[jimbo141]

The wifes 2004 grand cherokee laredo 4.0 died on the way home today... And of coarse i am out of town. She said while driving it just shut off and she coasted to the curb. It cranks over great but wont start. Any suggestions on what i should start checking when i get home in the morning? It was running great up to this point.

[zvanit03ru]

Crankshaft position sensor? A common fail point, frequently without warning. Been there; done that..

[jimbo141]

Will cranshaft position sensor throw a code? I have a OD scan tool that i can hook up when i get home.

[xJoshxx]

Fuel pump. this has happen to me twice.

take the cap of the valve on the fuel rail turn the key press it in or hook a fuel pressure gauge up to it.

also listen for the pump to prime up. but turning pressing int he shrader valve ( tire valve looking thing) you should get STEADY stream of gas if the pump is working.

Ok so TURN key to ON

pop hood

Unscrew black tire cap looking thing Attach either a fuel pressure gauge to it. or press the valve in mine gave a great squirt then it just trickled out after that i believe fuel psi should be 40 when just primed and 40-45 when running.

[jeepster425]

is it out of fuel?

[classicmetalman]

Originally Posted by zvanit03ru

Crankshaft position sensor? A common fail point, frequently without warning. Been there; done that..

X2 - Had the same symptoms, be running fine then just die like someone turned the key and shut it off. Would crank over real strong but no start. Changed the Crank sensor with a dealer replacement and all is good again, got my fingers crossed ofcourse.

[jimbo141]

No pressure at fuel rail (not a drop) But he said you can hear the pump running at the tank.... my son said its throwing a P1389 code

[jimbo141]

yes definately has fuel

[classicmetalman]

Originally Posted by meat27

Just found the problem.

I had seen other people swapping the relays, so I did that, still had problem, and jumped on here.

Then took another look and found and ASD 30A fuse blown. Swapped it and runs good. Duh. Sorry I jumped on here without going through the fuses first.

Thanks for the advice Joe

Relay or Fuse??

[xJoshxx]

Originally Posted by jimbo141

No pressure at fuel rail (not a drop) But he said you can hear the pump running at the tank.... my son said its throwing a P1389 code

No ASD Relay Output Voltage At PCM


No Z1 or Z2 voltage sensed when the auto shutdown relay is energized.

Get a new ASD relay and check the ASD fuse.



Fuse #12

[jimbo141]

ok we narrowed it down i got fuel but my 15 amp injector (#26) fuse keeps blowing everytime i turn the key it runs for a bit and then blows.... uh oh this aint good

[jimbo141]

anybody? jeep is currently parked on side of road

[jimbo141]

had it running for an hour and it was fine. Then took it out later and hit some big bumps and the fuel injector fuse near battery keeps blowing. Obviously it's a dead short.... Any ideas of where to start looking for shorts?

[jimbo141]

A HA Got ya's all stumped..... Well dont feel bad i am too !!!

[TroyJollimore]

Some people may say to just use a bigger fuse... I'm not a Jeep guy, but I know my way around cars and troubleshooting. This would be easier if you had a wiring diagram or schematic out of a service manual. Otherwise, since it's JUST the injector fuse, I'd start either at that fuse and work your way towards the injectors, or the other way around. Tracing electrical faults are a PAIN.

Take a general look around your engine bay and battery area. Make sure any obvious grounding spots are taken care of. I'm not familiar with the GC, any bad spots for wires wearing through under the interior carpets or panels?