Using the 4C6821 Injection Line Speed Pickup Group{0781} Caterpillar

Introduction

The 4C6821 Injection Line Speed Pickup Group provides a method of sensing engine speed through the fuel injection lines without disconnecting any of the injection lines. The pickup group can be clamped onto any fuel injection line. The pickup group is then connected to the PH (Photo) input of a 6V2100 Multitach with the cable provided. The multitach then displays the engine speed in R/MIN (rpm). The accuracy of measurement is the same as the original specification for the multitach (± 1 R/MIN). Refer to the NOTE below.

NOTE: Modifications must be made to some earlier 6V2100 Multitachs before speed measurements can be taken accurately. Refer to the topic "Modification of 6V2100 Multitach" for this procedure, and to determine if modifications are necessary.

The pickup group can be easily installed on any fuel injection line. The only preparation necessary is the removal of a small amount of paint from the injection line where the pickup group is to be clamped. The injection line speed pickup group can be used either for temporary testing or for permanent installation.

* The 4C6821 Pickup Group is a direct replacement for the 6V4950 Injection Line Speed Pickup Group.

The 4C6821 Pickup Group differs from the 6V4950 Injection Line Speed Pickup Group only by the inclusion of a switch on the 4C6812 Amplifier and use of the newer 1U9139 Universal Style Pickup. The switch adapts the amplifier for use with the 4C6800 Data Logger Group. When used with the 6V2100 Multitach, the switch should always be in the INJ LINE position.

4C6821 Injection Line Speed Pickup Group Components

(1) 1U9139 Pickup. (2) 4C6812 Amplifier.

Reference: Special Instructions SMHS7504-01, SEHS7807 and SEHS8224.

Modification of 6V2100 Multitach

Check the 6V2100 Multitach;

* If there is an "A" at the location shown, no modifications are needed.

* If there is no "A", Refer to Special Instruction SEHS8224, entitled "Troubleshooting and Repair of the 6V2100 Multitach", for the update modifications needed.

These modifications if needed, must be made to the multitach to achieve the correct accuracy of the speed readings.

Optional Items for Use With the 4C6821 Injection Line Speed Pickup Group

(1) 6V2100 Multitach. (2) 6V4190 Autoprogrammer. (3) 5P7366 Power Cable. (4) 6V2198 Extension Cable.

The 6V2100 Multitach (1) is a programmable digital tachometer used as the speed readout for the injection line speed pickup group.

The 6V4190 Autoprogrammer (2) is an accessory for the 6V2100 Multitach, which provides automatic programming whenever the multitach is powered and when switching between PH (photo) and MAG (magnetic) inputs.

The 5P7366 Power Cable (3) is used for connecting 11-40 VDC power to the multitach.

The 6V2198 Extension Cable (4) is the photo input extension cable, used for connecting the 6V4950 Pickup Group to the 6V2100 Multitach.

Specifications

Adaptability: or use on all non-unit injected Caterpillar diesel engines.

Engine Speed Range: 40 to 6000 rpm.

Pulses Per Revolution: Use .5 P/Rev (pulses per revolution) for all Caterpillar four stroke diesel engines.

Output Signal Amplitude: .75 volts peak minimum.

Noise: Less than .4 volts peak.

Operating Temperature Range: -23°C to +70°C (-9°F to 158°F).

Storage Temperature Range: -40°C to +100°C (-40°F to 212°F).

Size: Amplifier - 78 x 35 x 29 mm (3.1 x 1.4 x 1.1 in) plus 152 mm (6 in) output lead.

Pickup - 13 mm (.5 in) thick x 57 mm (2.25 in) diameter, plus a 915 mm (36 in) long output lead and a 305 mm (12 in) long ground lead.

Weight: Amplifier - 85 grams (3 oz).

Pickup - 56 grams (2 oz).

Operating Instructions

Important

To avoid personal injury and possible damage to the equipment, always observe the following warnings and notices when using the injection line speed pickup group.

Show/hide table

All bare metal locations on the fuel injection lines must be repainted after removal of the pickup group and before the engine is put back into service. If this is not done, the bare metal fuel injection lines can corrode. This could result in a fire if fuel is sprayed on hot engine parts.

