-type appliance (such as a water heater or clothes dryer) with a pilot light is present. If you spill any fuel on your skin, rinse it off immediately with soap and water. When you perform any kind of work on the fuel system, wear safety glasses, and have a Class B type fire extinguisher on hand.

Throttle housing
Check
1 Remove the plenum chamber (see Section 4), and verify that the throttle linkage operates smoothly.

2 If the housing bore and valve are dirty enough for you to think that this might be the cause of a fault, seek the advice of a Ford dealer. Do not clean the housing (see the notes in the checking procedure given in Section 15).

Renewal
3 Disconnect the battery negative (earth) lead - see Chapter 5, Section 1.

4 Remove the plenum chamber (see Section 4).

5 Disconnect the accelerator cable from the throttle linkage (see Section 5 or 6, as appropriate). Where fitted, also disconnect the cruise control actuator cable (see Chapter 12).

6 Releasing its wire clip, unplug the large electrical connector (next to the fuel pressure regulator). Similarly release and unplug the throttle potentiometers electrical connector.

7 Clearly label, then detach, all vacuum hoses from the throttle housing.

8 Remove the throttle housing mounting screws (see illustration), then detach the throttle housing and gasket from the inlet manifold. Discard the gasket - this must be renewed whenever it is disturbed.

16.8 Undo screws (arrowed) to remove throttle housing
16.8 Undo screws (arrowed) to remove throttle housing

9 Using a soft brush and carburettor cleaner, thoroughly clean the exterior of the throttle housing, then blow out all passages with compressed air.

Caution: Do not clean the throttle housings bore, the throttle valve, or the potentiometer, either by scraping or with a solvent. Just wipe them over carefully with a clean soft cloth.

10 Refitting is the reverse of the removal procedure. Fit a new gasket, and tighten the housing screws to the specified torque.

Fuel rail and injectors
Check
11 Refer to the procedure in the fuel system check (see Section 15).

Renewal
Note: For simplicity, and to ensure the necessary absolute cleanliness on reassembly, the following procedure describes the removal of the fuel rail assembly, complete with the injectors and pressure regulator, so that the injectors can be serviced individually on a clean work surface.

It is also possible to remove and refit an individual injector once the fuel system has been depressurised and the battery has been disconnected. If this approach is followed, read through the complete procedure, and work as described in the relevant paragraphs, depending on the amount of preliminary dismantling required. Be careful not to allow any dirt to enter the system (see illustrations).

16.12A Fuel injectors can be unbolted (arrowed) . . .
16.12A Fuel injectors can be unbolted (arrowed) . . .

16.12B . . . and removed individually if required, but it is better to remove
16.12B . . . and removed individually if required, but it is better to remove them with the fuel rail, if servicing is necessary. O-ring seals (arrowed) must be renewed whenever injector is removed

12 Relieve the residual pressure in the fuel system (see Section 2), and equalise tank pressure by removing the fuel filler cap.

Warning: This procedure will merely relieve the increased pressure necessary for the engine to run - remember that fuel will still be present in the system components, and take precautions accordingly before disconnecting any of them.

13 Disconnect the battery negative (earth) lead - see Chapter 5, Section 1.

14 Remove the plenum chamber (see Section 4).

15 If the additional clearance is required, disconnect the accelerator cable from the throttle linkage (see Section 5 or 6, as appropriate). Where fitted, also disconnect the cruise control actuator cable (see Chapter 12).

16 Releasing the wire clips, unplug the four fuel injector electrical connectors.

17 Disconnect the fuel feed and return lines at the quick-release couplings next to the braking system vacuum servo unit, then unclip the fuel hoses from the inlet manifold; use rag to soak up any spilt fuel. Note: Do not disturb the threaded couplings at the fuel rail unions unless absolutely necessary; these are sealed at the factory. The quick-release couplings will suffice for all normal service operations.

18 Disconnect the crankcase breather hose from the cylinder head cover union, and the vacuum hose from the fuel pressure regulator (see illustration).

16.18 Injector removal - disconnect fuel lines at quick-release couplings
16.18 Injector removal - disconnect fuel lines at quick-release couplings (A), unclip hoses (B), disconnect vacuum hose from regulator (C), unplug electrical connectors (D) - three of four shown - and disconnect breather hose from union (E)

19 Unscrew the three bolts securing the fuel rail, and withdraw the rail, carefully prising it out of the inlet manifold, and draining any remaining fuel into a suitable clean container (see illustrations). Note the seals between the rail noses and the manifold; these must be renewed whenever the rail is removed.

16.19A Unscrew bolts (arrowed) . . .
16.19A Unscrew bolts (arrowed) . . .

16.19B . . . and withdraw fuel rail with injectors and pressure regulator -
16.19B . . . and withdraw fuel rail with injectors and pressure regulator - renew nose seals (arrowed) whenever rail is disturbed

20 Clamping the rail carefully in a vice fitted with soft jaws, unscrew the two bolts securing each injector, and withdraw the injectors.

Place each in a clean, clearly-labelled storage container.

21 If you are renewing the injector(s), discard the old injector, the nose seal and the O-rings.

If you are simply renewing leaking injector O- rings, and intend to re-use the same injectors, remove the old nose seal and O-rings, and discard them.

22 Further testing of the injector(s) is beyond the scope of the home mechanic. If you are in doubt as to the status of any injector(s), it can be tested at a dealer service department.

23 Refitting is the reverse of the removal procedure, noting the following points: (a) Lubricate each nose seal and O-ring with clean engine oil on installation.

(b) Locate each injector carefully in the fuel rail recess, ensuring that the locating tab on the injector head fits into the slot provided in the rail. Tighten the bolts to the specified torque.

