ChadMagruderhasaJeep

This is a long story...
To start, my wife complained of the Jeep losing power on acceleration and taking a long time to start. When I looked at it would not start at all, just crank.
2004 Jeep Grand Cherokee 4.0L I6 - stock
Have spark
Have compression
Have fuel pressure
Initially got code relating to Crankshaft position sensor
Started with starter fluid in intake

New crankshaft position sensor
New camshaft position sensor
New spark plugs
New battery
New fuel filter
New fuel pump
New battery terminals

Fuses and relays in PDC good
Throttle position sensor good
Checked and cleaned grounds in engine compartment, all good

Fuel injectors resistance within range
Checked spray with 9V battery at terminals, all good
Noticed no supply voltage to any fuel injector with key on
Injector pulse with key on at all 6
No voltage across either side fuse 26, fuse good
No load voltage from ASD Relay to fuse 26, relay good
ASD load supply 12v
ASD control 12v with key on
Used jumper wire to bypass relay at load terminals (30 & 87), voltage across fuse 26, voltage at injectors, voltage at TCM relay and fuse
Tested ASD relay control wires (85 & 86) from PDC to connectors and PCM, no opens or shorts

ASD relay control will not ground to energize the coil

Tried starting it with jumper wires connecting ASD load terminals
Key on, lights and accessories work, fuel pump primed
Key start, all goes dark...

Disconnect and reconnect battery, lights and accessories work again until key start... then everything shuts down immediately and won't work again until I disconnect the battery for awhile.
Tested for parasitic drain, read 250mA of current.
Disconnected every fuse in PDC and junction box one at a time, only one to make any difference was the IOD fuse

One thing I noticed was that with the key in the ignition it beeped like the driver's door was open, checked wires in the door and the thick black one (ground?) was broken apart. Not sure if this has anything to do with my parasitic drain or starting issue or if it is just coincidence.

I have no clue as to what could cause this electrical problem or where to start to diagnose and fix, please help! I've been pouring over electrical wiring diagrams all day and am no closer to figuring out what the hell is wrong with my jeep... should I be looking at the ignition switch or maybe a fried PCM???

Thanks in advance for any advice!
-Chad

dave1123

Clue; Most of the devises controlled by the PCM are supplied with 12v with the key on but are grounded thru drivers in the PCM to function. The ASD relay won't come in until the PCM gets a CPS signal. It controls the ignition and fuel injector circuits. The PCM will protect itself by shutting down if there is a problem, like your jumper on the ASD.

I originally was going to say plugged converter.

ChadMagruderhasaJeep

Thanks,
I will check on that again and make sure the CPS has voltage/ground and verify the signal.

I went out again tonight and messed with it. Put key to on and removed the positive battery cable. When I reconnected it I checked the load line of the ASD and the injector voltage, the supply comes on for two seconds then shuts off like normal so the PCM is grounding the relay.
Also, if I try to start the jeep from the key on position everything goes dead and I have to reset the battery connection, but if I start from the key off position it cranks...

If the CPS is not sending the correct signal to the PCM, could this explain the ignition switch thing?

dave1123

No CPS signal shouldn't effect cranking. That ignition switch thing has me stumped.

ChadMagruderhasaJeep

I figured out the ignition thing, kinda... took off the control wire to starter solenoid from P/N safety switch to test voltage from ignition through the switch, worked fine and with it disconnected nothing when dead on start. The heavy gauge wire from the solenoid to the motor had corrosion on it and motor would not activate with screwdriver jumping battery source, took it off and cleaned everything, tested, and reinstalled. Now the jeep cranks again no problem, but still does not start. I'm going to start over and re-check fuel, air, and spark... checked for any codes and only came up with P1490 and P1489.

*Edit
The starter is not working again. My new theory is that the starter is drawing too much current to turn the engine and not enough is left over to power the injectors, misleading me to think it is a fuel problem. New brushes to rebuild the starter cost about the same as pulling one from the scrapyard, so tomorrow I will put another starter on and see if the jeep fires up.

ChadMagruderhasaJeep

New starter motor, cranks great now... still will not start without starter fluid.
I took apart the fuel rail, cleaned and tested injectors. all good and spray plenty of fuel.
All 6 have 12v source and ground pulse from PCM
Tested for spark again, good spark on all 6
All the sensors are getting voltage and ground and are working fine
All the grounds are clean and are making good connections.

Tomorrow I'm going to take off the catalytic converter to make sure it is not plugged, might just buy a new one anyways and weld it on. Also going to test the gas for contaminates in case some F***er hates me.
Going to do an oil change too, noticed it was low and could use one.
I'm running out of ideas here... Anyone know what else could be happening with the fuel system?

On the plus side I did find a sweet deal on new rims and tires, so there is that to look forward to...

Hotroddinlogan

It could be an o2 sensor or a MAP sensor

BlueRidgeMark

It's a 4 year old thread.



Here is where to find the date of a post.

jpcallan

At the risk of this sounding like a primitive suggestion, but your symptom sound a lot like a big vacuum leak, given it fires up on starting fluid.
Maybe a loose or split hose is to blame? The Idle Air Control Valve creates a controlled vacuum leak, so a stuck open IACV will mimic these symptoms.

OTC Tools makes a smoke generator called the 6522 LeakTamer that creats mineral oil fog. I saw a YouTube video where a mechanic used it to ferret out a difficult to locate intake manifold vacuum leak. There are other vacuum leak locating techniques as well.