Cummins/Onan QST30 / QST30 G-Drive — Fuel Pump Installation (Flange Drive)
Repair & overhaul · Injection Pump
For the Cummins/Onan QST30 / QST30 G-Drive, from the Cummins/Onan service manual.
Applies to: Cummins/Onan QST30, Cummins/Onan QST30 engine
Before you start
- If the pump does not align, do NOT force the pump and driveshaft into alignment. Forcing will result in fuel pump damage.
- Severe damage to the fuel pump WILL occur unless the fuel pump is unlocked prior to operation.
Procedure
- Rotate the engine slowly clockwise to align the timing mark on the crankshaft damper with the timing pointer; ensure #1 cylinder (right bank) is on the compression stroke.
- Remove the timing pin cap and verify that the pump is locked.
- Install the timing pin (1), cap (2) and sealing washer (3); torque to 30 N-m [22 ft-lb].
- Install the spline coupling (1) onto the pump driveshaft gear.
- Engage the spline coupling and install the pump driveshaft gear into the drive housing.
- If the pump does not align, do NOT force it; align with the front and bottom pump support brackets.
- Install the four capscrews (1), washers and nuts that mount the pump to the drive housing; torque 66 N-m [49 ft-lb].
- Install the two front injection pump bracket mounting capscrews (1).
- Install the two bottom injection pump bracket mounting capscrews (2); torque 66 N-m [49 ft-lb].
- Install the low pressure fuel lines (2); torque 24 N-m [17 ft-lb]. Install the electrical connection (1). Install the high pressure fuel line (2); torque 24 N-m [17 ft-lb]. Install the fuel pump drain
- Tighten the three visible capscrews in the fuel pump drive gear; torque 115 N-m [84 ft-lb].
- Unlock the fuel pump timing.
- Rotate the engine one full revolution; tighten the fourth capscrew to 115 N-m [84 ft-lb].
- Re-install the cover plate on the front gear cover; torque 65 N-m [48 ft-lb].
Tools required
- Standard 3 jaw puller kit
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Timing Pin Cap 30 N-m [22 ft-lb]
- Pump to drive housing capscrews 66 N-m [49 ft-lb]
- Bracket mounting capscrews 66 N-m [49 ft-lb]
- Low/high pressure fuel lines 24 N-m [17 ft-lb]
- Drain line 9 N-m [80 in-lb]
- Drive gear capscrews 115 N-m [84 ft-lb]
- Cover plate 65 N-m [48 ft-lb]
Full service-parts list: Cummins/Onan QST30 →
Source: Cummins/Onan 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.