Starting issue

[Daeron]

I have not confirmed that I am getting at least 12v to the solenoid when the problem occurs, I will confirm that tonight. Just to be clear, if I use a multimeter and measure the dc voltage at the positive side of the solenoid while the key is in the cranking position, it should be at minimum 12v, correct?

 

There are two "solenoid terminals" on your starter. One is a large stud (6mm diameter?) with a 10 mm nut on it that your battery cable connects to, and the other is a small square male terminal that gets a skinny wire from your car's wiring harness (ultimately from your keyswitch) originally, but with the relay modification, that skinny wire should be coming from your relay now.

 

The lug on the solenoid connected to the battery cable should see full battery voltage at all times. That means, if your battery measures 12.55v but the other end of your battery cable only measures 12.1v, you have a problem. 12.1V would be enough on the little tab (because that circuit doesn't need a whole lot of current, that is just closing the solenoid.) but if it drops that much going through your positive cable, then the cable is a problem. The solenoid is itself just a glorified relay to operate the starter motor, in addition to pushing the gear forwards to engage the flywheel. So anything significantly less than full battery voltage into the big lug with the 10mm nut on it is a problem, but the other solenoid terminal simply needs a good 12 volts. Is that clear, or was I a little confusing?