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88 4.0 xj only stays started when holding key in start position

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Old 06-07-2012, 01:20 PM
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Default 88 4.0 xj only stays started when holding key in start position

Im having a probem starting my xj. It will start just fine but as soon as i let the key go after starting it, it shuts off. I can keep it runnning but i have to hold the key down. i read around on the forums and read that it might be the ballast resistor but i jumped it and it still wouldnt stay started. I really need to get this back on the road. thanks for any help!
Old 06-07-2012, 01:21 PM
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check cps
Old 06-07-2012, 01:30 PM
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I wouldn't worry about the CPS just yet. A working CPS is necessary for the motor to fire up, which yours is. It just won't stay running with the key released back to the "on" position.

You already bypassed the ballast resistor- check to see if there's voltage at both ends with the key on too.

Is there power to the coil with the key "on"?
Old 06-07-2012, 01:32 PM
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thanks for the quick responses. i just got a new cps from the dealer because i had the issue the other week. The cps is working fine. im going to check for readings now. Which wire should i check going to the coil?
Old 06-07-2012, 01:37 PM
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Originally Posted by bwis16
Im having a probem starting my xj. It will start just fine but as soon as i let the key go after starting it, it shuts off. I can keep it runnning but i have to hold the key down. i read around on the forums and read that it might be the ballast resistor but i jumped it and it still wouldnt stay started. I really need to get this back on the road. thanks for any help!
Mine did the same thing and it was the key switch, not where your key goes but the internal part.

Mine was sitting idling and the starter engaged all of the sudden, I shut it off and when I tried to restart it it would only stay running while holding the key switch in the start position.

The part was not too much, like $60 or something...

Here it is at Napa...Less than what I thought: http://www.napaonline.com/Catalog/Ca...557_0180985027
Old 06-07-2012, 01:37 PM
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When you release the key does the accesories also turn off or just the motor?

Sounds like bad ignition switch......
Old 06-07-2012, 01:45 PM
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Originally Posted by bwis16
thanks for the quick responses. i just got a new cps from the dealer because i had the issue the other week. The cps is working fine. im going to check for readings now. Which wire should i check going to the coil?

Well...you have an '88 which I'm not quite as familiar with. I think you have a control module wedded to the coil? There has to be a plug to the control module that powers the coil where you can test for voltage. Probably 3 wires- power, control signal and tach, IIRC. If there's no sign of +12V there, I'd work my way back to the ignition switch.
Old 06-07-2012, 01:47 PM
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Originally Posted by Radi
I wouldn't worry about the CPS just yet. A working CPS is necessary for the motor to fire up, which yours is. It just won't stay running with the key released back to the "on" position.

You already bypassed the ballast resistor- check to see if there's voltage at both ends with the key on too.

Is there power to the coil with the key "on"?

i got a reading of .03V DC from the wires off the ballast while the key was in the on position.
Old 06-07-2012, 01:49 PM
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Originally Posted by 93gc40
When you release the key does the accesories also turn off or just the motor?

Sounds like bad ignition switch......
the accesories stay on, just the motor turns off.

Is there any way to test the ignition starter switch before i put 40 bucks into it?
Old 06-07-2012, 01:55 PM
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im getting 12 volts to the coil with the key in the on position.

also, when i go to start it the accesories turn off then as i release the key and the engine shuts off the accesories turn back on.
Old 06-07-2012, 02:18 PM
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does anyone think it would have anything to do with fuel or the ground connections?

edit: i checked my fuel pressure and its from 35-39 psi
i bought and installed a new ignition starter switch (it wasnt bad only 13 bucks) and still does not start
i cleaned the ground connections by the oil dip stick

I am all out of ideas......its still doin the same thing. it starts up then immediatly shuts off unless i hold the key down. Im thinking vaccum leak but i dont know where to start

Last edited by bwis16; 06-07-2012 at 05:08 PM.
Old 06-07-2012, 07:31 PM
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bump
Old 06-07-2012, 08:11 PM
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ignition switch or fuel pump resistor main suspects here...
Old 06-07-2012, 08:19 PM
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i replaced the ignition switch. fuel pump resister? what is that, ive never heard of it.
Old 06-07-2012, 11:00 PM
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Fuel pump relay ! Very common to fail,it one of the 4 out by the battery


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