Too early to pull gas tank. Some of your story does not make sense. Please read your post. You say mechanical twice. I don't think you mean mechanical gets it started and mechanical keeps it going. Don't use the word "cranked". Cranked means when the starter turns the flywheel.
Just tell us what is wrong. What is your issue right now.

1. Does the motor start or not right now?
2. What fuel pumps are connected.
3. You don't need or want two fuel pumps. Stop using two fuel pumps.
4. If you were able to suck gas from tank, thru a long hose, by mouth......you don't have any obstruction!!!!
5. What cubic inch is the motor? What year is the motor?
6. Where exactly were you sucking on hose?
7. You need to do some testing when you are ready we will help.
8. Let us know what you have done, if anything, since last post today.

Answer the questions and comments in order. Be specific.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn