Theoretical Question

[BigDog98]

Theoretically, can I just pull the engine kill switch to disable the ignition system when performing a compression test? And just use a vice grip to clamp shut the fuel line so no fuel gets pumped into the cylinders? Also is the proper procedure to pull all spark plugs and wires when doing the compression test or just pull each plug one by one and do the compression test as you go?

 

[Alumarine]

You don't say what you're testing but to answer your question as a rule.

Activating the kill switch should be fine.
Motor should be warm
Throttle wide open - no need to pinch fuel line.
Remove all plugs (mark the wires)

 

[Chris1956]

Or leave the ign key off and jumper the starter solenoid. If you jumper the starter solenoid, you can perform the compression test yourself, with a push in compression gauge.

 

[Texasmark]

Get a push button switch, a couple of alligator clips and 6' of 16 ga wire. Cut the wire in half and make a wiring harness with the switch centered. Hook one clip to the ⅜" input stud to the solenoid for battery voltage and the other lead to the hot small terminal on the solenoid. Push the button when you are ready to spin and another yes pull all the plugs.

 

[gm280]

Yes, some very good advice above. Removing all the plugs allows the engine to turn over without much resistance and therefore doesn't drain the battery as quickly. And since you are measuring each cylinder's compression, it doesn't matter either having them all removed.

 

[BigDog98]

So just to recap. I can connect a jump starter switch to the 2 posts on the slave selonoid and it won't actually start the engine, just turn the engine over so I can do a compression test ? And I won't have to disable the igntiton system or unplug the coil wire? Just will have to disable the fuel pump? I ordered the bump starter switch.

 

[harleyman1975]

If all plugs are removed the engine cannot possibly start.

 

[Maclin]

So just to recap. I can connect a jump starter switch to the 2 posts on the slave selonoid and it won't actually start the engine, just turn the engine over so I can do a compression test ? And I won't have to disable the igntiton system or unplug the coil wire? Just will have to disable the fuel pump? I ordered the bump starter switch.

The bump starter switch when connected properly can only turn the engine. No power to the ignition, fuel pump, etc. will be supplied.