Can I replace the factory fuel pump on a 86 Nissan p/u with an inline unit?

Yes it can, it is done all the time, but be certain that the replacement will maintain the minimum required pressure for your fuel injection.

Also be very certain that you wire the pump into the circuit controlled by the pcm.

Be careful to install the pump up high inside the frame so that it is protected from damage. Also make sure that the plumbing is is secure and leak free. You can cut into the SUPPLY side of the original plumbing, but do NOT cot or alter the return line. It is necessary for the fuel system to retain that part. Do NOT alter the EVAP plumbing, as it can cause performance problems and cause the little trucklett to fail its emissions test.

Good Luck

You must have the "hardbody" version of the '86 Nissan. If you weren't aware, there were two '86 Nissan trucks. The first was the Datsun version with four headlights. Later in the year is when the hardbody was introduced. Mine was the earlier version and came with an inline fuel pump, not an in tank pump. It was located on the frame rail just behind the cab on the passenger side. I think you would have no problems converting to this type of pump. Much easier to deal with. I did replace my fuel pump with a cheaper aftermarket pump from O'Reily and had no problems. You can probably just order one for an '86 truck. It came with the pump and an inline filter for about $20.00. You will just have to work out the mounting part, but i wouldn't think it would be too hard, just somewhere along the fuel line.

Good luck

Probably. Try it. A universal pump is like $32 at Autozone.