FUEL PUMP TESTING AND CALIBRATION

TM 9-2815-225-34&P · Work Package 0044 00

PREADJUSTMENT CHECKS, IDLE SPEED ADJUSTMENT, HIGH-SPEED ADJUSTMENT, CHECKING AND ADJUSTING FUEL RAIL, CHECKING AND ADJUSTING ENGINE FUEL, CHECKING AND ADJUSTING THROTTLE LEAKAGE, CHECKING FUEL FILTER RESTRICTION,

FUEL PUMP SEAL INSTALLATION, THROTTLE SHAFT COVER PLATE INSTALLATION

INITIAL SETUP

Tools and Special Tools                                Materials/Parts
 General mechanic’s tool kit: automotive               Snapring (Item 1, Table 27, WP 0062 00)
    (Item 1, WP 0061 00)                               Gasket (Item 2, Table 27, WP 0062 00)
 Maintenance and repair shop equipment,                Throttle shaft cover plate
    automotive (Item 2, WP 0061 00)                      (Item 3, Table 27, WP 0062 00)
 Automotive maintenance and repair
    supplemental set no. 2 (Item 3, WP 0061 00)
 Fuel pump idle adjusting tool
    (Item 60, WP 0061 00)
 Throttle shaft ball installing tool
    (Item 61, WP 0061 00)
TM page 0044 00-2
WARNING Allow adequate ventilation for engine exhaust gases. Do not perform fuel system procedures while smoking or within 50 ft (15.2 m) of sparks or open flame. Diesel fuel is flammable and may explode. Failure to comply may result in serious injury or death to personnel.

PREADJUSTMENT CHECKS

CAUTION Do not alter pump settings to match gauges and tachometers of unknown accuracy. Failure to comply may result in damage to equipment. **NOTE** Vehicle fuel control lever and throttle stop linkage should have a maximum throttle stop, so when fuel pump full throttle is obtained, override pressure will not be on throttle shaft. After proper calibration, fuel pump should require very little adjustment. Some adjustment may be required at idle, since this setting is dependent on parasitic loads. Fine adjustment of governor settings and fuel manifold pressure is permissible within the limits specified if justified by engine performance tests. Check and adjust throttle control linkage for full throttle operation and throttle released operation with the throttle stopped by the throttle leakage adjusting screw.

IDLE SPEED ADJUSTMENT

NOTE Idle speed adjustment should never be made on a cold engine. Engine must be operated for sufficient time to purge all air from the fuel system and to bring the engine up to operating temperature (at least 165° F (74° C) oil temperature).

1. Remove plug (7) from spring pack cover (9) and start engine (1) on dynamometer (2).

NOTE Fuel pump idle adjusting tool will not let the spring pack cover leak when the idle is adjusted.

2. Turn idle adjusting screw (16) in to increase engine rpm, out to decrease rpm.

3. Using idle adjusting tool (4), set idle to 600 +/- 2 rpm.

4. Install plug (7) on spring pack cover (9).

TM page 0044 00-3
Figure 1. Idle Speed Adjustment.

HIGH-SPEED ADJUSTMENT

1. Remove spring pack cover (9), three captive washer screws (6), screw (8), and four washers (5) from fuel pump (3).

2. Remove fuel pump gasket (10) from fuel pump (3). Discard gasket (10).

3. Remove snapring (11) from fuel pump (3). Discard snapring (11).

4. Remove spring retainer (12) from fuel pump (3).

NOTE Each 0.0001 in. (0.025 mm) shim thickness will change speed approximately 2 rpm.

5. Add or remove shims (13) behind spring (14). High-speed adjustment should be 2130 to 2150 rpm.

6. Install spring retainer (12) and new snapring (11) on guide (15).

7. Install spring pack cover (9) and new gasket (10) on fuel pump (3) with three captive washer screws (6), screw (8), and four washers (5). Tighten screws (6) and (8) 9–11 lb-ft (12–15 N•m).

NOTE Do not use this check to make governor speed adjustments. If no-load speed is much greater than specifications, examine governor for malfunction or faulty parts.

8. Operate engine (1) to purge air from fuel system and bring up to operating temperature.

9. Bring engine (1) to full throttle and hold. Note maximum rpm. Speed should be 10–12 percent greater than governor speed cutoff point.

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3 4

16 8 15 5

13 11 Figure 1. Idle Speed Adjustment.

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CHECKING AND ADJUSTING FUEL RAIL

NOTE It should not be necessary to adjust fuel rail pressure on a newly calibrated fuel pump more than +/- 2 psi (+/- 14 kPa). If adjustments greater than this are required, fuel pump test stand, injector test stand, or engine problems may exist. Do not remove throttle shaft ball unless fuel rail pressure adjustment needs to be performed. The correct method of checking engine fuel rail pressure is with engine installed on a chassis or engine dynamometer.

1. Check governor speed cutoff and adjust if necessary.

2. Install fuel rail pressure gauge (4) between fuel supply elbow (11) on fuel pump assembly (10) and female union tee (12).

3. Bring engine (3) to full throttle load until rpm falls to rated speed.

4. Note fuel rail pressure gauge (4) reading. If pressure is above or below 83 psi, perform steps 5–8.

CAUTION Do not turn threaded stud out beyond maximum throttle travel. The fuel hole in the throttle shaft will begin to close. Never adjust fuel rail pressure above maximum specifications. This will void engine warranty and violate Environmental Protection Agency (EPA) requirements.

