Hi, Allonsy, welcome to the forums! I have included Mopar EFI conversion installation key points in several articles at the magazine. Could not go into great detail because my Jeep CJ Rebuilder's Manual, 1972-86 and Jeep Owner's Bible each contain details on the installation of a two rail (earlier) system. (The Jeep CJ Rebuilder's Manual has actual installation steps, the Jeep Owner's Bible is a system overview.) Copyright does not allow me to reprint from my Bentley Publishers books. The CJ book would be valuable for your needs; if you have a 1987-90 YJ Wrangler, the fuel pump replacement article (shared in links below) would be a helpful supplement.
There are two basic Mopar EFI systems. (Actually three, if you include the original Mopar throttle body conversion system with Electromotive components and a Holley TBI unit, available in the early 1990s from Mopar Performance.) Of the two Mopar EFI/MPI systems, the earlier MPI version patterns from a 1994-95 Jeep YJ Wrangler or similar XJ Cherokee 4.0L, and this is a two rail system with a return line to the fuel tank from the engine. The pressure regulator is at the engine. This system, uniquely, uses mostly off-the-shelf Jeep YJ or XJ parts.
The later system is similar in many ways but is a single rail design with 1997-up TJ Wrangler and XJ Cherokee 4.0L off-the-shelf parts. This system has a regulator that mounts near the fuel tank. The modified regulator is essentially the (1997-up) TJ and XJ fuel pump module's regulator. Single rail systems regulate fuel at the tank (or an externally mounted regulator in this kit), with only one fuel line going to the EFI rail at the engine.
If you're either troubleshooting an existing system or need details on the kits, see my links below for some highlights. I am pleased to answer questions about these EFI/MPI systems if you're in a troubleshooting situation. Post your question(s) at the forum, I'll be glad to answer. Meanwhile, these articles should be helpful.
See these articles:
In this installation for an '87-'90 YJ Wrangler, I use the Mopar factory fuel pump module with an MPI conversion. The "kit" comes with an externally mounted fuel pump. This alternative, using the higher pressure designated pump for MPI, works with these models. For a 1980-86 CJ, there is no provision for the in-tank fuel pump module, and you need an external fuel pump, mounted near the fuel tank:
Jeep in-tank fuel pumps can be difficult to troubleshoot and service. In this article, Moses Ludel discusses fuel pump diagnosis, repairs and pump replacement steps.
Each of these articles will help explain or illustrate various features on the Mopar EFI/MPI systems. You'll find some installation notes, too. The step-by-step installation for an '80-'86 CJ (similar in many ways to the 1987-90 4.2L YJ Wrangler install) is in my Jeep CJ Rebuilder's Manual: 1972-86. If you want specific answers about your project, just ask here at this forum:
The Jeep inline six stroker motor with EFI or MPI develops maximum performance when tuned properly. Selecting the correct MPI injectors and matching the fuel supply system to the bigger engine and higher horsepower output require the modifications described here.
Here, I do an overview of the various aftermarket EFI systems, including Mopar MPI:
In this coverage, we install the MSD Atomic EFI system on a Jeep 4.2L inline six-cylinder engine. The retrofit is similar for all Jeep 258 engines built from 1971-90. See detailed how-to steps for this 1989 Jeep YJ Wrangler installation.
Should you convert your 4.2L Jeep inline six to EFI? In this feature, Moses Ludel contrasts the BBD carburetor and the Mopar Performance EFI conversion kit.
Fuel pump and system pressure is different for carburetion, TBI and MPI. In this article, Moses Ludel discusses fuel pressure requirements for various Jeep engines and chassis designs.
Trust this helps, Allonsy! Please share details about your project...Looking forward to your participation at the forums...