I need some help. Fuel pump issue.

1988 XJ. Fuel pump wasn’t working. Everything checked out good, so I pulled the pump. The ground lead was rusted apart so I fixed it. Jeep ran fine on a test drive. Went out 30-45 minutes later and it will prime but not run. Soon as engine sputters it dies. Replaced the ballast resistor still just stumbles and dies. Pulled pump out again, while plugged up out of tanks the pump functions fine. Put it in fuel and it primes once and that’s it. Drain it, it primes again and that’s it. Could this just be a weak pump that needs replaced?

That rusted ground lead probably didn't do the pump any good while it worked its way to rusted out entirely. Figure that had to have been a poor connection for a while, meaning high resistance, which means higher temps for the fuel pump motor. I would vote for replacing it.

It is worth a check to test your fuel pump wiring circuit before swapping out the pump.

The wire on the starter relay orange/black on the connector marked BAL is a straight shot bypassing the fuel pump relay and ballast resistor to your pump.

Put battery voltage to that wire, unplug the fuel pump and test voltage to a good ground at the pump. Should also be a an orange wire. You can also test for voltage with the pump connected, there will be some loss, the pump draws current, but radical voltage loss may indicate a pump problem.

Somewhere around five connectors between the power source and the pump any one of which can partially cook or seriously corrode and cause a voltage/amperage loss. The harness runs under the drivers side kick panel and over the wheel well. Be careful the wire color can change between connectors, sometimes the wiring doesn't match the book.

A new pump may cure your issues, but still may not be getting full voltage/amperage.

The ballast resistor cuts back on voltage to the pump when the motor is running, the starter relay bypasses the resistor during cranking to supply a little extra boost. Jumping or deleting the ballast resistor has never hurt anything I've noticed.

as 8mud points out, there are multiple connectors that can affect power and ground to the pump. I would test the voltage at the pump and for sure perform this little trick outlined below for the ground circuit.

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