ENGINE PERFORMANCE
CARBURETOR TROUBLESHOOTING:
| NOTE: | This is GENERAL information. This article is not intended to be specific to any unique situation or individual vehicle configuration. The purpose of this Troubleshooting information is to provide a list of common causes to problem symptoms. For model-specific Troubleshooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing. |
BASIC COLD START SYMPTOMS TROUBLESHOOTING CHART
| CONDITION & POSSIBLE CAUSE | CORRECTION | |
|---|---|---|
| Engine Won't Start | ||
| Choke not closing | Check choke operation, see FUEL SYSTEMS | |
| Choke linkage bent | Check linkage, see FUEL SYSTEM | |
| Engine Starts, Then Dies | ||
| Choke vacuum kick setting too wide | Check setting and adjust see, FUEL SYSTEMS | |
| Fast idle RPM too low | Reset RPM to specification, see TUNE-UP | |
| Fast idle cam index incorrect | Reset fast idle cam index, see FUEL SYSTEMS | |
| Vacuum leak | Inspect vacuum system for leaks | |
| Low fuel pump outlet | Repair or replace pump, see FUEL SYSTEMS | |
| Low carburetor fuel level | Check float setting see FUEL SYSTEM | |
| Engine Quits Under Load | ||
| Choke vacuum kick setting incorrect | Reset vacuum kick setting,see FUEL SYSTEMS | |
| Fast idle cam index incorrect | Reset fast idle cam index, see FUEL SYSTEM | |
| Incorrect hot fast idle speed RPM | Reset fast idle RPM, see TUNE-UP | |
| Engine Starts, Runs Up, Then Idles, Slowly With Black Smoke | ||
| Choke vacuum kick set too narrow | Reset vacuum kick, see FUEL SYSTEMS | |
| Fast idle cam index incorrect | Reset fast idle cam index, see FUEL SYSTEMS | |
| Hot fast idle RPM too low | Reset fast idle RPM, see TUNE-UP | |
BASIC HOT START SYMPTOMS TROUBLESHOOTING CHART
| CONDITION & POSSIBLE CAUSE | CORRECTION | |
|---|---|---|
| Engine Won't Start | ||
| Engine flooded | Allow fuel to evaporate | |
BASIC COLD ENGINE DRIVEABILITY SYMPTOMS TROUBLESHOOTING CHART
| CONDITION & POSSIBLE CAUSE | CORRECTION | |
|---|---|---|
| Engine Stalls in Gear | ||
| Choke vacuum kick setting incorrect | Reset choke vacuum kick, see FUEL SYSTEMS | |
| Fast idle RPM incorrect | Reset fast idle RPM, see TUNE-UP | |
| Fast idle cam index incorrect | Reset fast idle cam see FUEL SYSTEMS | |
| Acceleration Sag or Stall | ||
| Defective choke control switch | Replace choke control switch | |
| Choke vacuum kick setting incorrect | Reset choke vacuum kick see, FUEL SYSTEMS | |
| Float level incorrect (too low) | Adjust float level, FUEL SYSTEMS | |
| Accelerator pump defective | Repair or replace pump see FUEL SYSTEMS | |
| Secondary throttles not closed | Inspect lockout adjustment, see FUEL SYSTEMS | |
| Sag or Stall After Warmup | ||
| Defective choke control switch | Replace choke control switch, see FUEL SYSTEMS | |
| Defective accelerator pump | Replace pump, see FUEL SYSTEMS | |
| Float level incorrect (too low) | Adjust float level, see FUEL SYSTEMS | |
| Backfiring & Black Smoke | ||
| Plugged heat crossover system | Remove restriction | |
BASIC WARM ENGINE DRIVEABILITY SYMPTOMS TROUBLESHOOTING CHART
| CONDITION & POSSIBLE CAUSE | CORRECTION | |
|---|---|---|
| Hesitation With Small Amount of Gas Pedal Movement | ||
| Vacuum leak | Inspect vacuum lines | |
| Accelerator pump weak or inoperable | Replace pump, see FUEL SYSTEMS | |
| Float level setting too low | Reset float level, see,FUEL SYSTEMS | |
| Metering rods sticking or binding | Inspect and/or replace rods, see FUEL SYSTEMS | |
| Carburetor idle or transfer system plugged | Inspect system and remove restriction | |
| Frozen or binding heated air inlet | Inspect heated air door for binding | |
| Hesitation With Heavy Gas Pedal Movement | ||
| Defective accelerator pump | Replace pump, see FUEL SYSTEMS | |
| Metering rod carrier sticking or binding | Remove restriction | |
| Large vacuum leak | Inspect vacuum system and repair leak | |
| Float level setting too low | Reset float level, see FUEL SYSTEMS | |
| Defective fuel pump, lines or filter | Inspect pump, lines and filter | |
| Air door setting incorrect | Adjust air door setting, see FUEL | |
