99 jeep GCL v8 4.7L won't start but will crank. No CELs. There is one that pops on while trying to start but goes away after about 5 secs too quick to check. Just changed spark plugs last week. While trying to turn over there is a smell of gas but nothing leaking. Could really use some help with this thing please.

 

You are in the wrong forum. You have a Grand Cherokee and this forum is for regular Cherokee (XJ).

Post HERE in the GC forum. Good luck!

https://www.cherokeeforum.com/f5/

 

I moved the thread to the appropriate location. Thanks Tom.

 

You can use a scanner to check for pending codes, but I would suspect the cam sensor. If you've got fuel, that means the ASD relay is energized. This means you've got power to the ignition and injectors, BUT you're not getting spark. If the crank sensor is bad, you would only be able to crank it.

Just and opinion, mind you.

 

I had same problem, turned out my ignition coil plug wires were cracked so they kept arcing and blowing out IOD fuse. Check that first cause you don't want to mess with the crank sensor, that there is a S.O.B.

 

His 4.7 is coil-on-plug, but nice response. Oh...maybe you mean the primary wires.

 

Ok guys so sorry that it took me long to reply. I have a cheap scanner. Its a Bluetooth scanner I got off amazon. Theres no codes. I just replaced the crankposition sensor. Tried to start, it wanted to start but nothing. So I tested the spark plugs by grounding them to the chassis and the color is Orange. I test it on cylinder #3. I replaced cylinder #6 coil over due to it blowing out. I'm off tomorrow so ill be pulling all spark plugs and testing spark in all cylinders.

 

I think Dave said the CAM sensor, not the crank sensor. Which did you replace?

 

Crank I replaced it before he replied. And check all the spark plugs I've got 2-3 that are sparking blue and the rest are Orange

 

Ok just replaced the cam sensor and it fired up but then nothing. So close too... Ugh still no codes but I got my check gages light on

 

The way a spark coil works is they are supplied with 12 volts constantly and when required to fire, the PCM ungrounds them causing the magnetic field to collapse thus creating the high voltage spark. Your spark will be weak if a particular coil isn't getting a solid 12 volts or it's shorted internally. I'd check the primary wires for fraying or grounding out, particularly from corrosion in the connectors. Check the PCM cable connectors also. The check gauges light tells me the PCM isn't getting a full solid 12 volt supply. It operates on 5 volts controlled by an internal voltage control, but if it's not getting 12 volts, the control output will be low. The digital circuits won't function on less than 4 volts or they will sporadically.

One thing to keep in mind. The gauges are activated by information sent to them from the PCM, NOT directly from the sensors. Welcome to the digital age!

 

This isn't my area of expertise, but isn't there an issue with the PCM where either the wires need to be re-soldered or the 2 screws holding on, loosened?

 

Yeah, the solder connections from the circuit board to the terminal strip inside the PCM sometimes crack and need to be re-soldered. Some of them have case screws that are too long and short out. These problems are well known in ZJs but that doesn't mean your WJ doesn't have the same problem. The solder cracking started when they stopped using leaded solder. The lead free stuff is brittle and vibration tends to crack the connections. The best solder to use for the repair is solid core leaded electronic stuff if you can find it.

 

Thanks I'll go check that when I get the chance. This problem all started when I changed the spark plugs. You think I should replace some of the coil plugs?