Hi and thanks for using 2CarPros.
Honestly, it sounds like a bad ground. Reconfirm that the battery terminals are clean and tight, the ground to the engine is clean and tight as well as other grounds from the battery (There are a total of three) and make sure the connections at the starter are tight. I have a feeling when installing the new engine, one of the body grounds were damaged.
I attached two pictures of the starting system. I overlapped them so you could follow them. Note the three body grounds. Also, note fuses.
Let me know what you find or if you have other questions.
Take care,
Joe
Images (Click to make bigger)
SPONSORED LINKS
Thursday, January 24th, 2019 AT 6:19 PM