The fuel pump link leads, or at least the ends of them are known to overheat and burn up.

But, what is in that matchbook size black plastic slab in the middle of the lead?

 

I have the same question under the thread, "Replacing fuel pump on 2002 XJR."

The wiring diagram from AllData shows nothing but the connector at the top of the evaporative unit. I'm trying to fit Denso pumps, and am not too impressed so far. The kit calls for splicing in the new pigtails with just standard butt connectors, offset so that they won't touch each other. I would feel much better with some shrink tubing to really isolate and seal them, but that calls for some special tubing that's hard to find. (Check out my post under the above mentioned thread.) I'm also having a hard time getting a good fit to the mounting bracket. I'm about to put the Densos back in the box, save them for the next time, and order a couple of OEM pumps.

 

The probable answer to the contents of the "black box":

Electric fuel pump RFI module with pre-molded housing - Walbro Corporation

Walbro holds a patent on a molded plastic radio interference choke for fuel pump applicatons.

If you read the bits about the grounding considerations, it may be a clue to why it is always the negative lead that burns up.

The same effect can be done externally using toroid coil windings.

It may also be that the leads can be sourced from Walbro.

 

Good job finding that information !! Which pumps are you using?

 

No idea yet.

The primary failed, I checked things out, pulled relay 4 to force the secondary to function at all times last night. Went for groceries this afternoon. Forgot a bag at the store. Went back. Secondary failed.

The tow bill totaled more than it was going to cost to do the job. The car is now at a shop because no tow truck can get to my usual parking spot. So now, labour charges are involved as well as not having the choice to be creative about which parts to replace.