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View Full Version : '91 XJ Engine No Start- Voltage drop at coil


mahanja
April 7th, 2008, 22:03
I have a '91 XJ with a 4.0L and AW4. I just completed rebuilding both and am having spark issues. The spark issues are that it has none. I have traced the power issue to the coil. It has 12v coming into the coil and approx. 5.5v coming out with the key in the on position. The voltage completely drops when the engine is cranked. I initially thought it was the coil but after changing out 3 I had handy including a known good, I have looked elsewhere. I checked the codes and it pops a code for the TPS and Distributor Stator. The TPS reads good as per the Service Manual as does the Distributor Stator. Could either of these cause the voltage drop in the coil? I tested the Distributor Stator but only had a digital multimeter so it reads that it maintains 5v continously during cranking. I am a bit leary about throwing a $35 part at the problem when it worked fine when it came out. Could something else be making it read incorrectly? I am going to use a analog multimeter when I get home from work tonight.

Also, I know that the CPS in Jeeps go bad all the time but I installed a new one to no avail.

As far as the rest of the motor goes, I have good fuel pressure and the plugs get a fuel residue after cranking so I know the fuel is good. I also held the throttle body open as to ensure that the engine has enough air. Everything else seems to be working well. This model has the factory alarm system and the Service Manual says that it should be disabled by using the remote to reset (unlock the doors) the system upon reconnecting the battery. It has been done exactly as the manual states.

Any help is greatly appreciated!

mahanja
April 10th, 2008, 00:08
Ok. Since everyone hasn't helped at all, maybe I can leave some insight for someone who finds this thread. I ended up tracing my problem to a broken wire that runs between the distributor stator, the CPS, and pin 7 of the ECU. It was broken all the way up by the bulkhead behind the valve cover. The orange wire at the three can be probed and checked for continuity.

DonnMcc
December 29th, 2008, 06:42
were you getting fuel also?I've got me some problems with mine.