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Discussion Starter #1
Im looking for some info on the immobilizer system and possibly the fuel pump cpntrol module and how they function.

I drove it to work today without issues. When I started it on lunch it reved up like normal and idled for a second and shut off. After that it was just a solid and healthy crank no start.
If it sits for 5 minutes or so, I do hear the fuel pump prime , and it will start for a moment and then die.
It will stay running on an alternative fuel source so Im positive I've got spark.
Seems to me there is something interrupting the signal to the pump. It will prime without issue every attempt as long as I let it sit a few minutes in between tries.
I only got as far as testing for 12v with key on at the fuel pump module, and making sure the constant ground had continuity.
I also swapped the fuel pump relay around and that did not help.
They flashing key on the dash does go out when I key on.
I have a Modis scan tool and it says that the immobilizer is disabled in the information field displays ( not positive I trust this completely and do somewhat suspect a faulty key, also do not have a second key to try )

Any thoughts or ideas greatly appreciated , could not find and TSB or tech tip regarding this issue either.
I also tried repetitive arming and disarming the alarm with the fob, and no change.
 

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I suspect the key also... I would think that if the transmission safety interlock was engaged it wouldn't even crank.
 

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Discussion Starter #4
It does come out of gear without issue and the flashing key on the dash goes away when I insert the key in the ignition. Im not sure if that means its been recognized or just that the ignition switch has been activated
 

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Discussion Starter #5
I don't believe it to be the fuel filter, as the only time im hearing the pump is when its priming. There were also no issues at all leading up to this. Generally in my experience the fuel filter restriction would be more of an issue at high demand / free way driving than start up. I may be wrong.
 

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Discussion Starter #7
you said it will run on a alt. fuel source. that sounds to me like a delivery problem.
I totally agree, I just cant make sense of why I hear it prime. What would cut signal to the fuel pump other than FPCM , immobilizer, or perhaps crank sensor?
 

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Agree with TC, if it will run on an alternate fuel source you have removed the tank, filter, pump and a portion of the hoses. I would do several things:
1. By pass the relay circuit and run the pump directly from a key-on source, but make sure you use a fuse equal to the current fuse in the circuit or something appropriate for the wire size leading to the pump. This will tell you if there is an issue with current supply side to from the pump to the engine. If the engine runs normally, you know it is current supply, if the engine does not run normally, but stays running, then you may have a flow restriction or weak pump.
2. If that works and engine runs normally, then you need to determine where in the circuit the issue exists, typically it will be the fuel pump relay.
3. if this does not work properly, then you will need to determine where your pressure/flow issue exists, by following the diagnosis in the manual.
3a. Attach gauge and test for system pressure, which if not then it may point to the pump or return pressure valve. The pump flow rate can be tested as well as the valves forward and aft pressures.

GL
 

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Discussion Starter #9
So here is where I eat crow.....

It ended up being a faulty gauge / sender.
I had between 8th and 1/4 tank on the gauge.
I decided to add a gallon just to rule it out and it started right up . Has started a few times since without issue.
Womp womp
 

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Don't feel bad, I had a mechanic friend that the same thing happened too. He parked his car and when he went to leave it wouldn't start. he spent a day trying to diag everything only to find out that he was out of gas lol. It's often times the simple things that catch us off guard. Just glad to hear it wasn't anything really serious.
 
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