Installation of the Pickup

1. Select a location for mounting the pickup on one of the engines fuel injection lines. Although the pickup will work on any straight section of fuel injection line, the location selected should have sufficient clearance to permit installation of the pickup without touching other parts of the engine.

This location on the injection line must have a minimum of 15 mm (.6 in) of clearance with adjacent injection lines and a minimum of 25 mm (1 in) clearance under the line as shown. Do not attempt to install the pickup on a curved section of the injection line.

2. Use a knife or emery paper to remove paint from the injection line at the pickup mounting location. Remove the paint completely from around the line in a band approximately 10 mm (.39 in) wide as shown. Be careful not to nick or otherwise damage the injection line.

Show/hide table

All bare metal locations on the fuel injection lines must be repainted after removal of the pickup group and before the engine is put back into service. If this is not done, the bare metal fuel injection lines can corrode. This could result in a fire if fuel is sprayed on hot engine parts.

(1) Thumbscrew. (2) Pickup. (3) Ground clip.

3. Loosen thumbscrew (1) on the pickup by turning it counterclockwise. Open pickup (2) and place it over the fuel injection line at the location where the paint has been removed. Close the pickup over the line and tighten the thumbscrew finger tight. Do not use any tools to tighten the thumbscrew.

4. After the pickup has been installed, check to be sure it is not touching any part of the engine except the injection line on which it is installed. Connect ground clip (3) on the pickup to bare metal on the engine.

(4) Pickup signal cable. (5) Amplifier. (6) Switch. (7) Output connector.

5. Connect pickup signal cable (4) to amplifier (5). Make sure switch (6) is in the INJ LINE position. Make sure signal cable (4) does not contact any hot parts of the engine; if necessary, fasten the cable temporarily in place. Make sure amplifier (5) does not contact the engine.

6. Connect output connector (7) of the amplifier to the PH (photo) input connector on the 6V2100 Multitach. If a longer cable is needed, use the 6V2198 Photo Pickup Extension Cable.

Using the Injection Line Speed Pickup Group

1. Refer to Special Instruction, SEHS7807, "Using the 6V2100 Multitach and 6V3121 Multitach Group", to become familiar with the operation of the multitach.

Connect the 5P7366 Power Cable to the multitach and to the power source as shown in the Special Instruction. Start the engine. Program the multitach for .5 P/REV, and to read R/MIN on the PH (photo) input.

2. Read engine speed on the digital display of the multitach.

If engine speed is steady, the multitach reading should be stable.

If the reading on the multitach is not stable, check the NO INPUT Signal light.

When the engine speed is steady, there should either be a steady dim light or the light should be flashing off and on at a constant rate. This rate will vary with engine speed. The rate will be easier to observe at lower engine speeds, when it will be slower.

If the NO INPUT SIGNAL light is on constant bright or is flashing erratically, the pickup is either faulty or incorrectly installed. Refer to the Troubleshooting Section for additional information.

3. If the engine speed readings have been successfully completed, remove the multitach, amplifier and the pickup from the engine.

Show/hide table

All bare metal locations on the fuel lines must be repainted after removal of the pickup group and before the engine is put back in service. If this is not done, the bare metal fuel injection lines can corrode. This could result in a fire if fuel is sprayed on hot engine parts.

4. After the engine has cooled, repaint the fuel injection line at all locations where the paint has been removed.

Troubleshooting Operational Problems

If the NO INPUT SIGNAL light is on constant bright or is flashing erratically when the engine is running at a steady speed, the following steps should be taken to solve the problem.

1. Make sure that the switch on the amplifier is in the INJ LINE position.

2. Remove the pickup from the injection line. Check to be sure the pickup and injection line are clean and dry. The inner bore of the pickup that contacts the injection line must also be clean and dry. If necessary, clean the inner bore with a soft cloth. If the pickup is damp, dry it in an oven at approximately 50°C (122°F) before reinstalling on the fuel injection line.

3. Check the fuel injection line on which the pickup was installed. Make sure that all paint has been removed from around the line and that clean bare metal is exposed. Use fine emery paper to clean the line if necessary.

4. Reinstall the pickup on the fuel injection line. Make sure the thumbscrew is tight and the pickup is not touching anything except the line.

Observe the NO INPUT SIGNAL light and the digital readout on the multitach. If the light stays on bright all the time and the digital display reads 0 when the engine is running, the pickup is not operating.

