When you say the battery was behind the seat, it was disconnected, correct? Or did you run extremely long cables?
Now, the idea that the gauge indicates 11v, is low. When cranking, I'm sure it drops a good bit. You need approximately 9.7v for the ignition to work correctly when cranking. Do you have that? Also, when you had the engine running, how many volts were produced by the alternator? It should have been between 13v and 15v.
Let me know.
I attached a pic below showing how the body, engine, and frame grounds are made. Confirm that is what you did.
Also, if you could, record it cranking and upload it for me to hear.
Friday, May 12th, 2023 AT 9:39 PM