Small Engine Lookup

Lawn mower engine won’t start: manufacturer checks in order

Reviewed 8 primary sourcesSee sources

Most no-start causes the manufacturers list are simple: a control left off, old fuel, or a dirty or loose spark plug. Work through them in this order before taking the mower in.

Checks in order

  1. Check the controls

    Honda’s owner’s manuals start with the controls: fuel valve on, choke closed on a cold engine, and the flywheel brake lever or stop switch in the run position. On electric-start engines, check the battery and fuse.[5][6]

  2. Check the fuel

    Make sure the tank has fuel and that it is fresh. Briggs & Stratton says gasoline can start to break down in as little as 30 days; drain last season’s fuel and refill.[1][5]

  3. Check the oil level

    Kohler lists an incorrect oil level as a no-start cause, and Honda GX engines with Oil Alert stop or will not run when the oil is low.[7][6]

  4. Check the spark plug

    Make sure the plug lead is attached, then inspect, clean or replace the plug and set the gap. A plug wet with fuel suggests the engine is flooded; Honda says to dry it and start with the throttle at fast.[1][5]

  5. Check the air filter

    Clean or replace a dirty air filter: foam elements can be washed, paper elements are replaced.[2]

  6. Narrow it to fuel or spark

    Briggs & Stratton suggests removing the plug after a few pulls. A dry plug points to a fuel problem, often a carburetor clogged by stale gas; a wet plug means fuel is arriving, so check for spark with a spark tester.[3]

What the symptom can point to

Deeper causes

If the simple checks fail, the manufacturers list a clogged fuel filter or line, a dirty carburetor, a faulty ignition module or kill switch, low compression and stuck valves. These need a carburetor rebuild, ignition tests or a dealer.[4][8][5]

When to stop and book a repair

Related

Sources

Facts on this page are restated from the documents below and linked to the publisher. Check the document for your exact model before relying on a value.

  1. Top 5 mower troubleshooting tipsBriggs & Stratton · “Your mower won’t start” and “You lose power in the middle of mowing” · retrieved
  2. 5 mower troubleshooting tipsBriggs & Stratton · “Inspect the air filter” and deck-clearing steps · retrieved
  3. How to troubleshoot your mower not startingBriggs & Stratton · Video description: spark plug and spark tester steps · retrieved
  4. Small engine problem solving tipsBriggs & Stratton · Starting, carburetor and exhaust-smoke sections · retrieved
  5. Owner’s manual GCV160 · GCV190American Honda Motor Co. · 00X37Z8B 0029 · English section: safety pp. 5–7, fuel and oil p. 7, maintenance p. 8, problems pp. 9–10, specifications pp. 10–11 · retrieved
  6. Owner’s manual GX120 · GX160 · GX200American Honda Motor Co. · 00X37-Z4H-6100 · English section: fuel and oil p. 8, reduction case p. 10, air cleaner pp. 11–12, spark plug p. 12, problems p. 15, specifications pp. 18–19 · retrieved
  7. XT650, XT675, XT775 owner’s manualRehlko (Kohler engines) · 14 590 36 · Safety p. 2, high altitude p. 4, oil chart and maintenance p. 5, fuel p. 6, spark plug and air cleaner p. 7, troubleshooting and specifications p. 8 · retrieved
  8. XT series service manualRehlko (Kohler engines) · 14 690 01 Rev. G · Identification p. 5, troubleshooting guide pp. 13–14, carburetor causes p. 20, spark plug table p. 27 · retrieved

Primary publishers: Briggs & Stratton, American Honda Motor Co., Rehlko (Kohler engines). Spotted an error? Email the address in the footer with the model and the document you are using.