(c) Fit a new seal to each fuel rail nose, and ensure the seals are not displaced as the rail is refitted. Ensure that the fuel rail is settled fully in the manifold before tightening the three bolts evenly and to the torque wrench setting specified.

(d) Fasten the fuel feed and return quickrelease couplings as described in Section 3.

(e) Ensure that the breather hose, vacuum hose and wiring are routed correctly, and secured on reconnection by any clips or ties provided.

(f) On completion, switch the ignition on and off five times, to activate the fuel pump and pressurise the system, without cranking the engine. Check for signs of fuel leaks around all disturbed unions and joints before attempting to start the engine.

Fuel pressure regulator
Check
24 Refer to the fuel pump/fuel pressure check procedure (see Section 8).

Renewal
25 Relieve the residual pressure in the fuel system (see Section 2), and equalise tank pressure by removing the fuel filler cap.

Warning: This procedure will merely relieve the increased pressure necessary for the engine to run - remember that fuel will still be present in the system components, and take precautions accordingly before disconnecting any of them.

26 Disconnect the battery negative (earth) lead - see Chapter 5, Section 1.

27 Remove the plenum chamber (see Section 4).

28 Disconnect the vacuum hose from the regulator.

29 Unscrew the two regulator retaining bolts, place a wad of clean rag to soak up any spilt fuel, and withdraw the regulator (see illustration).

16.29 Disconnect vacuum hose, and unscrew bolts (arrowed) to withdraw fuel
16.29 Disconnect vacuum hose, and unscrew bolts (arrowed) to withdraw fuel pressure regulator

30 Refitting is the reverse of the removal procedure, noting the following points: (a) Renew the regulator sealing O-ring whenever the regulator is disturbed.

Lubricate the new O-ring with clean engine oil on installation.

(b) Locate the regulator carefully in the fuel rail recess, and tighten the bolts to the specified torque wrench setting.

(c) On completion, switch the ignition on and off five times, to activate the fuel pump and pressurise the system, without cranking the engine. Check for signs of fuel leaks around all disturbed unions and joints before attempting to start the engine.

Idle speed control valve Check
31 Disconnect the battery negative (earth) lead - see Chapter 5, Section 1.

32 Raise the front of the vehicle, and support it securely on axle stands.

Warning: Do not place any part of your body under a vehicle when its supported only by a jack!

33 Unplug the valves electrical connector (see illustration).

16.33 Access to idle speed control valve is from underneath vehicle - unplug
16.33 Access to idle speed control valve is from underneath vehicle - unplug electrical connector (arrowed) to check valve

34 Connect a 12-volt battery across the valves terminals - positive (+) to terminal 37 (the green/yellow wire) and negative (-) to terminal 21 (the black/yellow).

Caution: It is essential that the correct polarity is observed, or the diode incorporated in the valve may be damaged.

35 A distinct click should be heard each time contact is made and broken. If not, measure the resistance between the terminals. If the resistance is as specified, the valve is okay (but there may be a problem with the wiring or the ECU). If the resistance is not as specified, renew the valve (see below).

36 Plug in the valves electrical connector.

Renewal
37 Disconnect the battery negative (earth) lead - see Chapter 5, Section 1.

38 Raise the front of the vehicle, and support it securely on axle stands.

Warning: Do not place any part of your body under a vehicle when its supported only by a jack!

39 Unplug the valves electrical connector.

40 Unscrew the two retaining bolts, and withdraw the valve from the inlet manifold (see illustration).

16.40 Unscrew bolts (arrowed) to remove idle speed control valve
16.40 Unscrew bolts (arrowed) to remove idle speed control valve

41 Since the valves individual components are not available separately, and the complete assembly must be renewed if it is thought to be faulty, there is nothing to be lost by attempting to flush out the passages, using carburettor cleaner or similar solvent. This wont take much time or effort, and may well cure the fault.

42 Refitting is the reverse of the removal procedure, noting the following points: (a) Clean the mating surfaces carefully, and always fit a new gasket whenever the valve is disturbed.

(b) Tighten the bolts evenly and to the specified torque wrench setting.

(c) Once the wiring and battery are reconnected, start the engine and allow it to idle. When it has reached normal operating temperature, check that the idle speed is stable, and that no induction (air) leaks are evident. Switch on all electrical loads (headlights, heated rear window, etc), and check that the idle speed is still correct.

Idle-increase solenoid valve Check
43 If this valve is thought to be faulty, unplug its electrical connector and disconnect its vacuum hoses, then connect a battery directly across the valves terminals. Check that air can flow through the valves passages when the solenoid is energised, and that nothing can pass when the solenoid is not energised.

Alternatively, connect an ohmmeter to measure the resistance between the valves terminals, and compare this reading to that listed in the Specifications Section at the beginning of this Chapter. Renew the valve if it is faulty (see illustration).

16.43 Location of idle-increase solenoid valve (A) and diode (B)
16.43 Location of idle-increase solenoid valve (A) and diode (B)

44 The solenoids diode is fitted to control any voltage spikes which might occur as the solenoid is switched off. A faulty diode would not, therefore, necessarily interfere with the operation of the valve. If the diode is thought to be faulty, however, it can be checked by unplugging it and connecting an ohmmeter across its terminals, to check that continuity exists in one direction only. If continuity is found in both directions, or in neither, the diode is faulty, and must be renewed.

Renewal
45 If better access is required, remove the plenum chamber (see Section 4).

46 Disconnect the battery negative (earth) lead - see Section 1 of Chapter 5.

46 Unplug the valves electrical connector.

Unclip the valve from the bulkhead, then disconnect its vacuum hoses and withdraw it.

47 Refitting is the reverse of the removal procedure.


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