Usage:
Introduction
Maintaining the accuracy of fuel system test equipment (fuel pump test stands and nozzle/injector pop testers) should be a high priority in each fuel system service shop to assure high quality repairs and satisfied customers.
This procedure provides information on how to select, test and chart reference parts (using available fuel system parts in a dealer's shop) for checking and maintaining accuracy of fuel systems test equipment.
Creating reference parts is recommended in addition to preventative maintenance recommendations discussed in Caterpillar Special Instructions.
Creating a reference part will allow each fuel system technician to check their test stand or pop tester as a complete unit.
Reference parts should be selected from used fuel system components that are available and in good working order. Selected reference parts must be identified so it will not mistakenly be installed in an engine.
Fuel Pump Reference Parts
1. Select a pump typically serviced in your dealer shop.
NOTE: Do NOT use electronic (PEEC) fuel pumps as reference parts. A 3306B pump is recommended for your reference pump.
2. If necessary, disassemble and visually inspect pump cam, lifters, plunger and barrel, etc. to assure all internal components are in good condition.
3. Check pump plunger and barrel bonnet nut torque. Torque nuts to recommended value according to the service manual.
4. Back out the pump governor load stop(s) and idle setting screws.
5. Obtain the required pump rack zero pin. It is recommended each reference pump have its own zero pin (order a spare from the parts department) and permanently attach to the reference pump.
6. Install the reference pump on the test stand.
7. Make sure the test stand has the latest master fuel nozzles. All master nozzles must have the same part number.
8. Inspect each test stand high pressure fuel line inside diameter (ID) for "close-in" from repeated use.
Repeated assembly of the high pressure fuel lines can cause the tubing's inside diameter to collapse or "close-in", resulting in low delivery volume. Testing fuel injection pumps using worn or partially closed high pressure fuel lines will cause inaccurate test results. All high pressure fuel lines used on the test stand should be checked every three months.
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Always use a wrench to hold the hex fitting on top of the master nozzle, when assembling or disassembling lines. If a wrench is not used, the master nozzle and manifold it is installed into may be damaged. |
Check fuel line for "Close-in"
NOTE: Do NOT use fuel lines with an ID (inside diameter) LESS than 1.191 mm (0.0469 in). The fuel line ID can be checked using a 1.2 mm (.047 in) drill.
If the drill bit can NOT be inserted into the fuel line high pressure hole, either drill out the line using a 1.6 mm (.063 in) drill or replace the fuel line with a new line. Use the same length and internal diameter lines each time the reference pump is tested.
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If the fuel lines are not completely and thoroughly cleaned out after the drilling procedure, metal particles or foreign debris in the line will damage the master nozzles and contaminate the calibration fluid in the test stand. |
After the hole has been drilled to the correct size, clean the line with solvent and remove any metal particles. Blow compressed air through the lines, after cleaning, to remove any solvent.
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When using pressure air, wear a protective face shield and protective clothing. The maximum air pressure at the nozzle must be less than 205 kPa (30 psi) for cleaning purposes. |
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9. Identify fuel lines and nozzles in the same order as the reference pump plunger and barrels (1-6 or 1-12) and use the same lines and nozzles each time the reference pump is run on the test bench.
10. Select two test points (speeds and shot settings) that will cover the delivery range realized in a dealer's shop.
Always set up the test points using only the pump rack zero pin. Do not set the rack full load or idle stops.
11. The test stand and reference pump should be run for ten minutes.
Make sure test stand pressures and temperatures are within published specifications and that they are stable.
12. Set the first test point.
Take five samples (draws) and record the individual pump and barrel deliveries for each sample (draw).
13. Examine pump and barrel sample data:
* Are the samples consistent?
The MAXIMUM allowable difference between the HIGH and LOW delivery pump and barrel in the reference pump should be three cc's.
If there is NOT a three cc difference, swap pump and barrels in the pump housing (or check master nozzles for damage) and re-test UNTIL the maximum HIGH to LOW difference is three cc's.