Remove the pickup and amplifier, and test the pickup and amplifier as described in the topic "Checking the Operation Of the Amplifier and Pickup", or use a different pickup and amplifier.

5. If the pickup is operating, but the NO INPUT SIGNAL light and digital readout are erratic, the pickup output signal is either too low or it is noisy. Run the engine at low and high speeds.

* If the output signal is too low, the pickup will operate better at high speeds.

* If the signal is noisy, the pickup will usually perform better at low speeds.

* To correct either of these problems, loosen the thumbscrew and rotate the pickup to a new position on the line. Tighten the thumbscrew. Check to see if this solves the problem.

* To correct noisy operation, it may also be necessary to remove the pickup and reverse it 180° so that the signal line points in the opposite direction.

6. If pickup operation is still erratic after performing the previous steps, move the pickup to a new location on the same line or to a different line.

* Make sure that each new location is properly prepared before installing the pickup.

* To correct noisy operation (erratic signal and high speed readings), try a pickup location as close as possible to a point where the injection line is fastened to the engine.

Use of the Pickup During Wet Conditions

If the pickup becomes wet, it may operate intermittently or not at all. Although the pickup is water resistant, it is not waterproof. Water spray from rain or other sources may cause the pickup to stop producing an output signal.

If this happens, the pickup should be removed from the engine and allowed to dry out thoroughly. If necessary, the pickup can be dried in an oven at approximately 50°C (122°F). After drying, the pickup should operate correctly.

If it is not possible to keep the pickup dry, use the following procedure:

If the pickup must be used during wet conditions, it may be possible to protect it from moisture by using a water displacing spray such as WD-40®.

Remove the pickup from the engine. Thoroughly spray the pickup from all directions. Make sure the pickup is completely covered with the spray. Reinstall the pickup on the engine and check its operation.

When water first contacts the pickup, the unit may stop working temporarily, but will start working again after the water has been displaced by the solution. If necessary, spray the solution on the pickup after installation on the injection line.

Permanent Installation on the Engine

If the pickup is to be permanently installed on the engine, install the pickup on the fuel injection line in the usual manner. Make sure that the thumbscrew is hand tightened securely, but not over tightened. Run the engine and check the operation of the pickup.

Make sure that the pickup and line are clean and dry. If the pickup is working correctly, use a can of spray paint to thoroughly paint the pickup from all directions. Several coats should be applied. Let the paint dry thoroughly before operating the engine.

Checking the Operation of the Amplifier and Pickup

(1) 6V2100 Multitach. (2) 5P9698 Calibrator. (3) 5P7366 Power Cable. (4) Digital Multimeter. (5) Screwdriver. (6) 6V6152 Adapter.

NOTE: Screwdriver (5) should have a blade approximately 150 mm (6 in) long with 6 mm (.25 in) diameter shaft of round bare metal (not anodized or insulated).

The 6V6152 Adapter (6) is a phono plug-to-BNC connector.

NOTE: Modifications must be made to the 5P9698 Calibrator (2). Refer to Special Instruction, SMHS7504-01.

Checking the 4C6812 Amplifier

(1) 6V6152 Adapter Plug. (2) 5P9698 Calibrator. (3) 4C6812 Amplifier. (4) Connector. (5) 5P7366 Power Cable. (6) Knob. (7) Battery Indicator. (8) No Input Signal Light.

1. Install 6V6152 Adapter Plug (1) on the end of the output cable on 5P9698 Calibrator (2). Plug the adapter into 4C6812 Amplifier (3).

2. Check the operation of the multitach being used by performing the CHECKING PHOTO OPERATION test procedure contained in Special Instruction SEHS7807. (This is to ensure it is operating correctly on PHOTO operation.)

3. Plug connector (4), on the end of the amplifier output cable, into the PH (photo) connector on the multitach. Attach 5P7366 Power Cable (5) to the multitach and to a suitable power source. Refer to SEHS7807.

4. Program the multitach for .5 P/REV and to read R/MIN on the PH (photo) input. Turn knob (6) on the calibrator to the 25 Output Hz position.

Make sure BATTERY indicator needle (7) is in the white part of the scale. The NO INPUT SIGNAL light (8) on the multitach should go off or become dim, and the number 3000 (± 1) should appear on the digital readout. If this number is correct, the amplifier is working properly.

