Sign | Probable cause | Method of elimination |
| Unstable engine operation | Fuel mixture too lean or rich | Repair or replace the carburetor |
| Fuel leaks from the retardation device | Replace | |
| The vacuum hose is not securely fastened | Secure the vacuum hose | |
| Defect in the pneumatic system for intake of heated air | Repair or replace | |
| Unstable engine idling | The tube from the air filter is disconnected | Repair or replace |
| The engine idle speed is incorrectly adjusted | Check ignition advance angle and adjust engine crankshaft speed at idle | |
| The air damper does not open fully | Repair or replace | |
| Fuel overflow in the carburetor | Repair or replace | |
| High or low fuel level in carburetor | Repair or replace | |
| The air intake pipe is clogged | Clean or replace | |
| The exhaust system is clogged | Replace the exhaust system | |
| Engine operation is not controlled | The carburetor is faulty | Repair or replace |
| The vacuum hose is not securely fastened | Secure the vacuum hose | |
| The fuel supply hose is dirty | Clean or replace | |
| The fuel filter is dirty or the check valve is damaged | Replace the filter | |
| Water in the fuel tank | Replace the check valve | |
| Incorrect fuel grade | Clean the filter and lines, fill with clean fuel | |
| Reduced engine power | The catalytic converter is damaged | Replace the catalytic converter |
| The air filter gasket is damaged | Replace the gasket | |
| The seal between the air filter housing and the carburetor is damaged | Replace the seal | |
| The intake manifold gasket is damaged | Replace the gasket |
[The text is taken from an online source: HyundaiBook]