Why won't it FIRE!!!!!!

GreenReaper93

New member
Hey everyone! It's been awhile since I've been on... busy as you wouldn't believe (I'll explain later if anyone cares). Anyway, I'm having issues with the ignition system. Here's the rundown: 1999 Cherokee Sport, I-6 motor, AT.

I was driving back to the office from a delivery when I started to feel a loss of momentum. I quickly looked down at my gauges and for a moment they were still reading normal. I couple of seconds later they all dropped. I coasted to a stop on the side of the road and turned off the ignition. I waited for a second or two and tried to turn the key over. Nothing. Not a single guage moved - Volts didn't show, Temp didn't move from 0, and the gas was sitting at E.

I had it towed home and started looking through the engine compartment and found that the idiots before me spliced the Green/Orange wire that runs to the coil, alternator and fuel injectors to the battery. I replaced the brain (used) and fixed the issue with the guages, but the Jeep still won't fire.

I next hooked up my inline spark check tool from the coil to the center of the distributor cap and cranked the engine. Once more, nothing. I bought a new coil, but before installing it I checked the old one with an ohm-meter and followed the instructions in my Haynes manual. BOTH coils tested the same. Here's where I would like some advice....

Since both coils tested the same, that leads me to believe that 1) my original coil is fine, or 2) both coils are bad. My question is the pick-up coil in the distributor the cause for my ignition coil not firing? Is there an inline fuse on that particulare wire that I just can't find?

Oh, when I hooked up my multimeter to one of the connectors and cranked the engine, it read 0.5 volts coming from the computer to the ignition coil - is that right???? Thanks so much everyone!

GR93
 

Same thing happened on my 97 xj, it was the CPS. The gauges were exactly as you said. The fuel pump did come on however. Also, the engine turned over but wouldn't fire.
 
Ok, here's an update from today. I replaced the CPS (the wires on the old unit looked like they were melted - I'm guessing it was from touching the exhaust). I connected everything back up and tried to start it again... still nothing. I checked the voltage going to the coil once again - reading 0.50 volts. I'm still thinking that's too low. I re-connected my inline spark tester from the coil tip to the center of the distributor cap and still didn't get a light.

Does anyone know if there's an inline fuse on the wire going to the coil? Did that fried CPS tweak something else?

Any light that can be shed on this would be much appreciated!!! Thanks!
 

cj radiator

Did you check the fuses in the panel under the hood yet? start with the obvious.
 
My roomie had a wire harness melt to the exhaust, not sure which one it was, but it blew one of the maxi-fuses under the hood in his '95 XJ, the Check Engine light was constantly on, gauges were all effed up, and it just cranked and cranked and cranked, but wouldn't fire, ended up being that fuse, and of course, the wire harness...
 

Re: RE: Re: RE: Re: RE: Jeepy!!!

Hi,

GreenReaper93 said:
I checked the voltage going to the coil once again - reading 0.50 volts. I'm still thinking that's too low.

Are you trying to read the voltage in the wire going directly from the computer to the ignition module? If so, realize that this is a pulsed DC signal, and you can NOT measure it correctly with a DC voltmeter or multimeter set to DC volts. If you want, you could try setting the multimeter to AC volts, but even then it probably wouldn't pickup the signal correctly. That's okay, because all you really need to know is whether there is power present or not on that line. A better way to test this might be to connect an LED and series resistor combonation from that wire to ground and see if the LED lights or not. But do **NOT** use an incandescent lamp to do this test, as the high power draw of such a lamp could damage the computer's output circuitry.

If you need an example of an LED + series resistor circuit, let me know...

Hope that helps,
-Nick :!:
 
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