Deutz — Air-venting the Fuel System
Maintenance
From a Deutz owner's manual covering: F 3L 912, F 4L 912, F 5L 912, F 6L 912, F3L F4L F5L F6L. Check it applies to your exact model before use.
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Procedure
- Ensure tank is never run dry.
- For in-line pump with Bosch lift pump: release hex. bolt of spill valve by two or three turns.
- Turn knurled knob of hand priming pump counter-clockwise to release, then pump up and down until fuel free from air bubbles emerges.
- Retighten hex. bolt and screw hand priming pump knob back to locked position.
- For Pierburg lift pump: operate priming lever downwards until fuel free of bubbles emerges at spill valve after removing hex. bolt; refit hex. bolt.
- For distributor-type pump: loosen vent plug on two-stage fuel filter until fuel comes out free from bubbles.
- Loosen vent plug on injection pump and operate starter motor until fuel comes out free from bubbles.
- If injection lines were taken down, air-vent them by operating starter motor until fuel free from bubbles emerges at union nut after slackening 2 or 3 turns; speed control must be on full speed.
Source: Deutz owner's 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.