My 2001 jeep grand Cherokee larado L6 4.0 I have a crank/no start condition I got spark and fuel pump is coming on/
the pump can make noise, good or bad.
its just a simple dc motor rotor pump.
this jeep is EFI so pressure matters not sounds.
if the pump sounds dead that is dead pump or no 12vdc power to it, voltmeter wins this battle.
why not learn first that nostarts have 50 causes.
one can guess
one can replace parts in statistical order (sorry your car never reads stats)
or one can learn to diagnose EFI. i cant teach you in this box.
but I can put you on the correct track for sure.
1: lets pretend the ENGINE is ok , the larger list of parts bad.
2: and go for SPARK. no gas engine runs with no spark so
is like NUMBER ONE first test
GOT SPARK , my guess is you dont even know what that means.
google or youtube how to test spark, 10,000 examples for 100 years running. (car repair for dummies in the book store "?)
3: spark needs to be good on all 5 cylinders. not 1.
so most fail to do that, lazy or ? i dont know why.
this engine and this year runs a odd huge single coil rail pack
so not scanning the PCM now ,is really making the job hard.
to do this correctly lacking most tools. (scanner missing)
the FSM tells you how. its free to read, why not read that now
in the offical jeep book.
what is done is the pack is racked back(unbolted )
and test spark plugs used.
if you know EFI, you know 2 things, in same book
do not short plugs. nor run them open circuited , on purpose.
so getting 6 plugs there and 6 grounds, is a daunting task.
for most persons, (not the shop its normal)
chapter 8I (8 india) in the FSM is SPARK chapter, read it now.
if the spark test passes then test fuel, test passes.
instant start spray in a can, buy it in any auto store earth.
if that works engines sounds great. then
we ATTACK fuel now.
next is fuel pressure,
just because a rail fitting shows leaks fuel test.
means nothing , it only means the pump is not 100% dead
EFI need spec pressure to run any engine,
case in point, 10 PSI the engine can not run.
the running fuel pressure is
49.2 psi 6 5 psi). not 10.
over 55.4psi is bad FPR
the books says, below 44.2 psi (weak pump or FPR bad)
there you go, all way to find this, (engine good)
Mr, otto cycle engines, same deal for 100 years
engine good. CAT convertor not melted.
good spark x6 (this case)
and proper fueling , not starving not flood , it starts.
THE PCM does FUEL and SPARK now from 1988 to now.
Jan 20, 2017 |
Jeep Cars & Trucks