No start after battery disconnect

[Chrisricks6]

I flat tow my 1999 4.0 to and from work, and like everything recommends, i disconnect the battery when doing so. Usually I get the normal rough idle for 10 minutes or so afterwards, a couple of times I've had issues with it reading the chip in my key, but after a few tries it comes to life, this time I have nothing, turns over fine but won't start. Seems like the pcm has been whipped clean or something. I haven't had time to check things with a voltmeter, but I did try to jump it off upon arrival in case voltage was low, and trickle charged it all night and the battery is holding a good charge (optima yellowtop) the fuel pump isn't priming or anything on it, and it was running fine when I hooked it up to tow. I won't ever disconnect the battery again, I'll just hook it up with a charge wire, but any help getting it running again would be greatly appreciated.

 

[Pascal25]

Do your gauges or dash show anything when you are trying to start it?

 

[Gilaguy23]

Who says unhook the battery to flat tow?? Never heard that one or why??, In a nut shell your are deleting the adaptive memory in the ecm when unhooking the battery.

 

[Chrisricks6]

Who says unhook the battery to flat tow?? Never heard that one or why??, In a nut shell your are deleting the adaptive memory in the ecm when unhooking the battery.

From what I've been told with the battery hooked up it will register miles when being flat towed with the key on, plus my stereo would drain it anyway, it's a 7 or 8 hour trip and I can't actually turn my stereo off with the key on, can only turn the screen off

 

[Chrisricks6]

Who says unhook the battery to flat tow?? Never heard that one or why??, In a nut shell your are deleting the adaptive memory in the ecm when unhooking the battery.

Do your gauges or dash show anything when you are trying to start it?

Honesty I'm not sure, I guess I've never looked at the gauge until after it starts to know what they normally do on startup. About all I had time to do was hook the fuel pressure gauge up because I normally hear the fuel pump prime and didn't, but it was noisy outside. I will check it tomorrow and get back with you, thanks

 

[macleanflood]

Check fuel pressure and spray some starting fluid in the throttle body.

-Mac

 

[B1Toad]

From what I've been told with the battery hooked up it will register miles when being flat towed with the key on, plus my stereo would drain it anyway, it's a 7 or 8 hour trip and I can't actually turn my stereo off with the key on, can only turn the screen off

Why are you turning the key to on? The first click unlocks the steering wheel. It's lock>unlock>run>crank. Or just remove the locking cam which is a 30 minute job so you can tow without the key being in your Jeep at all.

 

[DaveC]

As B1Toad said, just unlock the steering wheel by turning to the first position and leave the battery connected. I flat tow mine a few times this way every year and no mileage is clocked and no power drained. Don't have the TJ and owner's manual with me at the moment, but I'm pretty sure there's no mention of disconnecting the battery when flat towing.

 

[Chrisricks6]

Why are you turning the key to on? The first click unlocks the steering wheel. It's lock>unlock>run>crank. Or just remove the locking cam which is a 30 minute job so you can tow without the key being in your Jeep at all.

I'll try that, I don't want to remove the lock cam, I use it at theboat ramp, it's a standard, and I never have been able to get the parking brake to hold worth a damn lol, put black magic brakes on it front and rear, took it to 2 different brake shops, still have about 3 days of parking/rear brakes and then they back off, I've given up on that, but that's for another thread

 

[Chrisricks6]

Why are you turning the key to on? The first click unlocks the steering wheel. It's lock>unlock>run>crank. Or just remove the locking cam which is a 30 minute job so you can tow without the key being in your Jeep at all.

I'll try that, I don't want to remove the lock cam, I use it at theboat ramp, it's a standard, and I never have been able to get the parking brake to hold worth a damn lol, put black magic brakes on it front and rear, took it to 2 different brake shops, still have about 3 days of parking/rear brakes and then they back off, I've given up on that, but that's for another thread

Do your gauges or dash show anything when you are trying to start it?

Honesty I'm not sure, I guess I've never looked at the gauge until after it starts to know what they normally do on startup. About all I had time to do was hook the fuel pressure gauge up because I normally hear the fuel pump prime and didn't, but it was noisy outside. I will check it tomorrow and get back with you, thanks

Sorry for the late reply, I'm on a site with no cell coverageand can only check stuff when I come into town, I did check earlier and I have nothing at the gauges, the gauges light up when I turn my lights on but no odometer, airbag or brake light, etc...