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NotTaR of small Gasoline Engines and Rotary Lawn Mowers : Lawn mower will not start
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1994-2005, Samuel M. Goldwasser. All Rights Reserved. Reproduction of this document in whole or in part is permitted if both of the following conditions are satisfied: 1. This notice is included in its entirety at the beginning. 2. There is no charge except to cover the costs of copying.
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This is probably the most common problem you are likely to encounter.
The cause is very often the same - lack of maintenance.
Note that the assumption here is that it cranks - the crankshaft and blade
rotates in a normal manner but the engine never catches. Some larger (Briggs
and Stratton) engines may have a low-oil cutoff switch which will stop the
engine if the oil level is inadequate. However, this is not likely on a
push mower.
- In the case of a recoil starter, you are able to pull on the cord and the
crankshaft with the blade rotates and it feels normal but the engine does
not start. If it feels like nothing is engaging, then the starter mechanism
or clutch may be broken. Of course, if the cord breaks, then the problem
is obvious! See the section: Recoil (pull) starter
repair for more information.
- In the case of an electric starter, the engine cranks but never catches.
If there is no response to the button or key, then the outlet may not be
live, the battery may be weak or dead, or there could be a bad connection
or bad starter motor. If the motor spins but doesn't engage the engine,
the overrunning clutch or gear could be broken.
If you are unable to pull the cord (or the auxiliary starter on one with
electric start), there may be a clump of grass stuck between the blade and
the deck or there could be serious internal damage, especially if you just
encountered an immovable object. See the section: Lawn
mower will not start after the blade hit an obstruction. However, you
didn't forget to engage the dead-man bar, did you? On most inexpensive mowers
this safety interlock is needed to both enable the ignition system and release
the blade brake.