5. Turn threaded stud (9) out to obtain maximum throttle travel and secure with jamnut (8).

6. Remove throttle shaft ball (5) from throttle shaft (6).

NOTE It should not be necessary to adjust fuel manifold pressure on a newly calibrated pump more than +/- 2 psi (+/- 14 kPa). If adjustments greater than these are required, fuel pump test, injector test stand, or engine problems may exist.

7. Turn fuel adjusting screw (7) in throttle shaft (6) in to increase or out to decrease pressure while watching fuel rail pressure gauge (4).

8. Using throttle shaft ball installing tool (1), install throttle shaft ball (5) into end of throttle shaft (6).

TM page 0044 00-5
Figure 2. Fuel Adjustment.

CHECKING AND ADJUSTING ENGINE FUEL

1. Connect fuel pump (10) to fuel rate meter (2).

2. Bring engine (3) to full throttle and increase dynamometer load until engine rpm falls to rated speed.

3. Check governor speed cut-off while load is on engine (3).

4. Check fuel rail pressure gauge (4) at maximum speed.

5. Hold engine speed and load at maximum speed long enough for fuel rate meter (2) to stabilize.

NOTE The fuel rate specified on fuel pump calibration specification is at full throttle and rated speed. An engine or chassis dynamometer must be used. Accurate fuel rail pressure and speed readings must also be taken.

6. Verify correct fuel rate measurement with fuel rate meter (2).

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7 6

TM page 0044 00-6

CHECKING AND ADJUSTING THROTTLE LEAKAGE

NOTE If throttle leakage is adjusted correctly on fuel pump test stand, fuel pump will not need to be adjusted on engine. Vehicle throttle linkage must be adjusted so that threaded stud of throttle leakage adjusting screw (rear screw) just contacts stop in pump throttle. The purpose of the throttle leakage is to keep the fuel lines and injector drilling full of fuel during closed throttle operation. The correct throttle leakage will help acceleration when the throttle is opened after going down a grade. Throttle leakage will also prevent stalling when it slows down to the idle speed. Too much leakage will cause slow deceleration.

1. Bring engine (1) to full throttle and allow engine (1) to run at maximum no-load speed.

2. Release or move throttle quickly and start a suitable timer or stopwatch at the same time.

3. Stop timer when 1000 rpm is reached and check deceleration time. Repeat this check several times.

4. Increase leakage as engine (1) begins to stall (idle governor does catch engine after deceleration from high idle) by turning in threaded stud (3).

5. Recheck engine (1) deceleration until time is increased 1-2 seconds.

6. Lock threaded stud (3) with jamnut (2).

7. Recheck idle speed and readjust as necessary.

8. Bring engine to 1000 rpm.

TM page 0044 00-7
Figure 3. Checking and Adjusting Throttle Leakage.

CHECKING AND ADJUSTING THROTTLE LEAKAGE (Contd)

9. Check deceleration time when engine (1) is shut down.

10. Decrease leakage by turning threaded stud (3) out until engine (1) tends to stall after deceleration to high idle.

11. Turn in threaded stud (3) until deceleration is increased 1-2 seconds. Lock threaded stud (3) with jamnut (2).

12. Recheck idle speed and readjust as necessary.

NOTE Engine power cannot be set accurately in any other way except on engine dynamometer. Fuel pump adjustments must not be made on an engine when the engine power comes from an estimate. Before any adjustments on the fuel pump are made, the following engine performance data must be checked so that adjustments are justified.

13. Check fuel rail pressure, fuel rate, speed setting, smoke, coolant temperature, combustion smoothness, exhaust restriction, fuel quality, air intake restriction, engine oil level, and engine power reducing factors.

14. Check engine power by rechecking setting point of governor speed cutoff and readjust if necessary.

TM page 0044 00-8

CHECKING FUEL FILTER RESTRICTION

1. Connect vacuum gauge (3) to fuel inlet (4) on fuel damper (5).

2. Bring engine (1) to full throttle and full load on dynamometer (2) and check vacuum gauge (3).

3. If restriction reads 8 in. (20.3 cm) of vacuum while engine is running at full throttle and full load, change fuel filter and check other sources of restriction.

4. Use sight glass to check for moving bubbles and possible gasket or other leaks. If air bubbles are still seen, check float valve in float tank used for test. Fuel pump may be pumping more fuel than float valve will allow to pass into the float tank.

FUEL PUMP SEAL INSTALLATION

NOTE Fuel pump must be sealed after final adjustments are made to prevent tampering.

1. Using lockwire and seal (8), insert lockwire through screw (12), plug (11), and threaded stud (14) on spring pack cover (13).

2. Twist lockwires together until connection is secure and lockwire is tight.

3. Bend twisted lockwire into seal and press on top half of seal.

4. Using lockwire and seal (8), insert lockwire through screw (10), drilled fillister head screw (9), and captive washer screw (7).

5. Twist lockwires together until connection is secure and lockwire is tight.

6. Bend twisted lockwire into seal and press on top half of seal.

THROTTLE SHAFT COVER PLATE INSTALLATION

NOTE Use etching tool or steel stamp and imprint date of repair on backside of throttle shaft cover plate (6) for future reference.

1. Position new throttle shaft cover plate (6) on housing (16).

2. Drill two new holes on opposite sides of throttle shaft cover plate (6) 0.235 in. (5.969 mm) into pump housing (16).

3. Secure new throttle shaft cover plate (6) on housing (16) with two drive screws (15).

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Figure 4. Checking Fuel Filter Restriction. Figure 5. Fuel Pump Seal Installation.

Figure 4. Checking Fuel Filter Restriction.

Figure 5. Fuel Pump Seal Installation.

PDF page 404
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