post symptoms and not hunts, hunts are zero fun.
there is no such thing (switch)
no engine told, no country. USA answers only.
4.0-L or 4.7L?
I guess engine not told is dead.
now the rules for fuel.
all fuses GOOD and tank has clean fuel,.
- if spark dies, PCM shuts off fuel for no crash and burn fires.
- the air bags (SRS) sensors activated and the PCU sees that and cuts fuel. so far 2 things normal.(fuel)
- fuel pump relay dead. (bad or PCM did it)fuel pump fuse blown?
- FPR stuck open and fuel pressure near zero, oops wont run.
- fuel pump dead (cranking) but not if 12vdc not making it to pump.
- some PCM cut spark and fuel if oil pressure is 0 zero.
- some owners add this phantom switch, see it but I can inspect the fuel lines front to end in 15min work to see IT'S NOT THERE. eyeballs only checked.
so dead engine?
check for spark first not fuel first, do not buy parts guessing.
spark must be tested, at all spark plugs not just 1.
if all are dead , CMP sensor may be dead. or CKP
both engines are chain drive cam, 4.7L is SOHC head chains
and the chains can go 250,000 miles easy (clean oil)
no miles told no chain noise told
if spark works , test fuel runs the engine (spray starting fuel)
if not check engine compression
fuel is last.
takes a good engine + spark to burn fuel.(gasoline ,not CRD jeeps)
I have 3.7L smaller version in ,my WK jeep. 4.7l too has 3 chains
if all is good., we check fuel pressure at the rail with a guage
and spec is.
(
49.2 psi +/- 5 psi) WJ jeep it is. 2000.
the FPR regulates this pressure for sure cranking a dead engine
not at KEYON< but cranked or running, pressures.
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