i have recentlly did a 88 5.0 swap into my bronco. used all the wireing from the mustang. hover did not hook up the fuel pump relay. i did install a in line fuel pump from a 86 f150 (new) put in new o2 sensors. it will sit and idle fine. when 1st put under load it will stumble and seem to back fire. and smells rich. then will clear up. went out and bought a fuel gauge for the schrader valve. not cheap. when running no presure is readable. after shut off unhook the gauge start up there is pressure for a instant. sorry for the long post but thought all the info might help. new to efi
Under load it takes more fuel. Pinch off the return line and watch the pressure, if it raises way up, change the regulator, if it doesn't, change the fuel pump and filter.
Not too sure, but doesn't the EFI bronco fuel configuration have two pumps like the F150? The tank has a feeder pump and the inline is just a booster. Running just the one it may be having problems drawing fuel out of the tank, or past the feeder pump if it's in the tank already and hooked inline.
Another thing for it running rich, unhook on the of the o2's and read voltage between the two white wires. Better be 12vdc or the o2 heaters aren't working and it will run like crap and very rich until you run it hard enough to warm them up.
it is a 74 bronco. so there is no intank pump. was going to work on this today but the rain is comeing down hard here. will try all of these later. thaks agian guys. will let you know later.