Series 50 – Section 16.1 Poor Vehicle Ground

Section 16.1
Poor Vehicle Ground

To determine if poor vehicle ground is causing the cylinder to misfire, perform the following steps:‪

1. Remove alternator belt.
2. Start the engine.
3. Run the engine through operating range.
4. Listen for engine misfiring.
   1. If the engine is still misfiring; refer to "16.1.1 Negative Lead Repair" .
   2. If the engine is not misfiring, check for aerated fuel; refer to "16.2 Aerated Fuel" . Shut the engine down.

Section 16.1.1
Negative Lead Repair

Perform the following steps for negative lead repair:‪

1. Shut down the engine.
2. Remove negative lead(s) at frame ground stud near battery box.
3. Clean ground stud; refer to OEM guidelines.
4. Clean negative lead(s) terminal lugs with low grit sandpaper.
5. Repair any loose or damaged lead(s), using the splice method or rosin core solder; refer to "30.1 Lead Repair" .
6. Install negative lead(s) to frame ground stud; refer to OEM guidelines.
7. Install alternator belt. Torque belt to:
   1. If installing a new belt, torque to 170 N·m (25 lb·ft).
   2. If installing a used belt, torque to 135 N·m (100 lb·ft).
   3. If a belt tension gage is not available, adjust the belt tension so that a firm push with the thumb, at a point midway between the two pulleys, will depress the belt 12.70-19.05 mm (0.500-0.750 in.).

   Note: When installing or adjusting an accessory drive belt, be sure the bolt at the accessory adjusting pivot point is properly tightened, as well as the bolt in the adjusting slot.

   Note: Drive belts (V and Poly-V) should be replaced every 2,000 hours or 100,000 miles (160,000 km).

8. Verify negative lead repair; refer to "16.1.1.1 Verification of Repair for Negative Lead" .

Section 16.1.1.1
Verification of Repair for Negative Lead

Perform the following steps to determine if negative lead repair resolved the misfiring cylinder condition: ‪

1. Start engine.
2. Run engine speed up to the occurrence of the misfiring.
3. Listen for misfiring cylinder.
   1. If the engine is not misfiring, no further troubleshooting is required. Shut down the engine.
   2. If the engine is misfiring, check for aerated fuel. Shut down the engine; refer to "16.2 Aerated Fuel" .