Cummins/Onan — Time the injection pump by depth micrometer
Adjustments
From a Cummins/Onan service manual covering: 205D3A, 3DJA, 3DJA-1E2236, 3DJA-3E2236. Check it applies to your exact model before use.
Applies to: Cummins/Onan DJA engine
Before you start
- Injection pump must be timed on the compression stroke, not exhaust stroke.
Procedure
- Install pump tappet in its recess.
- Position flywheel on port closing mark (PC) of compression stroke.
- Measure distance from pump mounting pad to tappet center with depth micrometer.
- Subtract measured depth from 1.670 in. port closing dimension.
- Result is thickness of shims necessary.
- Select correct shims and install pump.
Tools required
- Depth micrometer Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 1.670 in. port closing dimension
- Shims .006 in. to .052 in.
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.