Troubleshoot hard starting, rough idle, slow acceleration, Misfire, poor gas mileage, etc.

General Auto Repair

Hard Starting

• Binding carburetor linkage: Eliminate binding
• Binding choke linkage: Eliminate binding
• Binding choke piston: Eliminate binding
• Restricted choke vacuum: Check vacuum lines for blockage
• Worn or dirty needle valve and seat: Clean carburetor
• Float sticking: Readjust or replace float
• Incorrect choke adjustment: Reset choke adjustment
• Defective coil: Replace coil
• Improper spark plug gap: Regap spark plugs
• Incorrect ignition timing: Reset ignition timing

Detonation

• Over-advanced ignition timing: Reset ignition timing
• Defective spark plugs: Replace spark plugs
• Fuel lines clogged: Clean fuel lines
• EGR system malfunction: Check and repair EGR system
• PCV system malfunction: Repair PCV system
• Vacuum leaks: Check and repair vacuum system
• Loose fan belts: Tighten or replace fan belts
• Restricted airflow: Remove restriction
• Vacuum advance malfunction: Check distributor operation

Dieseling

• Binding carburetor linkage: Eliminate binding
• Binding throttle linkage: Eliminate blinding
• Binding choke linkage or fast idle cam: Eliminate binding
• Defective idle solenoid: Replace idle solenoid
• Improper base idle speed: Reset idle speed
• Incorrect ignition timing: Reset ignition timing
• Incorrect idle mixture setting: Reset idle mixture

Faulty Acceleration

• Incorrect ignition timing: Reset ignition timing
• Engine cold and choke too lean: Adjust choke and allow engine to warm-up
• Defective spark plugs: Replace spark plugs
• Defective coil: Replace coil

Faulty Low Speed Operation

• Clogged idle transfer slots: Clean idle transfer slots
• Restricted idle air bleeds and passages: Disassemble and clean carburetor
• Clogged air cleaner: Replace air filter
• Defective spark plugs: Replace spark plugs
• Defective ignition wires: Replace ignition wire
• Defective distributor cap: Replace distributor cap

Faulty High Speed Operation

• Incorrect ignition timing: Reset ignition timing
• Defective distributor centrifugal advance: Replace advance mechanism
• Defective distributor vacuum advance: Replace advance unit
• Incorrect spark plugs or plug gap: Check gap and/or replace spark plugs
• Faulty choke operation: Check choke and repair as required
• Clogged vacuum passages: Remove restrictions
• Improper size or clogged main jet: Check jet size and clean
• Restricted air cleaner: Check filter and replace as necessary
• Defective distributor cap, rotor or coil: Replace cap, rotor or coil

Misfire at All Speeds

• Defective spark plugs: Replace spark plugs
• Defective spark plug wires: Replace spark plug wires
• Defective distributor cap, rotor, or coil: Replace cap, rotor, or coil
• Cracked or broken vacuum hoses: Replace vacuum hoses
• Vacuum leaks: Repair vacuum leaks
• Fuel lines clogged: Remove restriction

Hesitation

• Cracked or broken vacuum: Replace vacuum hoses hoses
• Vacuum leaks: Repair Vacuum leaks
• Binding carburetor linkage: Eliminate binding
• Binding throttle linkage: Eliminate binding
• Binding choke linkage or fast idle cam: Eliminate binding
• Cracked or broken ignition wires: Replace ignition wires

Rough Idle, Missing or Stalling

• Incorrect curb idle or fast idle speed: Reset idle speed
• Incorrect basic timing: Reset ignition timing
• Improper idle mixture adjustment: Reset idle mixture
• Improper feedback system operation: Check feedback system
• Incorrect spark plug gap: Reset spark plug gap
• Moisture in ignition components: Dry components
• Loose or broken ignition wires: Replace ignition wires
• Damaged distributor cap or or rotor: Replace distributor cap or rotor
• Faulty ignition coil: Replace ignition coil
• Fuel filter clogged or worn: Replace fuel filter
• Damaged idle mixture screw: Replace idle mixture screw
• Improper fast idle cam adjustment: Reset fast idle cam adjustment
• Improper EGR valve operation: Replace EGR valve
• Faulty PCV valve air flow: Replace PCV valve
• Choke binding or improper choke setting: Reset choke or eliminate binding
• Vacuum leak: Repair vacuum leak
• Improper float bowl fuel level: Reset float adjustment
• Clogged air bleed or idle passages: Clean carburetor passages
• Clogged or worn air cleaner filter: Replace air filter
• Faulty choke vacuum diaphragm: Replace diaphragm
• Exhaust manifold heat valve inoperative: Replace heat valve
• Improper distributor spark advance: Check distributor operation
• Leaking valves or valve components: Check and repair valvetrain
• Improper carburetor mounting: Remove and remount carburetor
• Excessive play in distributor shaft: Replace distributor
• Loose or corroded wiring connections: Repair or replace as required

Engine Surges

• Improper PCV valve airflow: Replace PCV valve
• Vacuum leaks: Repair vacuum leaks
• Clogged air bleeds: Remove restriction
• EGR valve malfunction: Replace EGR valve
• Restricted air cleaner filter: Replace air filter
• Cracked or broken vacuum hoses: Replace vacuum hoses
• Cracked or broken ignition wires: Replace ignition wires
• Vacuum advance malfunction: Check unit and replace as necessary
• Defective or fouled spark plugs: Replace spark plugs
• Incorrect ignition timing: Reset ignition timing
• Distributor centrifugal or vacuum advance malfunction: Check operation and replace as necessary
• Carburetor setting too lean: Readjust mixture setting
• Vacuum leak: Eliminate vacuum leak
• EGR valve malfunction: Replace EGR valve

Poor Gasoline Mileage

• Cracked or broken vacuum: Replace vacuum hoses hoses
• Vacuum leaks: Repair vacuum leaks
• Defective ignition wires: Replace wires
• Incorrect choke setting: Readjust setting
• Defective vacuum advance: Replace vacuum advance
• Defective spark plugs: Replace spark plugs
• Binding carburetor power piston: Eliminate binding
• Dirt in carburetor jets: Clean and/or replace jets
• Incorrect float adjustment: Readjust float setting
• Defective power valve: Replace power valve
• Incorrect idle speed: Readjust idle speed

Engine Stalls

• Improper float level: Readjust float level
• Leaking needle valve and seat: Replace needle valve and seat
• Vacuum leaks: Eliminate vacuum leaks

General Auto Repair

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