Don't be afraid to "unwire" the FItech so to speak and get it down to the power wires, and hot wire them direct until you get fuel and spark, then "re-add" the FI tech into the harness so to speak.
Go through the FI tech material and make a chart of essentials. For example does the box shut down spark if it does not see fuel pressure? If so, could that be an issue, etc. (example)
