Grounding plugs to test compression

[buddyp]

My 35 johnson kill switch is inoperative...so to test compression I have to ground each plug seperatly or all together? Plugs in boot ..each plug grouned seperatly oor together? What will happe if I do not ground the plugs?

Thanks

 

[pbgeneral]

Re: Grounding plugs to test compression

I don't know if this is correct or not, but when I do my compression check, I remove one plug at a time and ground that lead with an air gap tester while I do the compression test. I would in your case disconnect all boots from all plug to avoid a start up since the kill switch is bad.

 

[Daviet]

Re: Grounding plugs to test compression

You can use a multi-spark checker to ground the spark while doing a compression. You can also use a remote starter button on the starter solenoid and leave the key in the OFF position, then you don't have to worry about the ign system.

 

[JB]

Re: Grounding plugs to test compression

To do a compression check safely, disable the ignition, as recommended above. The simplest way is to leave the key OFF and use a jumper to operate the starter.

All plugs should be removed during a compression test.

Complete instructions are in the Engine FAQs Forum.

Testing for spark is a different issue and a different procedure. It is dangerous to mix them.