Cummins/Onan — BIMETAL AND

A Cummins/Onan service procedure — check it applies to your exact model before use.

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Procedure

1. Lead tagged G goes to ground terminal on coil solenoid.
2. Lead tagged H goes to either H' terminal on solenoid core. FUEL PUMP A diaphragm-type fuel pump is used. If fuel does not teach the carburetor, check the fuel pump beforée dismantling it. The pump can be checked by disconnecting the fuel line at the carburetor, cranking the engine slowly by hand, and observing whether fuel comes from the fine at the carburetor. If there is enough fuel in the tank, and the line between the tank and the pump is open but the pump fails, repair or replace it. Fai
3. Make an indicating mark with a file across a point at the union of the fuel pump bolt and cover. This mark will assure proper reassembly. Remove assembly screws and remove upper pump body.
4. Turn pump body over and remove vaive plate screw and washer. Remove valve retainer, valves, valve springs and valve gasket, noting their posi- tion. Discard valve springs, valves and valve retainer gasket.
5. Clean pump body thoroughly with solvent and a fine wire brush.
6. Holding the pump cover with the diaphragm surface up, place the new valve gasket into the cavity. Assemble the valve spring and valves in the cavity. Reassembie the vaive retainer. Lock in position by inserting and tightening fuel pump vaive retainer screw.
7. Place pump body assembly in a clean place and rebuild the lower diaphragm section. . Holding mounting bracket, press down on the diaphragm to compress spring under it, then turn bracket 90 degrees to unhook diaphragm so itcan be removed.
8. Clean mounting bracket with a solvent and a fine wire brush. Pend
9. Replace the diaphragm fuel pump rod spring, diaphragm gasket, stand new spring in casting, position diaphragm, compress spring and turn $0 degrees to reconnect diaphragm.
10. Hold bracket, then place the pump cover on it (make sure that indicating marks are in line) and insert the four screws. DO NOT TIGHTEN. With the hand on the mounting bracket only, push the pump lever to the limit of its travel and hold in this position while tightening the four screws. This is important to prevent stretching the diaphragm. tt. Mount the fuef pump on engine, using new mounting gaskets. Connect the fuel lines. UPPER PUMP BODY (NOT SERVICEASLE) *VALVE GASKET—€>. *VALVE AND cage
11. Remove vacuum and fuel lines. inspect lines for wear, cracking, etc. PUMP COVER GASKET VALVE
12. Scribe two lines (one each on opposite ends of Pump) across pump parts. This will ensure cor- rect alignment of pump parts with each other and carburetor when pump is reassembled.
13. Remove fuel pump attaching screws.
14. Holding pump, carefully pull sections of the pump apart. The diaphragm, plunger, return spring and plate, pump body and gaskets will now be loose.
15. Check parts for wear and damage. Replace with new parts where necessary.
16. The air bleed hole in pump base must be unclogg- ed to allow unrestricted movement of diaphragm. A clogged diaphragm air bleed hole can cause diaphragm wear and seal damage while inhibiting pump operation.
17. Replace gaskets and reassemble pump as shown in Figure.
18. install pump and replace lines. Make sure fuei line clamps are replaced on fuel line. wannine } Use care when reassembling and reinstalling the pump. Improper partsalignment ot misconnected fuel lines may result in leaking tuel, creating a serious fire hazard. DIAPHRAGM PUMP PLATE SPRING PULSATING DIAPHRAGM FUEL PUMP 28 SISSON CHOKE This choke should not require any seasonal readjust- ment. If adjustment becomes necessary, pull choke lever up and insert a 1/16-inch (1.59 mm) diameter rod
19. Use a manometer which reads up to 14 inches (355.6 mm) water column. One ounce per square inch equals 1.73 inches (43.94 mm) water column. Likewise, one inch water column equals 0.58 Ounce per square inch.
20. Shut off gas supply. Temporarily remove the 1/8- inch pipe plug at regulator iniet for testing pressure.
21. Connect manometer to read gas supply line pressure.
22. Open gas supply line valve. Without delay, alter- nately cover and uncover the regulator outlet with the paim of your hand. At the same time watch the manometer. If the reguiator closes completely, as desired, the manometer will hold a steady reading.
23. Ifthe manometer reading drops slightly each time you remove your hand, the requlator is leaking. Turn the adjusting screw inward just far enough So that the manometer reading remains constant when you repeatedly cover and uncover the regulator outiet with your hand.
