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Re: [Shop-talk] It's A Simple Machine, Right?

To: "shop-talk@autox.team.net" <Shop-talk@autox.team.net>
Subject: Re: [Shop-talk] It's A Simple Machine, Right?
From: Jeff Scarbrough <fishplate@gmail.com>
Date: Sun, 6 Jul 2025 06:59:39 -0400
Delivered-to: mharc@autox.team.net
Delivered-to: Shop-talk@autox.team.net
References: <CAO8Q7CO28uMFK_qVdDwZ-OBk=87gcF1_c=qreESced_OnJtt5w@mail.gmail.com>
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Update:  On Thursday, we tried a new plug - no start.  Pulled the flywheel
bolt and inspected the key - perfect alignment (did not remove the flywheel
to visually inspect the key itself).

New coil on the way - interestingly, direct from Briggs & Stratton was
cheaper than buying a B&S-labeled part from Amazon, and presumably has a
far better chance of being both the correct part and not counterfeit.


The saga continues...

On Wed, Jul 2, 2025, 14:31 Jeff Scarbrough <fishplate@gmail.com> wrote:

> I've got a puzzle...
>
>  tl;dr - should I try the plug first, skip ahead and replace the coil, or
> is there something else I should try?
>
> The patient is a Snapper rear-engine riding mower, a machine that's as
> simple as can be.  Powered by a B&S Intek 12.5 HP engine, another simple
> machine.
>
> My friend was cutting his grass and managed to get the grass chute tangled
> up in some old fencing.  He got it loose, and continued to mow.  After a
> short distance, the mower quit running and would not restart.
>
> I brought it into my shop and we started troubleshooting. I first tried
> ether - it seemed like it tried for a second, and then nothing.  Pulled the
> plug and it looked wet.  Turned the engine over with the plug connected and
> grounded, and observed a spark.  Not a magnificent spark, but a spark.
>
> Verified compression, but due to the position of the muffler, I could not
> get *any* of my compression testers to seal in the hole well.  But it
> pushed against my finger with some force.
>
> Moved to the carb.  Pulled and inspected.  Float working, jet clear.
>
> Put it all back together, and nothing.
>
> Pulled the ground wire off the magneto coil and no change.
>
> So, I'm thinking weak coil.  Not completely dead, but not working under
> cylinder pressure.  Something else I read suggested a bad plug - this one
> was installed a month ago and has been working.  Date code on the engine
> indicates it was built on April Fools Day, 2008.
>
> In the era of $15 lawn mower coils, I would throw one on with no qualms.
> But at $40 or $50, I hesitate.
>
> So,  tl;dr - should I try the plug first, skip ahead and replace the coil,
> or is there something else I should try?
>
>

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<div dir=3D"auto">Update:=C2=A0 On Thursday, we tried a new plug - no start=
.=C2=A0 Pulled the flywheel bolt and inspected the key - perfect alignment =
(did not remove the flywheel to visually inspect the key itself).<div dir=
=3D"auto"><br></div><div dir=3D"auto">New coil on the way - interestingly, =
direct from Briggs &amp; Stratton was cheaper than buying a B&amp;S-labeled=
 part from Amazon, and presumably has a far better chance of being both the=
 correct part and not counterfeit.</div><div dir=3D"auto"><br></div><div di=
r=3D"auto"><br></div><div dir=3D"auto">The saga continues...</div></div><br=
><div class=3D"gmail_quote gmail_quote_container"><div dir=3D"ltr" class=3D=
"gmail_attr">On Wed, Jul 2, 2025, 14:31 Jeff Scarbrough &lt;<a href=3D"mail=
to:fishplate@gmail.com">fishplate@gmail.com</a>&gt; wrote:<br></div><blockq=
uote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc =
solid;padding-left:1ex"><div dir=3D"ltr">I&#39;ve got a puzzle...<div><br><=
/div><div>=C2=A0tl;dr - should I try the plug first, skip ahead and replace=
 the coil, or is there something else I should try?<br><br>The patient is a=
 Snapper rear-engine riding mower, a machine that&#39;s as simple as can be=
.=C2=A0 Powered by a B&amp;S Intek 12.5 HP engine, another simple machine.<=
br><br>My friend was cutting his grass and managed to get the grass chute t=
angled up in some old fencing.=C2=A0 He got it loose, and continued to mow.=
=C2=A0 After a short distance, the mower quit running and would not restart=
.<br><br>I brought it into my shop and we started troubleshooting. I first =
tried ether=C2=A0- it seemed like it tried for a second, and then nothing.=
=C2=A0 Pulled the plug and it looked wet.=C2=A0 Turned the engine over with=
 the=C2=A0plug connected and grounded, and observed a spark.=C2=A0 Not a ma=
gnificent spark, but a spark.=C2=A0=C2=A0<div><br></div><div>Verified compr=
ession, but due to the position of the muffler, I could not get *any* of my=
 compression testers to seal in the hole well.=C2=A0 But it pushed against =
my finger with some force.</div><div><br></div><div>Moved to the carb.=C2=
=A0 Pulled and inspected.=C2=A0 Float working, jet clear.</div><div><br></d=
iv><div>Put it all back together, and nothing.=C2=A0=C2=A0<br><br>Pulled th=
e ground wire off the magneto coil and no change.<br><br>So, I&#39;m thinki=
ng weak coil.=C2=A0 Not completely dead, but not working under cylinder pre=
ssure.=C2=A0 Something else I read suggested a bad plug - this one was inst=
alled a month ago and has been working.=C2=A0 Date code on the engine indic=
ates it was built on April Fools Day, 2008.<br><br>In the era of $15 lawn m=
ower coils, I would throw one on with no qualms.=C2=A0 But at $40 or $50, I=
 hesitate.<br><br>So,

=C2=A0tl;dr - should I try the plug first, skip ahead and replace the coil,=
 or is there something else I should try?<br><br></div></div></div>
</blockquote></div>

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