QuestionModel # 143986250 STP185U1G1RA I have a 5 year old craftman push mower(self propelled) that has set up since last spring '06. When I tried to start it last week I wasn't getting fire(I pulled the plug out and pulled the cord to start and it wasn't firing at all) How do I check between the coil for the problem or if it is the saftey switch?
AnswerRoy
You may have a cut off switch thats giving you the problem or the coil is bad.
Check the switch for the off handle thats the only one. If the coil is bad which it probally is sitting that long. Check between the terminals on the coils to see if it shorts out.
If your mower is less than 15 years old, there is an excellent chance that if uses an electronic ignition system. These are very reliable as there are no points or condenser to go bad and no need for routine tune-ups.
However, a number of other problems can result in lack of spark:
Make sure stop switch/stop wire is in appropriate position - confirm with a multimeter, check that flywheel is being spun by starter and that flywheel key is intact to assure proper timing, check condition of points/condenser and setting (if applicable), test magnet (on flywheel) for strength, check the gap between flywheel and magneto core. If these are all fine, test or replace the magneto.
In more detail:
Check for a faulty or misadjusted STOP switch. This may be activated by releasing the dead-man bar or by a throttle control lever (STOP, RUN, START). Inspect the cable, linkage, and wiring for damage or for something that may have come loose. Make sure you have the controls set properly to run!
Check that your starter is actually spinning the flywheel. If the flywheel is not rotating properly when you pull the cord or turn the electric start key, then there is a problem with the starter, not the ignition system. Or, the flywheel is not tight due to a sheared flywheel key or improperly torqued flywheel nut.
Check for a flywheel that is loose and not seating properly on the taper. This could result in no spark if the air gap between the flywheel magnet and magneto core is then incorrect. However, due to the close spacing, you would probably feel and hear serious scraping in this case.
Items (2) and (3) are likely if your just attempted to move a curb with your mower blade (or if someone inadequately tightened the flywheel nut during some previous maintenance).
Check for bad connections or defective wiring including faulty or water logged insulation. If you just gave the mower a shower, wait ample time for it to dry out. High humidity may result in more problems if the insulation is not in good condition as well.
Check for a weak (or missing) flywheel magnet. Both of these faults are extremely unlikely unless you have been hammering and whacking the crankshaft and flywheel in an effort to remove the flywheel. (This is not recommended - see the section: Flywheel removal.)
(a) Electronic ignition - There is likely a single potted module which includes the circuitry and ignition coil. If anything goes wrong with this module, replacement is the only option. Once the wiring and resistance of the secondary has been checked, there are really no addition tests that can be performed on an electronic ignition module without special equipment. A defective ignition module will have to be replaced.
(b) Breaker point ignition - Possibilities are bad, dirty, corroded, or loose points or points that are grossly out of adjustment, a bad condenser, or a bad magneto coil. See the section: Maintenance of point-type ignition systems.
