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Ryobi String Trimmer Won't Start

The string trimmersmall engine often has a separate model number. Use the small engine model number for a complete list of symptoms and parts. Watch our model # lookup video for help finding the model number.


The part(s) or condition(s) listed below for the symptom String trimmer won't start are ordered from most likely to least likely to occur. Check or test each item, starting with the items at the top of the page.

Most Frequent Causes for String trimmer won't start

Cause 1Carburetor

The carburetor might be clogged. A clogged carburetor is most commonly caused by leaving fuel in the string trimmer for a long period of time. Over time, some of the ingredients in the fuel may evaporate, leaving behind a thicker, stickier substance. This sticky fuel can clog up the carburetor and prevent the engine from starting. If the carburetor is clogged, try cleaning it with carburetor cleaner. If cleaning the carburetor isn’t effective, rebuild or replace the entire carburetor.

Carburetor for your RyobiString Trimmer
Carburetor - Part # 1951816 Mfg Part # 308054013

Carburetor for two-cycle engine. If the carburetor is clogged, the engine won't get enough fuel. As a result, the engine may not start or may run rough. The carburetor can often be cleaned or rebuilt, but sometimes it may need to be replaced.

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Cause 2Rewind Spring

When the starter rope is pulled and released, the rewind spring recoils the starter rope onto the rewind pulley. If the rewind spring is broken, the rope won’t be able to recoil onto the pulley. As a result, the engine won’t start. If the rewind spring is broken, replace it. Many rewind springs can be replaced individually, but it may be easier to replace the whole recoil starter assembly.

Rewind Spring for your RyobiString Trimmer
Rewind Spring - Part # 1954371 Mfg Part # 638033001

Homelite rewind spring (recoil spring) and container. If the rewind spring is broken, the starter rope won't retract.

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Cause 3Recoil Starter

The recoil starter assembly engages the crankshaft to turn over the engine. If the recoil starter assembly is defective, the engine won't start. Remove the starter assembly and inspect it to determine if it is working properly. When you pull the starter rope, tabs extending from the pulley and cam should grab the hub on the engine, causing the engine to turn. When you release the rope, the tabs should retract and the rope should rewind back on the pulley. If the recoil starter assembly is not working properly, replace it.

Recoil Starter for your RyobiString Trimmer
Recoil Starter - Part # 1951877 Mfg Part # 308194005

Starter housing assembly

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Cause 4Recoil Starter Pulley

The recoil starter pulley winds up the starter rope when the rope is not in use. If the recoil pulley is broken or stuck, it won't be able to rewind the starter rope. As a result, the engine won't start. If the recoil starter pulley is broken, replace it.

Recoil Starter Pulley for your RyobiString Trimmer
Recoil Starter Pulley - Part # 1953687 Mfg Part # 518501001

Plastic pulley - 26cc

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