1999 Johnson 130hp compression test?

Been looking over the service manual and I got a question.

It says:

<snip..snip>

2. Disable the ignition system by connecting each spark plug wire to a
good engine ground (using a jumper wire from the ground to the wire inside
each spark plug boot). Never simply disconnect all the plug wires.
</snip>

Than in another paragraph it says:

<snip.snip>

*** Warning ***
Removing all of the spark plugs and cranking the powerhead can lead
to an explosion if raw fuelloil sprays out of the plug holes. A plug wire
could spark and ignite this mix outside of the combustion chamber if it
isn't grounded to the engine. Also, on many of the ignition systems
covered, cranking the engine and firing the coil without allowing the
coils to discharge through the spark plug leads can lead to severe
damage to the ignition system.
</snip>

So, am I to remove each spark plug from the wire and ground it or remove spark plug and
leave the wire connected and ground that?

if I was to leave the plug attached to the wire, Would I ground the electrode (center) to ground of just the threaded surface?
While performing this test, fuel would still be going into the cylinders so no need to worry about running dry cylinders?

Was concern about having fuel squirt out of the cylinders while performing the compression test and spark plug sparking away, outside fuel ignition!

Never did a compression test before on an outboard before nor an automobile!


Thanks.

Re: 1999 Johnson 130hp compression test?

If you are dong a compression test and not looking at spark then just pull out the emergency lanyard line as that stops any spark.

In regards to your other questions i ground the threads away from the rear sparkplug holes that are spraying fuel mix and i keep the sparks in the boot
I do mine warm, unless there is something wrong with the engine stopping that happening, keep fuel connected so it does keep the engine lubed

Re: 1999 Johnson 130hp compression test?

Look here. It isn't the only way, but it is a way that works.

http://forums.iboats.com/engine-frequently-asked-questions-faq/compression-test-jb-391323.html

Re: 1999 Johnson 130hp compression test?

This information is not from a factory manual.

Disable the ignition system by connecting each spark plug wire to a
good engine ground (using a jumper wire from the ground to the wire inside
each spark plug boot). Never simply disconnect all the plug wires.

Click to expand...

Good idea to keep from getting a good jolt and fire prevention...

Removing all of the spark plugs and cranking the powerhead can lead
to an explosion if raw fuelloil sprays out of the plug holes. A plug wire
could spark and ignite this mix outside of the combustion chamber if it
isn't grounded to the engine.

Click to expand...

Yep .....seen it happen.

Also, on many of the ignition systems
covered, cranking the engine and firing the coil without allowing the
coils to discharge through the spark plug leads can lead to severe
damage to the ignition system.

Click to expand...

Only on some foreign outboard systems such as Tohatsu ...

Re: 1999 Johnson 130hp compression test?

Pretty simple. Disable the ignition, remove all plugs, etc.