To determine if the fuel pump is causing starting difficulty, perform the following steps:
1. Insert a piece of wire through the pump flange drain hole, see Figure 4-3.
2. Crank the engine momentarily and feel for wire vibration.
[a] If the wire did not vibrate, determine if the drive hub or coupling should be replaced;
refer to section 4.9.1.
[b] If the wire did vibrate, check for aerated fuel. Refer to section 4.10.
Drive Hubs and Coupling Replacement
Perform the following steps for drive hub or coupling replacement:
1. Replace the drive hub or coupling; refer to the appropriate service manual, fuel system chapter.
2. Test the engine to determine if starting has been improved; refer to section 18.104.22.168.
Engine Test with Replaced Drive Hubs or Replaced Coupling
To determine if replaced drive hubs or coupling resolved starting difficulty, attempt to start and run the engine.
1. If the engine starts and runs, no further troubleshooting is required. Shut down the engine.
2. If the engine fails to start and run, check for aerated fuel; refer to section 4.10.