John Deere — Bleed the Fuel System

Maintenance

From a John Deere service manual covering: 4045, 4045TF120, 6068, 6068TF120, 6068TF250, T06068TF220, T06068TF250, T06068TFM50. Check it applies to your exact model before use.

Applies to: John Deere 4045, John Deere 4045TF120, John Deere 6068, John Deere 6068TF120, John Deere 6068TF250, John Deere POWERTECH 4.5 L & 6.8 L Diesel Engines (4045 / 6068) engine

Procedure

1. Loosen the air bleed vent screw two full turns by hand on fuel filter base.
2. Operate supply pump primer lever until fuel flow is free from air bubbles.
3. Tighten bleed plug securely; continue operating hand primer until pumping action is not felt.
4. Push hand primer inward (toward engine) as far as it will go.
5. Start engine and check for leaks.
6. Stanadyne rotary pumps: slightly loosen fuel return line connector at injection pump.
7. Operate primer lever until fuel without air bubbles flows from return line connection; tighten connector to 27 N•m (20 lb-ft).
8. Delphi/Lucas rotary pumps: loosen bleed screw on pump cover; operate primer lever or turn ignition ON until fuel flows free of bubbles; tighten bleed screw.
9. Denso/Motorpal in-line pumps: open fuel filter port plug; operate hand primer until bubble-free fuel flows; close plug while stroking primer down.
10. If needed, bleed at injection nozzles: move speed control lever to half throttle.
11. Using two open-end wrenches, loosen fuel line connection at injection nozzle.
12. Crank engine with starter motor (do not start) until bubble-free fuel flows out of loosened connection.
13. Tighten connection to 27 N•m (20 lb-ft); repeat for remaining nozzles.

Full service-parts list: John Deere 4045 →, John Deere 6068 →, John Deere 6068TF250 →

Source: John Deere service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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