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My current mower is a #10523 Gold Series 2-stroke I bought new in 1998.
Last Friday night I went out to cut the grass after dinner and she wouldn't start-no spark. I did a quick continuity check of the kill switch and guessing the coil was done, went to the computer to order a new coil. I don't ever remember replacing the coil on this one, so no shame if it was kaput after 19 years. After finding a NOS coil on eBay and doing a buy-it-now, I went back outside to put the mower away. After drying and re-installing the spark plug, I gave it a few pulls and it fired up. As daylight was quickly fading, I could only get the front yard done and reserved Saturday night for some mid-season maintenance in preparation for the new coil. When I pulled the coil out, I inspected it for any visible cracks in the coating or corrosion. Oddly, I found the spark plug connector terminal had a bit of rust inside the boot. I filled the boot with a few drops of metal-prep acid and after about 15 minutes, flushed it out with water first, then electrical cleaner. With a wire brush in a Dremel, I cleaned all the points of contact with the block, as well as the screw threads, wiped the flywheel clean, mounted the coil and set the gap. Too late to fire it up, so it sat overnight.
Sunday morning the grass was still wet, but I pulled the mower outside for a check and it fired on the second pull and ran fine for a few minutes, so plan "B", temporarily repossessing my other Lawn Boy that my son borrowed two seasons ago, was put on hold. Later in the day when the grass was dry I tried again, it fired on the first pull and ran without a hiccup to finish the rest of my yard, about 40 minutes of runtime total. I normally remove, clean and re-gap the coil every winter, but I don't remember cleaning the inside of the plug boot.
Who knows what next weekend will bring, but at least I'll have my spare coil by then. Has anyone experienced anything like this?

Bill

Corrosion resistance can be an evil thing, sounds like you solved the issue and coil is good.

Hi Bill,

It's possible it's corrosion, but coils that are bad, can work sporadically. I tried baking mine in a BBQ grill on low, but it failed again. I get my ignition modules locally from a company that also sells them on E-Bay for 12.00, a lot cheaper that the dealer who charges like 58.00.

Regards

Jeff

Thanks for commenting, Jeff.

As always, it's the intermittent nature of a problem that's so hard to diagnose. I put in a new E3 spark plug during my winter maintenance and the metal terminal on the plug was clean, but the plug wire terminal corrosion was the only visible defect, so I addressed it. As posted, I already ordered a NOS coil I found on eBay, so I'll install it for a test run and make sure it's OK, then put the original back in and keep the new one in reserve so I'm ready for the inevitable.
Funny thing is that I bought this mower back in '98, when I was at the local dealer to replace the failed coil on my '86 model. When I saw the 1998 models had changed so much with TORO influence, they made me a deal on the "leftover" '97, which the clerk said was likely the last "true" Lawn Boy. I was there to spend $50 and would up spending almost $500, and in retrospect I was happy I did.

Bill

Billy Jack said:

Thanks for commenting, Jeff.

As always, it's the intermittent nature of a problem that's so hard to diagnose. I put in a new E3 spark plug during my winter maintenance and the metal terminal on the plug was clean, but the plug wire terminal corrosion was the only visible defect, so I addressed it. As posted, I already ordered a NOS coil I found on eBay, so I'll install it for a test run and make sure it's OK, then put the original back in and keep the new one in reserve so I'm ready for the inevitable.
Funny thing is that I bought this mower back in '98, when I was at the local dealer to replace the failed coil on my '86 model. When I saw the 1998 models had changed so much with TORO influence, they made me a deal on the "leftover" '97, which the clerk said was likely the last "true" Lawn Boy. I was there to spend $50 and would up spending almost $500, and in retrospect I was happy I did.

Bill

Click to expand...

I have an 01 dura force with the original cdi, I bought it from a pile at a dealer, sitting out side for who know how long, ended up replacing the short block. I have an extra coil off ebay as well just in case. I also have the E3 plug in my lawn boy as well as my string trimmer, both seem to start easier, the trimmer runs much better with e3 (homelite 25cc).

At the component level coils can be made from parts that have never been run in the completed circuit. These are probably the ones in the $15 specials. So the buyer performs "burn in," the term for screening out weak components. Buying another like these is fruitless, although a person can get lucky . Coil makers who buy better grade parts pay more for them and pass the cost along. There are also grades of screened parts which can withstand higher operating temperatures . The better ones are "industrial" grade and "military" grade. But there is a limit to what the best can withstand and IMO the air cooled engines push the survivability margin , often past the limit (dirty/plugged finning, low oil) . The best bet is to pay the 2 to 3 times price, preferably with a Japan or US OEM branding. The intermittent and fail-at-hot behavior is common. When military grade parts are received at the big aerospace companies with certification they are typically run again to weed out weak parts and they do fail. Those failing at hot are sprayed with CO2 and usually start working again when "cold." Sermon over and hope it helped.

Wednesday update:
Still 80 degrees when I out after supper. Started on the second pull and ran without a stutter for the first ten minutes, at which time I stopped to switch to the mulching insert. Then, a single pull start and 30 more minutes of smooth running.
Sometimes, ya just don't know!

Bill