Troubleshooting
High rpm
Will not run at | Adjust H screw |
full throttle | Blocked air filter |
| Blocked fuel tank vent |
| Blocked fuel filter |
| Fuel line blocked |
| Loose or damaged fuel hose |
| Impulse channel leaking |
| Impulse channel blocked |
| Loose cover on carburettor pump |
| side |
| Faulty pump diaphragm |
| Leaking air intake hose (rubber) |
| Loose carburettor mounting bolts |
| Needle valve set too low |
| Metering system damaged |
| Metering system incorrectly |
| assembled |
| Leaking control diaphragm/cover |
| plate |
| Needle valve assembly sticking |
| Blocked silencer |
|
|
Low power | Adjust H screw |
| Blocked fuel tank vent |
| Blocked fuel filter |
| Impulse channel leaking |
| Impulse channel blocked |
| Loose cover on carburettor pump |
| side |
| Faulty pump diaphragm |
| Blocked air filter |
| Needle valve assembly sticking |
| Leak in metering system (air or fuel) |
| Metering system incorrectly |
| assembled |
| Loose diaphragm rivet |
| Hole in diaphragm |
| Leaking control diaphragm/cover |
| plate |
|
|
Will not “four- | Blocked fuel tank vent |
stroke” | Blocked fuel filter |
| Fuel line blocked |
| Loose or damaged fuel hose |
| Impulse channel leaking |
| Impulse channel blocked |
| Loose cover on carburettor pump |
| side |
| Faulty pump diaphragm |
| Leaking air intake hose (rubber) |
| Loose carburettor mounting bolts |
| Needle valve set too low |
| Leak in metering system (air or fuel) |
| Metering unit incorrectly assembled |
| Loose diaphragm rivet |
| Hole in diaphragm |
| Leaking control diaphragm/cover |
| plate |
|
|
Acceleration and retardation
Does not | Adjust L screw |
accelerate | Adjust H screw |
| Blocked air filter |
| Blocked fuel tank vent |
| Blocked fuel filter |
| Fuel line blocked |
| Loose or damaged fuel hose |
| Impulse channel blocked |
| Loose cover on carburettor pump |
| side |
| Faulty pump diaphragm |
| Leaking air intake hose (rubber) |
| Loose carburettor mounting bolts |
| Needle valve set too low |
| Metering system incorrectly |
| assembled |
| Needle valve assembly sticking |
| Faulty diffuser jets |
| Blocked silencer |
|
|
Engine stalls | Adjust L screw |
when throttle | Adjust H screw |
released | Faulty pump diaphragm |
| Needle valve set too high |
| Needle valve assembly sticking |
| Faulty diffuser jets |
|
|
Over rich | Adjust L screw |
acceleration | Adjust H screw |
| Blocked air filter |
| Faulty pump diaphragm |
| Faulty diffuser jets |
|
|
Troubleshooting methods
In addition to the faults described in the above table, trouble shooting can be carried out on specific components or
•Checking the operation of the chain brake
•Measuring the resistance of the stop plate
•Pressure testing the carburettor
•Pressure testing the decompression valve
•Pressure testing the cylinder
English – 11
