Force Compression Test..help

[Bigprairie1]

Ok,
I'll repost this in the right spot. 1st...I'm new here so bare with me. I've recently purchased a 1990 18' bayliner with a Force 90 on it...with something less than 300 hours on it. Seems to run well so far but that is purely with the 'muffs' on....no water test yet. The previous owner said it always ran well for him.
Anywhooo, I'd like to do a compression test on it and would like to know the best place to start. How do I disable the coil/ignition to keep it from firing and starting? Should I disconnect or 'pinch off' the fuel during the compression test?
Any other pointers on this would be greatly appreciated.
Many Thanks!!!!
Bigprairie at ya'

 

[12Footer]

Re: Force Compression Test..help

Welcome to iboats, Big.
Run a good, solid ground to each plug wire from each plug wire to the head. doing so will prevent starting, keep you from getting zapped, and provide vital protection for the expensive switchbox... Floating HV potential will destroy them.

 

[roscoe]

Re: Force Compression Test..help

Just trip the safety lanyard, that will ground out the ignition.
Don't pinch off the gas.

 

[dkgrady]

Re: Force Compression Test..help

Do the test on the engine warm with gearbox disengaged (neutral) and accelerator at wide open throttle.

Dennis

 

[Bigprairie1]

Re: Force Compression Test..help

...near perfect feedback.
The idea with tripping the 'kill switch' sounds very good...and wow simple. Hopefully I'll be able to do this over the weekend.
All good info and feedback tho'.
Many Thanks!!!!!!

 

[Frank Acampora]

Re: Force Compression Test..help

You don't even need to use the ignition switch! Leave it in the off position. Just use a jumper from the battery positive connection at the solenoid to the yellow wire on the solenoid. It will crank without starting. It will spark a little but this can be minimised by quickly and firmly pressing the wire to the terminal. Use something around 12 - 14 gage wire. I use two screwdrivers crossed.
And you will be right at the back to watch the gauge--no running back and forth--no need for an extra person. Just be sure to crank at least 4 revolutions.