If necessary, replace used pump and barrels (or master nozzles) with new parts.
14. Set the second test point (speed and shot settings), make sure test stand pressures and temperatures are stable; take another five samples.
15. Examine pump and barrel sample data:
* Are they consistent?
The MAXIMUM allowable difference between the HIGH and LOW delivery pump and barrel in the reference pump should be three cc's.
If there is NOT a three cc difference, swap pump and barrels in the pump housing (or check master nozzles for damage) and re-test until the maximum HIGH to LOW difference is three cc's.
If necessary, replace used pump and barrels (or master nozzles) with new parts.
Illustration 1. Example control chart, [Statistical Process Control (S.P.C.)].
Illustration 2. Example control chart, [Statistical Process Control (S.P.C.)].
16. Create a control chart for each speed and shot setting.
Using the five sample data from each speed and shot setting:
- * Calculate the average delivery for each pump and barrel
- * ADD all individual pump and barrel deliveries ... and
- * DIVIDE by the number of pump and barrels to chart the average number.
- * ADD all individual pump and barrel deliveries ... and
17. Subtract the lowest from the highest pump and barrel reading and record in the RANGES portion of the chart (see Illustration 1 and 2). Blank S.P.C control charts are available through Caterpillar Corporate Literature, Form Number; 01-889-036679-01.
18. Dependent upon how often the pump test stand is operated, establish a schedule (every two weeks, once a month, etc) to operate the reference pump (lines, nozzles, speeds, shot settings) by the same procedure as shown.
19. Keep the control charts up to date, use the information as a reference to indicate a problem with the test stand.
Reference Pump Identification, Protection and Storage
Pump Identification
Identify the pump with paint, permanent tag, or engrave: "REFERENCE PUMP - FOR BENCH TEST ONLY".
Protection
Use plastic or metal protective caps to plug all pump and barrel, oil and fuel supply/return ports.
Storage
Coat the pump with calibration fluid, wrap it in plastic, and store in a clean and dry place.
Fuel Nozzle Reference Parts
1. Select one or two used 3200, 3300 or 3400 Caterpillar 7000 series fuel nozzles that have been tested in the shop.
NOTE: Do NOT use fuel nozzles that may have been overheated in an engine.
2. Check the fuel nozzle adapter nut torque; make sure the nut is not loose.
3. Check the fuel nozzle pop tester to assure it is in the proper working order (refer to the Special Instruction for Nozzle Pop Tester).
4. Check the pop tester calibration fluid. Replace the fluid and filter if dirty, diluted or contaminated with diesel fuel.
5. Select one fuel system technician to perform the testing (this minimizes test result variation due to operator method).
6. Run five tests of each feature, valve opening pressure (VOP), Tip Leak and Seal Leakage, for each reference part.
Record the values collected from each test.
Use the Seal Leakage Test to check the overall condition of the pop tester for any leaks.
Record and chart the pressure loss after 15 seconds for future use in assuring the pop tester does NOT have internal leaks or leaks in pipe connections.
7. Make a simple control chart for each feature tested.
Using the five test data from each feature:
- * Calculate the average value by ADDING all five tests together and DIVIDING the TOTAL by 5.
- * Chart the average number.
8. SUBTRACT the LOWEST value from the HIGHEST value (of the five tests for each feature), and record in the RANGE portion of the chart.
9. Depending on how often the injector pop tester is used, set up a schedule (every two weeks, once a month, etc) to test your reference injector(s) by the same procedure as shown above.
10. Keep the control charts up to date and use the charts as a reference to indicate a problem with the pop tester.
Reference Nozzle Identification, Protection and Storage
Identification
Identify reference nozzle(s) with paint, permanent tag or engrave "REFERENCE NOZZLE - POP TESTER USE ONLY" on the outside of the nozzle(s).
Protection
Place protective caps on reference nozzle(s), soak in calibration fluid.
Storage
Wrap in plastic and store in a clean and dry place.