Cummins/Onan — GARRETSON REGULATOR

For these Cummins/Onan models: 6JB, 7.5JB, J-Series (2-cylinder), J-Series (4-cylinder), JC.

Applies to: Cummins Onan 6Jb, Cummins Onan 7 5Jb

Procedure

1. Check the fuel tank and see that the shut-off valve is open.
2. Remove the fuel line from the pump outlet and crank the engine over several times. On manual models, operate the priming lever instead of cranking the engine. Fuel should ‘spurt out of the pump. If not, remove the pump for repair or replacement. Testing: If the fuel pump delivers fuel, test it with a pres- sure gauge or manometer. Perform these tests before remov- ing the pump from the engine. Disconnect the pump outlet line and install the pressure gauge (Fig. 7). Test the valves and diaphrag
3. Remove the pump inlet and outlet. Remove the two cap~ screws holding the pump to the engine and lift it off.
4. Notch the pump cover and body with a file for assembly in the same relative position, and remove the six screws holding them together.
5. Tap the body with a screwdriver to separate the two parts. Don’t pry them apart — this may damage the diaphragm.
6. Lift out the diaphragm assembly and diaphragm spring. Repair: Fuel pump failure is usually due to a leaking dia- phragm, valve or valve gasket. A kit is available for replace- ment of ‘these parts. Because the extent of wear cannot easily be detected, replace all parts in the kit. If the die phragm is broken or leaks, check for diluted crankcase oil. TO MANUAL CHOKE CONTROL KNOB ON OUTSIDE OF BLOWER HOUSING. FIGURE 9. MANUAL CHOKE Occasionally, failure is due to a broken or weak spring or we

Source: manual:967-0500 Onan JB JC (spec A-T) Genset Service manual MAGNECITER END (11-1971).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.