NOTE: The 25 Output Hz position is the only calibrator position that can be used for this test. Test results should be the same with the amplifier switch in either the INJ LINE or MAG positions. Conduct the test with the switch in both positions to fully test the amplifier circuitry.

5. Leave the test equipment connected to the amplifier, and check the pickup as shown in the following procedure.

Checking the 1U9139 Pickup

1. Make sure that the pickup is clean and dry. Perform the preceding test procedure "Checking the 4C6812 Amplifier".

(1) 5P9698 Calibrator. (2) 6V6152 Adapter Plug. (3) 4C6812 Amplifier.

(3) Amplifier. (4) Switch. (5) Cable.

2. Remove 5P9698 Calibrator (1) and 6V6152 Adapter Plug (2) from 4C6812 Amplifier (3). Make sure that switch (4) is in the INJ LINE position. Connect cable (5) of the pickup to amplifier (3). Leave the multitach programmed to read R/MIN as described in the amplifier test procedure.

3. Install the pickup on the shaft of the 150 mm (6 in) screwdriver as shown. Do not use a screwdriver with an anodized or insulated shaft.

The pickup should be positioned approximately 13 mm (.5 in) from the handle. Connect the ground clip to the screwdriver shaft next to (but not touching) the pickup.

4. Hold the screwdriver with the pickup by the handle (be careful not to touch the shaft). Hold another screwdriver by the shaft in your other hand. Rapidly strike the shaft of the screwdriver with the pickup with the handle of the other screwdriver as shown. Be careful not to hit the pickup or the clamp.

5. Observe the NO INPUT SIGNAL light on the multitach. The light should go out whenever the shaft is struck with the screwdriver handle.

After the shaft has been struck steadily for a minimum of five seconds, a number in the range of 200 to 800 should appear on the digital readout of the multitach. The number will vary with the rate the screwdriver is struck. If this number appears, the pickup is operating correctly. However, the pickup should also be checked on an engine to verify proper operation.

6. If the pickup does not operate, an additional test can be performed using a Digital Multimeter to check for a short circuit. Remove the pickup connector from the amplifier.

Use the multimeter on the 20 M Ohms (20 Meg ohms) scale to measure the resistance between the outer shell and the center conductor of the connector as shown. The multimeter should read OL (infinite ohms) on the readout. If the readout indicates a smaller (finite) resistance, the pickup is faulty or contaminated, or there is a short in the signal cable.

Repair of the 4C6821 Pickup Group

If the 4C6821 Injection Line Speed Pickup Group fails to operate correctly, check the performance of the amplifier and pickup as shown in this Special Instruction. If either unit is found to be faulty, it can be returned to Caterpillar Service Technology Group (CSTG).

Diagnostic Tool Repair Program Policies and Procedures

Repair Charge For:

1. Warranty repairs (One year from purchase date) - no charge.

2. Normal repairs - existing flat rate. Please contact CSTG for current flat rate prices.

3. Repairable components with major damage (major damage means replacement is needed for a major component such as a transducer, power cord, or pc board) - flat rate does not apply; CSTG will contact owner with a separate repair quote.

4. Additional components (something which is not included in the standard tool group) - advise owner if extra charges will exceed $25.00 U.S..

5. Non repairable tools - CSTG will advise owner of conditions and options, which are:

a. CSTG can replace with a new tool.

b. Owner can obtain replacement.

Freight/Shipping Policy

1. Owner pays shipping to CSTG (Peoria, II.), CSTG pays return shipping. This policy applies worldwide.

2. If you send tools not listed on the "Diagnostic Tools Repaired By CSTG" sheet, you will be invoiced for the costs to return or reship the tools.

Instructions

Documentation required when sending tool to CSTG.

1. Sender's name and phone number.

2. Part number and name of each tool.

3. Brief description of problem.

4. Return shipping address of owner.

5. Billing address of owner.

6. Purchase order number if required on invoice.

7. Owners outside the U.S. must specify what wording on customs declarations is required for CSTG to properly return tool.

CSTG shipping address

Inquiries

By Phone:

Outside Illinois 800 542-8665

Inside Illinois 800 541-8665

Electronics Lab (309) 675-6226

Facsimile: (309) 675-6618

Telex No.: 404435

Mail: