I have an 08 jk with 160k miles on it. I went to start it up last week and it cranked ran fine for 7 seconds then the fuel pump shut off and the engine died. It has displayed the same behavior ever since.

My first thought was key related, but the security light turns off well before the engine starts dying. I have tried unplugging the battery and letting it sit for about 5 hours to reset everything but that did not change the behavior.

It seems that at the end of POST(power on self test), the fuel pump is being disabled. If i crank it and hit the gas it revs just fine until POST completes, then it dies anyway.

I have looked through posts about the TIPM giving people issues, but I have not seen anywhere that people make it 7 seconds then loose fuel pressure.

If anyone knows what might be happening or how I might bypass the issue to get it to a shop, I'd appreciate it a lot.

 

Good of you to note the security light. This thread about the wireless control module may be useful to you ...

https://www.jk-forum.com/forums/stoc...stalls-272572/

 

Hey Mark,

As I said before. I have ruled out the wcm as the issue. The key is recognized after 2 seconds and the security light turns off. The issue doesn't occur for about 5 seconds after that happens.

If I am quick enough when i crank it, I can drive the jeep about 5' before it shuts down the fuel pump. So i know the pump is working initially and am looking for what could be causing it to be shut off at the end of POST.

 

Hey Mark,

As I said before. I have ruled out the wcm as the issue. The key is recognized after 2 seconds and the security light turns off. The issue doesn't occur for about 5 seconds after that happens.

If I am quick enough when i crank it, I can drive the jeep about 5' before it shuts down the fuel pump. So i know the pump is working initially and am looking for what could be causing it to be shut off at the end of POST.

 

You've exceeded my experience with this system. However, why do you refer to POST? I don't believe that the security system accepting the key because the light goes out is a POST. It is the security system accepting the key. Your symptoms point to the security system accepting the key, but it's still not allowing the vehicle to start. I'm not certain how the "good key" signal is distributed from the WCM to the rest of fuel system and dash light. Sorry, but it's going to take someone smarter than me to help you with this.

 

Power On Self Test is the process the computer runs through as it checks that all major systems are working correctly. Key security is only one of the tests done during POST.

 

Of course. The computers my daughter and I have built over the years run a POST. However, "POST" is not a term that is used in any of the documentation I have on my 2007 Jeep JK. There are checks that are accomplished when the Jeep is started. Some tests run as the Jeep as driven, some aren't. Here are a couple related pages from my owner's manual. Note that it says the SKIM light extinguishing means no malfunction is detected. It does not, however, say that the light will turn on if a malfunction is detected after that. If you looked at other systems, you'd see that they clearly spell out that the light will come on, sometimes flashing, to indicate failures after start. IOW: Does the SKIM light going out at engine start really mean that the system is 100 percent good to go? Will the light come back on later because system checks are being run continually if there is a malfunction? Is it possible that an undetected problem will allow the SKIM light to turn off, but then send a signal to the system to shut down? Not knowing what checks are run and when is why I indicated that my knowledge has been exceeded.

 

Yep, POST is definitely a computer term and not applicable to the JK. Nobody is checking RAM here. It does a quick gauge check but nothing too extensive.