24. Close the gas supply line valve. Remove manometer. Bleed air from gas supply line. Install test-hole plug in regulator. Open gas supply line valve. . ?. See that vent fitting is instalied in the reguiator hole.
25. With a clamp on each end, secure the hose between the regulator outlet nipple and the carburetor inlet.
26. Operate the engine to assure quick starting results. LPG VAPORIZER The vaporizer-regulator consists of a high pressure regulator and a vaporizer in a single unit (Figure 24). Regulator portion of the vaporizer-regulator reduces LPG tank pressure to a uniform outlet pressure of 7 psi (48.3 kPa). The vaporizer section installed in the path of the engine cooling air system furnishes the heat required to offset the cooling effect produced as the LPG fuel is expanded and becomes gas. The vaporizer
27. Place the vaporizer in a vise or other suitable clamp. Attach an air hose from an air supply of approximately 75 psi (517.5 kPa) to the inlet, Figure 25,
28. Attach a pressure gauge capable of reading over7 psi (48.3 kPa) to the outlet.
29. Back off the adjusting screw until only one ortwo threads are engaged. Apply air pressure to the unit, PRESSURE AQVUSTING SCREW INLET PORT / 8167 4, Turnthe pressure adjusting screwin slowly until a reading of 7 psi shows on the gauge. To obtain an accurate gauge reading, it may be necessary to unscrew the gauge partially to bleed off some of the air. Then refighten the gauge and readjust for 7 psi (48.3 kPa). If the pressure reading remains steady, the valveis notleaking. ifthe pressure re
30. Tighten the lock nut on the pressure adjusting screw. Turn off the air pressure and remove the gauge and air line. PRESSURE ADIUSTING FIGURE 25. VAPORIZER ADJUSTMENT LIQUID PARTIALLY VAPORIZED DRY GAS FIGURE 24. LPG VAPORIZER 31 lat i! FUELOCK VENT Eo & FILTER H ope PROPANE f TANK GAS LINE FILTER PUBLOCK | | | | | MAIN POWER MIXTURE REGULATOR rh INTAKE VACUUNL LINE sOLE SCREW MANIFOLD. y ame ENGINE FIGURE 26. VAPOR WITHDRAWAL FUEL SYSTEM, BLOCK DIAGRAM LPG VAPOR WITHDRAWAL SY
31. Set main power mixture to position shown in Figure 31.
32. Turn idle screw in fully clockwise.
33. Turn idle screw out 2-1/2 to 3-1/2 turns coun- terclockwise,
34. Connect or turn on fuel supply to regulator.
35. Check (smell) for propane leaks.
36. Start engine—it should start within 20 seconds if fuel is available to carburetor. HO — al a” 2 FIGURE 31. INITIAL START ADJUSTMENT CHECKING FOR FUEL AT CARBURETOR { WARNING ) Do not permit any Hame, cigarette, or other igniter near the tuelsystem. Propane gas is highly flammable and potentially explosive in contlined spaces.
37. Disconnect fuel line at carburetor.
38. Momentarily, press primer button; you should smeil gas at end of fuel line. |fnot, check fuel lines back to supply tank. With experience, you should be able to feel gas pressure on the regulator diaphragm when you press the primer button.
39. Look for one or more shutoff devices.
40. On vacuum operated shutoff valve systems, close throttle (fully) to aid engine starting with better vacuum. 5 if fuel is present at carburetor, check ignition system or other engine malfunctions. CARBURETOR ADJUSTMENTS WITHOUT EXHAUST ANALYZER
41. Run new engine at least ten hours at normal service load. Avoid high loads before proper adjustments are made.
42. Run engine at maximum throttle and normal toad for ten minutes, or set main power mixture near mark between L and R as shown in Figure 31.
43. Set main power mixture as lean as possible without noticeable loss in power output. If frost develops and remains on regulator for more than five minutes, check for propane leaks and ensure that vaporizer coil wraps tightly around exhaust pipe. 4, Ifengine functions properly but frost remains on requiator, the carburetor power mixture is too tich. Adjust for maximum efficiency.
44. Recheck head bolt torque and valve lash after carburetor is adjusted. IDLE SCREW AND IDLE STOP
45. Run engine at idle speed (1200 rpm) for ten 35 minutes. 2, Adjust idle screw for maximum speed; maximum speed should be attained when idle screw is turned fully clockwise into carburetor.
46. Set idle stop screw speed at 1350 rpm.
47. Turn idle screw out until engine speed slows to 4200 rpm. CARBURETOR ADJUSTMENTS WITH EX~ HAUST ANALYZER Exhaust analyzers (with at least +3 percent accuracy) should be infra-red equipment, but flame ionization can be used for measur- ing hydrocarbon emissions which are n-hexane equivalent. Alldata is based on dry measurements which are obtained after removing all water vapor from the exhaust samples

Source: manual:927-0754 Onan CCK-CCKA-CCKB (Spec A-J) Engine Service Manual (03-1986)L.pdf. Figures and steps are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.