[sunman]

This is a 86 Mustang EFI and the sender flange top of tank vent now connects to the purge valve and canister that’s controlled by the ECM.
Vents into intake for emissions control. Good for street cars.
Vent to atmosphere you smell gas and OBD2 throws codes.

My CR sealed cap filler neck drain line ran to another second fitting on top of tank. Didn’t use it tho now it’s a flush fuel cell cap.

I’ve driven Ford trucks with 302/5.0 for 40 years.
They usually limp home and a scanner tells you what’s wrong.
EEC IV system ECM fix is replace capacitors in power supply.

My 2007 Sport Trac 4.6 3V has 240K miles no problems.
The timing chain guides are plastic, changed at 200k miles.