That tool   looks pretty handy.

 A similar test............something that I do, that only takes a second to
hook up .......
with the engine idling, connect an inductive timing light to each spark plug
wire, one plug  wire at a time. .
Observe the flashing of the timing .
If it's a steady flash , that plug is firing.

if the spark plug is dead, the timing light won't flash.
or it it's intermittently flashing ....that plug isn't firing every time.
( related .......for a spark plug not firing every time - with an IR temp
gun, and engine running - read the temp of each exhaust pipe near the
cylinder head.
If a cylinder or two are reading say, 100 degrees F lower than the other
ones - that plug may not be firing well or full time. )

For an engine that won't run .......................... just remove a spark
plug,  plug it into its spark plug wire, ground the base of the plug  on the
engine with a large jumper wire.
Connect your Remote Starter Switch, turn on the key, crank the engine, and
watch how the spark plug fires.

if there's a good spark across the electrode gap - that's a good plug and
plug wire.
If there are tiny sparks jumping to the metal body of the spark plug, rather
than across the electrode gap ..
it's not firing correctly.   Clean or replace.

if plug wires are kinda old, and I find a plug not firing properly, I like
to replace both the spark plug and the spark plug wire for that cylinder.

Scott
www.turbovans.com

----- Original Message -----
From: "Katy Hahn" <ahwahneevw@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Tuesday, March 02, 2010 12:35 PM
Subject: Spark Plug Tester

>3 threads just today suggested that the spark be tested as part of
> diagnosing a non-start.
>
> Actually the traditional way to do this involves having a kid brother
> or possibly your mother-in-law hold the plug wire.  Failing that, I
> use one of these:
>
> http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=4424
>
> Pretty handy really.  They go on sale often for about 2 bucks.  Try it
> one time when all is well to get an idea what a strong spark looks
> like.