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No start 93 Cherokee help

R

redbirdrunner

NAXJA Forum User
Location
West Philly I A, Indiana
Alright guys my buddy just bought a 93 cherokee sport 4.0 aw4 np231. The guy he got it from said that it ran great but now for some reason now it will no start. We read through the no start xj troubleshooting guide and have searched my ass off. Things we have tried already include changing the CPS. No difference after that. We also changed the coil. If we put a voltmeter on the coil wire coming out going to the distributor it reads 9.76 volts, UNTIL you try to start it then it drops down to .3 I have no idea how this could be. We have cleaned and added grounds and no difference there either. If you unplug the 2 wire connector that goes into the coil you have 9.7 until you crank on it then it goes down to around 5 volts. All fuses and relays appear to be fine. We have racked our brains and cant think of anything else to try. THANKS
 
more importantl what is the voltage from the battery under a load make sure the battery is putting out no less than 10.5 volts under cranking conditions
 
redbirdrunner said:
I never checked the voltage at the battery butI would think it would be above 10.5 volts with the battery charger set to the high amp start setting( can't remember exactly how many amps).
Click to expand...

If the battery is bad you can hook a charger to it, but when a load is applied the voltage available to the vehicles electronics may be below 9 volts, and it simply isn't going to work under those conditions.
 
Well the battery was pulled out of his step dad's explorer that is daily driven and the charger was then put on because we had drained it some from cranking so much, the battery is still good because we put it right back in the explorer when we were done and he is still driving the explorer with that battery in it now.
 
Power for the coil comes from the ASD (Auto Shut Down) relay in the power distribution center (underhood fuse/relay box). Try swapping it out with another one if you have a spare or the A/C relay. Check the fuse for it (maybe # 20 a 30A fuse). The next thing I would look for are corroded (the insulation discolors and swells up if battery acid intrudes) or damaged wires. Are any wires melted on the exhaust manifold near the power steering pump?
 
All fuses tested good with the voltmeter and we swapped relays around every way you could think of, that yielded nothing. im thinking that there is a bare wire from the asd relay to the coil or from the ecm to the asd relay or maybe even a bad wire from the ecm to the crankshaft position sensor. Thoughts?
 
Reading through this thread again. Ok, you have no spark, right? Well, ECU/PCM-ASD relay-CPS/CKP-coil and their associated wiring. Seriously, pick one piece and test it and the associated harness.

BTW, have you done all of the grounds? Dipstick tube, back of head, etc.?
 
joe_peters said:
Reading through this thread again. Ok, you have no spark, right? Well, ECU/PCM-ASD relay-CPS/CKP-coil and their associated wiring. Seriously, pick one piece and test it and the associated harness.

BTW, have you done all of the grounds? Dipstick tube, back of head, etc.?
Click to expand...

I was just listing all the things that i need to check or re check. The coil has been changed and so has the cps/ckp, the wires are what I believe are now the problem. It isn't my jeep and the guy that owns it wanted to go the route of wasting money and throwing parts at it. Now that the easy things didn't work he needs to go with a more tedious approach of chasing wires down (at least I think anyway).
And yes all of the grounds have been taken off and cleaned up then put back on, we also added one from the head to the body and another one from the body to the battery.
 
Pull the ASD relay out and check for battery power at the pin 30 terminal. If it's not the same as the battery voltage you'll have to trace it back. You can also use a fused power wire from the battery to the relay output terminal to see if that works but only apply power when you are trying to start it, do not leave it connected. If you have good power in/out the the wire problem in on the output.

When I check fuses just to make sure I always pull them out and visually inspect each one. Don't overlook the possibility of missing fuses also.
 
Problem solved! Some how there was a slot for a mini fuse that we had overlooked, put a fuse in there and it fired right up, now on to the hole in the gas tank that the moron PO drilled in it to steal the gas out of it...
 
MJR said:
Missing fuse then? Seen that before, glad it's fixed.
Click to expand...

Yes, the first time I looked at the distribution box I thought that the spot didnt even have contacts for the fuse then I broke the test light back out and found there was power so I put a fuse in it and tested the power out of the coil while cranking and it hit hard enough to shut the meter down so i plugged it back in and it fired up after a little gas got poured down the throttle body.
 
redbirdrunner said:
Yes, the first time I looked at the distribution box I thought that the spot didnt even have contacts for the fuse then I broke the test light back out and found there was power so I put a fuse in it and tested the power out of the coil while cranking and it hit hard enough to shut the meter down so i plugged it back in and it fired up after a little gas got poured down the throttle body.
Click to expand...

Sweet!
 
redbirdrunner said:
Problem solved! Some how there was a slot for a mini fuse that we had overlooked, put a fuse in there and it fired right up, now on to the hole in the gas tank that the moron PO drilled in it to steal the gas out of it...
Click to expand...

...and that fuse was for the (insert appropriate circuit identification information here).

You have to share knowledge here.
 
joe_peters said:
...and that fuse was for the (insert appropriate circuit identification information here).

You have to share knowledge here.
Click to expand...

Well I would but my junk ass Chilton's manual didnt have a diagram of the power distribution box and the cover that is for it was gone already. Ill look at it again and try to explain it to you guys so you can tell me which fuse it is.
 
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