There is a regulator on the fuel rail.
This isn't going to be easy, (on me that is). In the past I have read posts where people have done what you are about to do, some with good luck, most with not such good luck.
To begin, you are going to have to install a return line to the tank from the fuel rail on the engine, no mater what pump you use. That pump needs to develop at least 40 pound of pressure to get the engine to run.
Next, in 86 when the B2's became injected they had 2 fuel pumps, (I would guess that Ford didn't have the technology at that time to do it with one pump), one pump in the tank for feeding the high pressure pump mounted on the frame rail under the drivers feet. The pump in the tank has always been a real problem, you have to drop the tank to change that pump, they don't go out too often, but when they doo, you are looking at a four plus hour job to change it. I have fixed that problem by cutting a hole in the rear floor of the B2. I'll go into that later.
I am rejuvenating an 86 B2 by using a 92 Explorer for a donor, it has made life somewhat simpler than having to go to the wrecking yard for all the parts. And having a vehicle that is already injected made life even easier than yours.
Installing an electric pump of any make on the frame rail is a hit and miss, some have had it work out, but most have not, as trying to pull fuel from the rear to the pump puts a real strain on the pump, so most have had to install an in-tank booster pump to keep from burning out the inline prematurely. That involves running wiring from the front pump to the rear, dropping the tank, installing the in-tank pump from an 86-90 B2.
When I started my project, one of the things I had to do was replace the in-tank pump and clean the tank, that meant dropping it, I did it, while I had the tank out I was trying to figure out a way of eliminating the second pump on the frame rail, at that point I had no idea what to do.
Now, however, that has changed. I have installed the in-tank pump from the 92 Explorer and removed the pump on the rail, all seems well.
What I suggest, and it is only a suggestion, get an in-tank pump assembly, (that comes with the sending unit) for a 86-90 B2 and just the pump itself, for a 92 Explorer, (91-95 i believe will work, you can find them online) and swap the stock B2 pump for the Explorer pump and install it into the tank. The plug for putting power to the pump can be purchased from this link:
http://www.jcwhitney.com/jcwhitney/...8976&shopid=100001&pageid=12&_requestid=26450 for the wiring schematic post a request or try to find it in a manual.
You will also need to change the sending unit from your existing unit in the tank to the new unit, fairly straight forward. Ford changed the ohm rating between some years, I don't know when it was, but to be on the safe side, change it.
GET 2 FIRE EXTINGUISHERS!!!!!!
Now to the fun part, cutting a hole above the tank sending unit. First and for most, make sure you cannot smell, see, feel, or any other sensory, GAS. Crawl under the rear of your truck, in front of the rear axle and look up and back from the differential, you should see a line coming from the tank and a black corrugated split loom, use something to push the split loom down and hold as close to the tank as possible, (wedge it in). Next, put the back seats down, remove the strip that holds the carpet in place at the very rear and remove it, roll the carpet forward and remove the piece under it, then on each side and the center of the carpet in front push it forward and remove the carpet, also remove the piece that held the front of it in place. You should now see a bare floor with 9 ribs running lengthwise, go to the center one and place a mark with a felt marker, then go about 4 inches on each side of that rib, that should put you on the top of the next rib, and put another mark. To the front, where the slope to where the rear seats mount, measure back about 5 inches and place another mark, (The piece of tin that held the front of the carpet was screwed down in the middle, you will want to cut an inch or so behind that screw hole). and another 8 inches and another mark. Connect all the mark to form a square, or rectangle, this is what you are going to cut out, I used a grinder with a cut off disc. Take your time and cut just deep enough to get threw the metal. When the cutting is completed and the piece removed, you should be looking down at the top of the sending unit.
Clean the top of the tank to get rid of the years of dirt buildup, paying close attention to the top of the sending unit. Unplug the wire and the fuel line, or lines, it may have 2, and using a hammer and screwdriver, remove the lock ring by tapping it around, hint-the tabs on the ring that fit under the tank tabs, have a stop, turn it the other direction, (don't laugh, a fellow I know, ruined his tank because he didn't pay attention) remove the sending unit from the tank, swap the fuel gauge sending unit to your new pump/sending unit assembly and reinstall the assembly in the reverse of the removal.
Now you need to route your return line from the engine back to the tank. The wiring portion of the job is going to require you to use a schematic for a 86-90 B2 and the donor vehicles wiring harness, (the wiring harness for the engine you have) you will also need an inertia switch if you don't already have one.
To replace the plate you cut out of your floor, either cut a larger corresponding piece from another rig or add a lip around the outer edge to support the cutout piece, silicone and screws or pop rivet in back in place and reinstall the items you removed to get to the floor.
I think I got it all, if I missed something, pos your ? here, PM or email me, I'll try to get it right.
To all B2 owners. If you haven't had to remove your fuel tank you don't want to. It took less time to get to the sending unit/pump assembly by cutting the floor out and patching the hole for a later removal, than it does to remove the skid plate and get the wiring/fuel lines disconnected.
Ray