1999 Force 40 HP - Compression Test

basstracker2008 · Jan 27, 2008

To all who has the patience to deal with a first time boater...

Below is what I did to test compression.
It describes the results and issues I encountered:

1. Run the engine to warm up. Turn off engine.
2. Remove the first spark plug and replace it with compression gauge.
3. Crank the engine.
4. The reading is 125 PSI.
5. Now when I moved to the next spark plug (bottom). I realized I have no enough room or space to insert my compression gauge.

As you can see above It is obvious that I need a detailed procedure on how to test, what results to expect and what tester is available to test the lower spark plug. See attached 2 pictures to see what I'm talking about.

http://i254.photobucket.com/albums/hh92/greatyear2008/DSC07432.jpg
http://i254.photobucket.com/albums/hh92/greatyear2008/DSC07434.jpg

steelespike · Jan 27, 2008

Re: 1999 Force 40 HP - Compression Test

I use a tester with a bent end it doesn't screw in so I have to hold it in place.
I think on that motor you need to be sure the plug wires are grounded when cranking.

JUSTINTIME · Jan 27, 2008

Re: 1999 Force 40 HP - Compression Test

take both plugs out also
do u have a gauge with a hose?
you need to ground out the plug wires or through the stop switch

JB · Jan 27, 2008

Re: 1999 Force 40 HP - Compression Test

Remove both plugs, leave the ignition OFF and jump the solenoid.

basstracker2008 · Jan 27, 2008