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Welcome to the forums, Dean...I am assuming that you're listening for the fuel pump from the same location, whether the doors are open or not...If the pump is not operating unless the doors are open, you have an open in the fuel pump circuit related to the door wiring, window/door lock switches or the vehicle's security system.

This could be a faulty factory or aftermarket security system or door window/lock switch that is interrupting the circuit to the fuel pump.  Do you have a security system that could be cutting out the ignition circuit when the doors are shut?  If so, this is the first trouble spot to consider.  

Beyond this, has your wiring been tampered with?  Is there a sign that the door jamb wiring to or from the door switches is shorting or has a voltage drop from an abnormally high amperage draw (a defective door switch, faulty interior lamp wiring, etc.)?  The power distribution box wiring could be getting a large amperage draw or voltage drop from the door wiring or a defective door lock/window switch.  We've covered the door switches for the XJ Cherokee at the forum, they are notorious for failing over time.  Do a forum search box hunt under "All Content", using the keywords "door locks" or "power windows".

Check the fuel pump relay and its socket terminals to see whether they function properly and can get current to the pump.  This could reveal a voltage drop with the doors closed or a harness that has shorted, or another cause that prevents the fuel pump module from getting current.  The fuel pump is triggered at the PCM.  Keep in mind that the doors trigger the interior lighting.  Have any speakers or roof accessories been installed that would interfere with the interior light circuits or grounds?

To trace this further as an electrical/wiring issue, you need a factory wiring schematic to trace the fuel pump circuit and its relationship to the door wiring circuits.


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