I am trying to get a compression check on the cylinders of my Chrysler but having other issues. First, I have a brand new starting battery 625 starting amps measures 12.63 volts. Brand new starter measures 11.25 volts when cranking (not installed) installed measures 2.5 volts when cranking. I have cleaned and tightened all connections, checked for good ground. Here is the problem, when cranking with no plugs in starter turns over engine rapidly but when I put a plug in, it slows and stops and if I keep the battery attached, it will slowly rollover another compression stroke. Jumped the starter eliminating the solenoid same result; jumped solenoid from battery side to start terminal on solenoid, same result. Took battery off and cranked it measured volts at 11.25 while cranking. solenoid is working starter is working, but engine will not rollover enough to start or check compression. Basic troubleshooting is done, bad ground, poor or loose cable connections, bad battery, bad starter all eliminated as issues but problem persists. Does anyone have any experience with this problem? I've seen threads with the same problem but no one seems to have the answer. Hope someone can point me in the right direction...