Jeep Cherokee 1999 Electronic Service Manual page 1197

14 - 6 FUEL SYSTEM
DESCRI PT I ON AN D OPERAT I ON (Cont inue d)
Fig. 5 Fuel Rail/Fuel Damper—2.5L Engine
Th e fu el r a il is n ot r epa ir a ble.
Fig. 6 Fuel Rail—4.0L Engine
FUEL TANK FILLER TUBE CAP
Th e loss of a n y fu el or va por ou t of filler n eck is
pr even t ed by t h e u se of a pr essu r e-va cu u m fu el t a n k
filler t u be ca p. Relief va lves in side t h e ca p will
r elea se fu el t a n k pr essu r e a t pr edet er m in ed pr es-
su r es. F u el t a n k va cu u m will a lso be r elea sed a t pr e-
det er m in ed va lu es. Th is ca p m u st be r epla ced by a
sim ila r u n it if r epla cem en t is n ecessa r y. Th is is in
or der for t h e syst em t o r em a in effect ive.
CAUTION: Remove fuel tank filler tube cap before
servicing any fuel system component. This is done
to help relieve tank pressure. If equipped with a
California emissions package and a Leak Detection
Pump (LDP), the secondary seal below the fill cap
must be pressed (opened) to relieve fuel tank pres-
sure.
QUICK-CONNECT FITTINGS
Differ en t t ypes of qu ick-con n ect fit t in gs a r e u sed t o
a t t a ch va r iou s fu el syst em com pon en t s. Th ese a r e: a
sin gle-t a b t ype, a t wo-t a b t ype or a pla st ic r et a in er
r in g t ype. Som e a r e equ ipped wit h sa fet y la t ch clips.
Refer t o t h e Rem ova l/In st a lla t ion sect ion for m or e
in for m a t ion .
CAUTION: The interior components (o-rings, spac-
ers) of quick-connect fitting are not serviced sepa-
rately, but new pull tabs are available for some
types. Do not attempt to repair damaged fittings or
fuel lines/tubes. If repair is necessary, replace the
complete fuel tube assembly.
DI AGN OSI S AN D T EST I N G
FUEL PUMP PRESSURE TEST—ALL ENGINES
WITH PRESSURE TEST PORT
Use t h is t est in con ju n ct ion wit h t h e F u el P u m p
Ca pa cit y Test , F u el P r essu r e Lea k Down Test a n d
F u el P u m p Am per a ge Test fou n d elsewh er e in t h is
gr ou p.
Ch e c k Va lv e Op e ra tio n : Th e elect r ic fu el pu m p
ou t let con t a in s a on e-wa y ch eck va lve t o pr even t fu el
flow ba ck in t o t h e t a n k a n d t o m a in t a in fu el su pply
lin e pr essu r e (en gin e wa r m ) wh en pu m p is n ot oper-
a t ion a l. It is a lso u sed t o keep t h e fu el su pply lin e
fu ll of ga solin e wh en pu m p is n ot oper a t ion a l. Aft er
t h e veh icle h a s cooled down , fu el pr essu r e m a y dr op
t o 0 psi (cold flu id con t r a ct s), bu t liqu id ga solin e will
r em a in in fu el su pply lin e bet ween t h e ch eck va lve
a n d fu el in ject or s.
d ro p p e d to 0 p s i o n a c o o le d d o w n v e h ic le
(e n g in e o ff) is a n o rm a l c o n d itio n . Wh en t h e elec-
t r ic fu el pu m p is a ct iva t ed, fu el pr essu r e sh ou ld
im m e d ia te ly (1–2 secon ds) r ise t o specifica t ion .
All fu el syst em s a r e equ ipped wit h a fu el t a n k
m odu le m ou n t ed, com bin a t ion fu el filt er /fu el pr essu r e
r egu la t or. Th e fu el pr essu r e r egu la t or is n ot con -
t r olled by en gin e va cu u m .
WARNING: THE FUEL SYSTEM IS UNDER CON-
STANT FUEL PRESSURE EVEN WITH THE ENGINE
OFF. BEFORE DISCONNECTING FUEL LINE AT
FUEL RAIL, THIS PRESSURE MUST BE RELEASED.
REFER TO THE
RELEASE PROCEDURE.
(1) Rem ove pr ot ect ive ca p a t fu el r a il t est por t .
Con n ect t h e 0–414 kP a (0-60 psi) fu el pr essu r e ga u ge
F u e l p re s s u re th a t
FUEL SYSTEM PRESSURE
X J
h a s