B Charts

Chart B-1 Restricted Exhaust System Check:

ALL ENGINES
Proper diagnosis for a restricted exhaust system is essential before any components are replaced. Either of the following procedures may be used for diagnosis, depending upon engine or tool used:

CHECK AT AIR INJECTION REACTOR (A.I.R.) PIPE
1. Remove the rubber hose at the exhaust manifold A.I.R. pipe check valve. Remove check valve.

2. Connect a fuel pump pressure gauge to a hose and nipple from a Propane Enrichment Device (J26911).

3. Insert the nipple into the exhaust manifold A.I.R. pipe.

CHECK AT Oxygen (O2) SENSOR
1. Carefully remove O2 sensor.

2. Install Boroughs exhaust backpressure tester (BT 8515 or BT 8603) or equivalent in place of O2 sensor.

3. After completing test described below be sure to coat threads of O2 sensor with anti- seize compound prior to re-installation.

DIAGNOSIS
1. With the engine idling at normal operating temperature, observe the exhaust system backpressure reading on the gauge. Reading should not exceed 8.6 kPa (1.25 psi).

2. Increase engine speed to 2000 rpm and observe gauge. Reading should not exceed 20.7 kPa (3 psi).

3. If the backpressure at either speed exceeds specification, a restricted exhaust system is indicated.

4. Inspect the entire exhaust system for a collapsed pipe, heat distress, or possible internal muffler failure.

5. If there are no obvious reasons for the excessive backpressure, the catalytic converter is suspected to be restricted and should be replaced using current recommended procedures.