String trimmer or leaf blower won't start
Two-stroke trimmers and blowers stop starting for a few common reasons: old or wrongly mixed fuel, not enough priming, the wrong choke setting, a fouled plug or a clogged filter.
Step by step
Checks in order
Safety Do fuel work outdoors on a cold engine, away from sparks, pilot lights and cigarettes. Wipe up spills before starting.
| 01 | Empty the tank and mix fresh fuel at 50:1 with two-stroke air-cooled engine oil and 89 octane gas. | Don't use outboard (TCW) oil. Don't use E15 or E85. |
| 02 | Make sure the stop switch is in the run position. | |
| 03 | Press the primer (purge) bulb until fuel shows, then 4 or 5 more times on ECHO units, or at least 5 times on the STIHL FS 56. | |
| 04 | Set the choke to cold start for a cold engine. Once it fires, move it to run and keep pulling. | |
| 05 | Still nothing? Take out the plug. Wet means flooded: dry it and try again on run. Fouled or worn: replace it and set the gap. | Fouling usually means too much oil in the mix or a dirty air filter. |
| 06 | Clean or replace the air filter. | |
| 07 | Fish out the fuel filter in the tank and replace it if it is dirty. | |
| 08 | Cracked purge bulb or hard fuel lines? Replace them with the maker's kit. | On 2012 and later units, fuel hoses must be EPA-certified replacements. |
Plug and priming by model
Open the engine or model page for the full parts list.
| Model | Plug | Gap | Priming |
|---|---|---|---|
| STIHL FS 56 | NGK CMR 6 H | 0.5 mm | At least 5 presses |
| ECHO SRM-225 | NGK BPM8Y | 0.65 mm | Until fuel flows in the return line, plus 4 or 5 |
| ECHO PB-580T | NGK BPM8Y | 0.65 mm | Until fuel shows, plus 4 or 5 |
Engine not listed?
Send us the model number and we will look at adding it.