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Unread 10-05-2013, 12:54 AM   #1
grussell
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2001 WJ 
 
Join Date: May 2013
Location: Longmont, CO
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Engine cranks will not start. What I have checked-NOW RUNNING-

I currently have no fuel pressure at the rail.

I have spark because i can spray starter fluid into the intake and the engine will start.

I do not have power at the fuel pump fuse.
I have power at the fuel pump relay.
Jumping the pins in the relay connector does not prime the fuel pump.
I have power at the fuel pump connector above the axel.
I could not hear the fuel pump prime when the key was turned to on so I dropped the fule tank today and hot wired the fuel pump and it ran and spit out gas.
I thought it might be the fuel pump, but now im thinking it is the PCM. I had issues with the engine dying and not starting for 5-10 minutes so I replaced the CPS and it ran great for a day. I started it first thing this morning and moved it into the driveway and 1 hour later it would not start and did not start trying it several times during the day. The engine dying was at random times and different ambient teperatures.

Anyway to diagnose the PCM?

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Unread 10-05-2013, 01:16 AM   #2
Cadoc08
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Don't take this the wrong way, but are you sure you're looking at the right fuse? If you don't have power at the fuse for the control side of the relay then you shouldn't have power at the connector at the axle because the relay won't be actuated. If you had the means to have the PCM scanned for codes that would be helpful. When you replaced the CPS did you check for possible metal fatigue on the pigtail that goes to it? An intermittent open at that harness could explain why it worked for awhile and then stopped. Contrary to popular belief the computer is almost never the problem. I would advise going through every measure you can before considering a new PCM. What was your voltage at the connector above the axle?
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Unread 10-05-2013, 09:01 AM   #3
grussell
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I checked power at the 10amp fuse in the fuse box under the hood. I will check the voltage at the fuse and the connection again today and post. The harness around the back of the valve cover looks good and is still attached to the mount on the valve cover bolt. It doesnt look like it could be rubbing.
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Unread 10-05-2013, 09:04 AM   #4
wsar10
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A non-MOPAR crank sensor could be your issue or mis-alignment of the sensor. Same as above if there is no power at the fuse the relay would dead.

pull codes with the key trick:
on-off-on-off-on look at odometer
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QUOTE=billzcat1;wsar10 is right on point on this oil thread - as usual. Anyone reading this would be well-served taking his advice.


-03 WJ laredo 4.0 120k a few minor mods
-93 XJ 5spd, 3" zone lift
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Unread 10-05-2013, 10:26 AM   #5
grussell
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Okay, I checked the voltage again.

I have voltage at the rear tank connector for the fuel sending unit, but not the fuel pump. I can get 11.97 volts on one side of the fuel pump fuse but I can not continuity on the other side. The only codes ar P1282 and P0463, but I have the fuel pump connector unplugged because the fuel tank is out. Should I be able to get continuity on the ground side of the fuse connector?
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Unread 10-05-2013, 11:21 AM   #6
wsar10
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there is no polarity on a fuse..... its an inline thing.
if you do not have continuity across the fuse than it is shot. The question is WHY ??
Fuses blow for a reason, otherwise you had a"hi-draw" situation because of XXXXX.
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QUOTE=billzcat1;wsar10 is right on point on this oil thread - as usual. Anyone reading this would be well-served taking his advice.


-03 WJ laredo 4.0 120k a few minor mods
-93 XJ 5spd, 3" zone lift
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Unread 10-05-2013, 11:26 AM   #7
grussell
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Hmm, thats right on the fuse. One side is hot the other is not, that may be my problem. I will trace the wiring on that side and see what I come up with.

A side note- when I was checking the fuses under the dash I noticed F32 and F33 do not have fuses in them, but both slots have power.

F32-Ignition Run/Start-Airbag
F33-Ingnition Run/Only-Airbag

What are these for?
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Unread 10-05-2013, 11:51 AM   #8
wsar10
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after looking at my FSM there are 2 fuses associated with fuel pump, one is on the coil side of the relay the other is the switched side of the relay, the coil side fuse is #12 (10A) in the "junction block" the other #24 (20A) in the "power distribution center".
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QUOTE=billzcat1;wsar10 is right on point on this oil thread - as usual. Anyone reading this would be well-served taking his advice.


-03 WJ laredo 4.0 120k a few minor mods
-93 XJ 5spd, 3" zone lift
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Unread 10-05-2013, 05:46 PM   #9
grussell
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Okay she is all back together and I have driven her 3 separate times with no issues. Question, I took the lower trim panel off under the sterring wheel to get better access to the fuse block and found a cable running from the consule into the ignition switch unplugged. It has a yellow plastic housing with a spring loaded plunger. I snapped it back into the ignition switch and after checking all of the pertinent fuses and plugs put it all back together. She is now running. Is the cable part of the ignition system to prevent starting unless in Park or Neutral?
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Unread 10-06-2013, 06:07 PM   #10
grussell
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I believe she is fixed I replaced the fuel pump this afternoon and presto! We shall see tomorrow.
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