When it's in Start Mode, the Control Unit bypasses safeties like oil pressure and checking for output. When you release the switch into RUN, Control starts sniffing around for problems. I suspect it's either
1. Finding something actually wrong, and protecting you from the consequences or
2. Keeping you from having A/C because it thinks something's wrong that isn't
A bad fuel pump is always a possibility. There's probably a generic replacement that bolts right in. We had a BFA and I replaced ours with a little Purolator generic. There are "Standard (sometimes called High) Pressure" ones 5-7 PSI and "Low Pressure" more like 3 PSI. BFA calls for "Low" and it worked fine.
Do you have a Service Manual for BFA? I kept mine, and can scan the troubleshooting pages for you if you like. PM me with your email ID.
