Improving the fuel pump ground

The fuel pump and fuel tank sending unit ground at a sheet metal screw up behind the spare tire on an XJ, and behind the driver’s taillamp on an MJ.

Not only is a sheet metal screw a lousy way to ground things, this ground path is long and travels through some connectors that are prone to corrosion and moisture.

Locate the black wire on  the HARNESS side of the fuel pump/sender 3 wire connector. Remove a 6″ length of the split loom covering. Strip back about 1/2″ of insulation from the BLACK wire.1-fuel pump ground MJ

Take your new ground wire, preferably at least 14 gauge and 12 to 18 inches long as needed, strip it about 3/4″, and wrap it around the exposed part of the harness plug wire.1-fuel pump ground mj-002Solder the connection. Tape it up and reinstall the split loom covering.1-fuel pump ground mj-003

At the other end of your new ground wire, add a crimp on eyelet. Attach the eyelet under a bolt that goes directly into the chassis. Be sure to clean the attaching point til shiny and apply OxGard to the contact surfaces.1-fuel pump ground mj-004

Revised 10-16-2018



43 thoughts on “Improving the fuel pump ground”

  1. Appreciated! I came here from your link on jeepforum, and as I just replied there, I am wondering how to increase likelihood that this replacement pump will not fail as rapidly. was wondering if electrical ….something… might be contributing to failure problem.
    will change the ground this time, too.

    1. Gloria, a good ground for any Direct Current motor is very important to ensure motor longevity and peak performance. I have to ask what brand fuel pump you have currently installed.

  2. I’ll be doing it either way, but have you or anyone else had any luck with this helping the notorious inaccurate XJ fuel gauge? I’ve tried two different pump/sender assemblies and cleaned the contacts on the back of the cluster with no change. I know my range, but it sure would be nice 🙂

      1. I completed the ground about a few weeks ago – it improved the sensitivity of my gauge (needle moves going around corners/uphill, never did that before), but did not improve overall accuracy (gauge still reads close to E on 1/2 tank.)

        Still, can’t go wrong with more grounds! Thanks for the tip.

          1. Yes, I completed Tip 18 a while ago and noticed no change. Perhaps my sender assembly is just worn out, but I have often wondered if it is thrown off with modern ethanol blends/other additives not present at the time of the original design.

  3. When u say harness side u do mean the wiring harness for the jeep under the hood don’t u? Probably a dumb question but I did the tip a while back and around that same time is when I switched injectors and new fuel tank/filter but started having trouble with jeep not wanting to idle. So It crossed my mind maybe I did something wrong with the extra ground. By the way I didn’t soldier I used but connectors.

    1. In this case I’m referring to the HARNESS side of the fuel pump/gauge connector. The part that belongs to the vehicle, not the fuel pump. Not the side that’s part of the fuel pump assembly’s module. Under the vehicle.

      I never use butt connectors. Only solder, especially in critical areas.

      1. I guess what I mean is I know u are at the three wire plug near the fuel filter. However,. I still don’t understand which side of that plug? Would it be the black wire towards the front of the jeep or the rear of the jeep? I just went out now and looked at mine and I did the add in of the new ground on the black wire coming out of the frame. I will good back and solder soon. Wish I could send u a pic of what I’ve done.

        1. I am pretty sure from ur reply I am on the correct side of the plug I just need to solder my wires.
          Thanks for the help . This jeep detective work may turn me into a decent shade tree mechanic one day.

  4. The pump on my 89 just went out after 518,000 miles. So I replaced it with a JY Bosch from a Renix era rig that I had as back up ( for the past 10 years) in the spare tire rim.
    I have found that the OEM sensors and parts 25 years old, out perform most of the new stuff out there.

  5. Thanks for the fast reply! I’ve been working on my daily driver a 1988 pioneer 4×4. You have a great site with awesome info. I’ve done lots of the tips. Thanks for keeping this site up.

  6. I’m trying to find a way to get a new return fuel line. The hose section. What would I use considering that part is obsolete now and is not made anymore?

  7. ok sounds like a project, im going to see if john deere can make me one with the connectors on it. thanks a lot! pulling my pump and the internal hose was loose so my pressure was only 21 psi and the strainer and return check valve was gone… lol jeep life. dropping the tank to fish them out! fun stuff but the wife is jealous!

  8. Is there a return check valve on the fuel pump assembly? If so what would the part be called I’m having a heck of a time figuring it out. It’s kind of a cone shaped black piece on the return line in the tank.

  9. I spliced into the black wire, ran new ground wire to the fuel filter bolt. I did this on the tank side of the plug. 1. The fuel pump stopped working. 2. the new ground wire got very hot.

    1. Sounds like you chose the wrong side of the harness. I interpret the correct side as the one coming from the front of the vehicle. Example: If you were to remove your tank, you’d have disconnected and removed the tank-side end of the harness (because that “half” of the harness terminates into your pump/sender). In this case, you’d have only the front part of the harness remaining installed on the vehicle. That’s the one you splice from.

  10. Ever have the mj metal tank cause a short to the pump? I have two assemblies with pumps. One original to my truck since i bought it and one brand new. They run with a hot wire to the battery and hooked to the jeep OUTSIDE the gas tank. If i touch either to the tank at all. They won’t prime or run on trucks harness, or run on a seperate wire lead. Itll actually dead short the wire. But only.touching the metal tank. Otherwise it’s fine… Im not sure what this means. Here is a forum i started on comanche club.

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