SCG Classic Car Troubleshooting Checklist - Carburetor Problems

Excessive Fuel Consumption

• Float level is too high or float is leaking internally
• Float valve is worn or dirty and won't seat properly
• Metering rods worn or jet openings worn
• Power jet not shutting off
• Idle mixture adjustments too rich
• Throttle shaft worn and leaking vacuum
• Accelerator pump stroke too long
• Choke stuck partially closed
• Fuel pump pressure too high
• Air cleaner dirty and clogged

Surging (Lean Mixture)

• Air leak in manifold or under carburetor
• Float bowl atmospheric vent clogged
• Float level too low
• Air bleeds clogged
• Incorrect main jet or metering rod
• Clogged jets
• Throttle shaft worn
• Fuel pump pressure too low
• Heat riser manifold leaking
• Vacuum leak

Poor Acceleration

• Accelerator pump faulty or linkage settings wrong
• Leaking check valve in pump circuit
• Float level too low
• Jets running too lean
• Vacuum leaks
• Throttle not opening fully (linkage)
• Choke valve stuck partially closed

Poor Idle

• Air leaking into manifold
• Mixture screws incorrectly adjusted or malformed at tips
• Float level too high
• Throttle shaft worn
• Dirty internal carburetor components (high mileage)
• Choke fast-idle linkage incorrectly adjusted

Stalling

• Dashpot improperly adjusted
• Air bleeds clogged
• Idle passages clogged (if screws have no effect, passages are clogged)
• Vacuum leak
• Idle speed too low