The Cherokee WK2 platform has a fairly shallow, dual sump tank, and a problem with the transfer system will immediate lead to a fuel pressure/delivery/starvation issue. At any rate, due to the shallow design of the fuel tank, it is imperative that the operator keep more fuel than normal at all times.
A fuel pressure issue may cause a starvation issue, as the system needs to be running and generating at least 25-30 psi to transfer fuel to the driver side. Also, if the driver side is starved of fuel, you will have fuel pressure issues. Of course, in the process of diagnosis, the overall fuel system health should also be considered. (i.e. fuel pumps, filters, electrical connections, etc.)
If the fuel system is healthy and creating good fuel pressure, but NOT transferring fuel, then you likely have a clogged venturi jet and/or an improperly connected in-tank connector. Be advised, the transfer only works when the fuel pump is running and the system is under pressure. So, if you are trying to drain fuel with the feed line connected, it will NOT transfer fuel.
We've seen some cases where installation of the pump module was attempted without disconnecting the flange from the lower assembly, which makes it very likely that the large quick disconnect inside the tank doesn't fully engaged, and will cause the transfer to fail. (there are four screws on the top of the pump assembly...please see attached pic)
If the venturi jet is plugged, you can use a 0.025" drill to chase the venturi jet BY HAND (not in a drill) to make sure it is clear. See attached a pic with the venturi jet circled in yellow.
We would like to emphasize that diagnosis of this type of problem should only be attempted at a professional shop with the proper tools and and equipment to deal with fuel, fuel vapors, and the associated health and fire hazards.
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