Not too much pressure; but by adding the in-tank lift pump any leak that use to allow air to be sucked in, now will puke diesel fuel out that leak.
The plug-in for the fuel heater on the fuel filter head is a common problem and the factory actually issued a service bulletin about this problem.
The correct fix is to replace the fuel filter head with what is called a generation 2 filter head that has been redesigned to address the leaking plug connector.
But you really did the right thing by adding a in-tank lift pump! Now any leaks are self evident and easily found so they can be repaired...
And no more air in fuel worries and the Jeep will run and perform better by having the in-tank pump installed...
ps: lots of locations sell the second generation fuel head, just Google it!
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Supporting Vendor and Moderator of LOST05 Jeep Liberty CRD Limited
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount98 Dodge Cummins 24 Valve