Jeep just shut off

RenegadeT

RenegadeT

no shirt,no shoes,no dice
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Mar 24, 2005
Location
Stokesdale-Greensboro
'99 XJ 4.0L/AW4 140kmile on it, driving home steady at 60MPH, and all of a sudden it just shuts off. No sputtering like lack of fuel, gauge shows half tank, and that seems correct as I filled it earlier in the week. All electrical seems fine, it cranks strong, radio, windows, etc. work fine. Pressed the schrader valve on the fuel rail it had some pressure. Fiddled with the CPS connector, pulled the coil wire, didnt have any spark while cranking. Swapped the fuel pump and starter relay, no change. I am not hearing the fuel pump buzz when I turn the key on. That is the extent of our (madmonk...thanks for pulling over to help) diagnosis. I caught a ride home, grabbed the trailer and brought it home, more tommorrow.
I was thinking...
1- CPS
2- coil
3- fuel pump
anything else? what should I be checking? I have a volmeter and I think a fuel pressure gauge, and I sort of know how to use them :lol:
 
cps
 
I've swapped out the CPS before in a previous XJ, so I know how much it sucks to get to. Is there any way to check it before I pull it? Bigwoody says a good one will show AC voltage while cranking. Mine (all?) has a 3-pin connector, what should I check?
 
Check to see if you've got spark. If so, fuel pump. My money is on the coil too though. When they go you get no warning. Would it not keep running at all with a bad CPS and just not restart?
 
Tony, do this-
Check for loss of spark or fuel. Most likely will be loss of spark. If there is no spark, unplug the coil. Insert a paper clip or some sort of jumper between the 2 pins. Run a test light from that jumper to the positive post of the battery. Crank engine. If it flashes, the coil is bad. If it doesn't flash, the signal circuit for crankshaft position is bad. Which means crank sensor or pcm. Literally, 99.9% of the time, it'll be the crank sensor.
 
thanks guys. This morning I did hear the fuel pump humming, nos start still. I unplugged the CPS...no CEL. A new CPS from Advance, all is good.
 
typically if the cps goes out the guages for volts, fuel level and temperature will be flat. with the ignition on.. unplug the cps and the guages should return to normal
 
gt500swim said:
typically if the cps goes out the guages for volts, fuel level and temperature will be flat. with the ignition on.. unplug the cps and the guages should return to normal
Click to expand...

Only if it shorts when it goes. If it fails open, it will simply not start.
Just and FYI.
 
it must have failed open, all gauges were working fine with and without the CPS pluggin in, and no CEL light. Everything seemed to be working as normal, except that it wouldnt fire when cranked.
I checked continutity between the old CPS and new...they were different. Besides the fact that 99.9% of the people I asked said that 99.9% of the time its the crank sensor, this made me even more confident to go ahead and swap it out.
 
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