My 2000 6 cyl. fuel injected 4.0 Grand Cherokee ran perfect the night before, next morn, preparing for a trip to 6 flags with kids waiting, it would crank but not start, sprayed starter fluid into the butterfly when i turned it over it attempted to start so I'm getting spark. I turned it over while holding the needle open at the elector rail and a solid stream emitted so I'm getting fuel to the injector rail. Could it be that I'm not getting the Voltage pulse to my ejectors ? How do I test for this without a scope. Thanks for any info.
Dave

 

ECU is the source and you can get some 'noid lights to see if you aregetting the correct timing of the pulse.

 

Also, check out yur (CPS) Crank Position Sensor. That little jewel controls injector pulse and timing. Not sure about a GC but, on an XJ there is an electrical connector on the firewall between the motor and power brake booster. You can read it out with a simple multi-meter. The CPS is actually located on the upper driver's side of your bellhousing. It is a PITA to get to and change but, it can be done with simple hand tools and a little bit of patience.