I ve highlighted the wiring portions of each item of the swap in bold text. That way, when you re crawling around under your Jeep, getting greasy fingerprints all over a print out of my lovely article, you can still find the wiring info while simultaneously cursing my name and crimping wires. The fuel pump is a good place to start. From 87 to 90, all Wrangler 4cyl Jeeps used a TBI injection system with an in tank pump that was physically identical to the MPI pump used in all 4cyl and 6 cyl. Jeeps built from 1991-1995.
Dark blue goes to the sending unit.
For all swaps you will need a fuel filter. It ll be nice to know that your stock motor mounts bolt up to the 4.0L motor. It s a simple down-pipe that needs to be bent and you may, or may not need to have the o2 sensor bung moved to make room for the new down pipe. If I ve got any issues with Chrysler engineers, this takes the taco. This means you can t substitute your flywheel or flex plate from your 258.