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Discussion Starter #1
Ok guys, crazy problem I am having.

[07 with SC]


Randomly, about every 4-5 months I jump in my truck (after just driving), start, it runs for a sec. and then just dies.

Try to restart, runs for a second, dies.....

Almost 100% sure this is a result of the fuel pump not running.


-Checked EVERY fuse in and out. All seem to be fine.
-Swapped all relays (just flipped with a relay below) no change.


Seems if I let it sit for a while it starts and runs fine again. It also seems that every time this has happened its always been pretty hot outside. It usually is about an hour and then like it never happened. WTF!!!!



I cant figure out what is going on. Its serious enough that it ruins my day. I carry a fluke with me and spare fuses JUST for this issue. I have called AAA for a tow but it magically fixes itself before they get there.


I cant reproduce the problem and there are no other elements to get clues about the cause.


Please.....any thoughts would be appreciated. This one has me BAFFLED!!!

~JH
 

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I've only had one fuel pump die in any vehicle I've owned and that's what it did. It would go as I was driving (it was summer, so hot) and would work again after cooling off. Once I got stranded and called for a tow, by the time the truck got there it started again. So, from my experience, sounds like a fuel pump going out.
 

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When it happens again check to see if the little truck symbol next to the clock is flashing. If it is, the engine immobilizer did not recognize the ignition key chip. It will run for a few seconds then shut the engine down. A second "chipped" key on your key ring can sometimes cause that to happen.
 
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When it happens again check to see if the little truck symbol next to the clock is flashing. If it is, the engine immobilizer did not recognize the ignition key chip. It will run for a few seconds then shut the engine down. A second "chipped" key on your key ring can sometimes cause that to happen.
Agreed. Pumps die they don't work some of the time. Key or sensor for immobilized is more likely. Fuses don't heal themselves. Relays can stick but usually just stop working.
 

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Next time it happens, take a rubber mallet and knock on the bottom of your fuel tank. If it a dying fuel pump that will sometime work. If it's an immobilized issue, it'll throw a code in you PAT module. It'll be a history code, but it'll be there.
 

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Its the key/immobilizer.

I found this out, too. If I leave the key in the ignition for more than a couple days, the immobilizer loses communication with the chipped key.

When I get that temporary start issue, all I have to do is pull the key out and insert it opposite the way it was.

My truck is garaged in a locked garage, so I don't take the keys with me. Same for work. Secure parking. One less thing to carry around. But I do pull the key now and put it in one of the drink holders so this problem doesn't happen.
 
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I wish I had that kind of confidence with secure parking. In my locked garage behind a locked gate in a fully fenced yard in an arugually very low crime area my keys are locked in the house.

Sent from my SM-N900W8 using Tapatalk
 

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I know. Still its helped more than hurt. Several times I needed to loan out the truck at the last minute for some emergency. Take the truck and get your issue taken care of.
 

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Its the key/immobilizer.

I found this out, too. If I leave the key in the ignition for more than a couple days, the immobilizer loses communication with the chipped key.

When I get that temporary start issue, all I have to do is pull the key out and insert it opposite the way it was.

My truck is garaged in a locked garage, so I don't take the keys with me. Same for work. Secure parking. One less thing to carry around. But I do pull the key now and put it in one of the drink holders so this problem doesn't happen.
This ^^^.

I've had an insane level of frustration that parallels the symptoms described above on a 1997 Infinity I-30 car. And after two months and endless crazy crap (new battery, new mass air flow sensor, etc) finally realized it was the anti-theft system tied to the key FOB that had gone bad. Car would run for a mile or so then start bouncing like a bucking bronco. Fuel pump, if you will, turning on-and-off. Crazy shit.
 

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Discussion Starter #10
Its the key/immobilizer.

I found this out, too. If I leave the key in the ignition for more than a couple days, the immobilizer loses communication with the chipped key.

When I get that temporary start issue, all I have to do is pull the key out and insert it opposite the way it was.

My truck is garaged in a locked garage, so I don't take the keys with me. Same for work. Secure parking. One less thing to carry around. But I do pull the key now and put it in one of the drink holders so this problem doesn't happen.

Every time it has happened to me I had just driven it 10 minutes before; like stopping at a store going in, getting a soda and then it happens.

-ALSO it happens if I just turn off my key and go inside with my keys in the ignition (*its happened at work in a gated facility and I leave my keys in the ignition if someone need to move it). Same time between turning it off, going inside and it wont start 10 or so minutes later.



And....

It runs (has spark) for a few seconds before it dies. Would the immobilizer just cut fuel? I would think if it was the immobilizer it would also cut spark.



Thanks all for the comments!

~JH
 

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Nope ... the immobilizer shuts off the fuel pump.
 
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Discussion Starter #12
WOW thanks guys! I had been dealing with this for a while and now am 100% confident that the chip in the key is the problem.

Now....


Why is it happening? Its rare but does happen and its NEVER a good time to be stranded. Is there something I can do to prevent this?
What can I do when it happens? (flip key, just wait or other)
Should I buy another key?
Can I bypass the immobilizer?

Thanks for any thoughts.

~JH
 

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Since I figured it out, I've never given it a thought. I just drive it and enjoy the truck.
 
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