checking my compression?

[t16j10]

i have a 2001 saltwater series 250 mercury efi. can anyone walk me thru checking compression on my cylinders. my buddy has the guage, i just want to make sure i am doing it right.<br />thank you

 

[Scott Hall]

Re: checking my compression?

Warm up the motor on the hose for 10min,pull all the plugs,turn the kill off so the motor turns over but won't start! Install the gauge and crank the motor for 3sec,then check the psi. Record all six,if any are 8psi or more diffrent in psi you need rings,some say 10psi. I did my 2000 merc 175 efi and all were 115psi on the button!