99 XJ 4.0 Idles fine, accelerates fine under normal load, but I've been having hesitation issues at mid-throttle, worst at startup and gets better as the engine warms up. Backfires and chokes when I try to put any serious load on it at mid throttle. When I really gun it and the AW4 downshifts, I don't get the hesitation and the RPMs jump but it never shifts and it feels gutless like I'm running super lean. Changed the TPS, cleaned out the throttle body, and WHAM checked the pressure at the rail and it's 20-22psi. I used one of those gauges you rent from AutoZone for a $150 deposit. My question is, is this something I can do in the dark (have the thing packed up for a 400 mile one-way trip) and can I use the relief valve in the pressure tester to empty the tank, or is there an easy-ish way to empty the tank into a drip pan or something (not really concerned with keeping the gas, it's almost a year old) so that I can remove the skid and the fuel pump and swap them out. Also, could this be something simpler that's giving me 20-22 psi at the rail instead of the normal 49 (+/- 5psi)? Like a relay or something?

I also have a new crank sensor waiting in the wings in case that's the issue (I can always return it if I don't use it)

thanks in advance

 

Unless fuel is turned to a paste clogging lines or thier crimped . Nope seeing only item that could restrict pressure is fuel filter which is on pump also gotta take it out either way.

 

Gotta get a new fuel pump in there. Replace the entire "fuel pump assembly". Don't replace with an Airtex or anything rebranded unless you like doing things twice. Tank must come down, sorry to report.

You need 49 psi plus or minus 5 psi to run your 99 XJ fuel system.