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I recently got a 1989 Jeep YJ that sometime in the past, had the Mopar 1994 FI conversion installed on the engine.  While the Jeep came with a lot of documentation about the other work done on it, there was only one page concerning the FI conversion.  The problem that I am running into is this:  If the alternator is hooked up correctly, the engine won't turn off by using the key.  If the alternator is not hooked up correctly (meaning that it's not charging) the key shuts off the engine.  I thought that it might of been a bad ignition switch, but after changing out the ignition switch, the problem is still there.  I have gone through the wiring, removing the old and abandoned wiring, also with no luck.  I am wondering if someone knows where I can get the installation instructions and the wiring diagram for the 1994 FI conversion?  I'd like more information on the FI conversion and also follow out some wiring to make sure someone didn't install a wire in the wrong place.

 

 

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Hi, HighDesert...HESCO at Birmingham did R&D work for the Mopar EFI conversion, and HESCO remains a key source for the unique (non-OEM) EFI kit components.  

As you note, there were two kit varieties, each follows the factory OEM parts layout for either a 1994-95 (two-rail EFI type) or the later (single rail) 1997-up 4.0L prototype.  The wiring harness furnished with either of these kits should not impact the alternator current flow or create an issue with the ignition circuit.  

I'm suspect that someone has fiddled with the alternator wiring circuit or that there is a mix-up in the wire routing for the EFI harness.  Or perhaps the EFI kit's wiring harness was not used?  Or there may be a short between wires within a wiring harness.

There is a very simple interface, four or so wires, between the Mopar EFI conversion kit's wiring harness and your Jeep YJ Wrangler chassis wiring.  The EFI kit's ease of installation was largely due to this conversion wiring harness provided.  The PCM on your kit is the common 60-way/pin type found on a 1991-95 Jeep YJ or XJ vehicle with the 4.0L inline six.

Contact HESCO (Hurley Engine Service Company at Birmingham), they likely have the earlier kit's instruction sheet in PDF form (maybe even downloadable).  The tech staff could also have a quick insight into your wiring issue.

Let us know the cure...

Moses

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