Chrysler Repair: 99 300M shuts down, recovers in minutes, pulley bolt, crank pulley

Question
My 99 300M has been running great. It has about 95,000 miles on it. The other day after stopping at a store when I got back in it wouldn't start. Cranked well but wouldn't start. After 3min it then started with out a problem ran great. No codes no ck engine light. No hesitation while running. Garage said possible fuel filter, but they are part of fuel pump. Hate to replace it if not the problem. Last night  driving no warning shut off as if you turned the key off. 2 - 3 minutes started up. no codes, No warning. Any Ideas

Answer
Hi John,
Sometimes as the ignition sensors begin to fail they can produce an ineffective signal but not set a fault code. I assume that you are either using a code reader or that the codes are designed to appear on your odometer via the ignition key, so you are not yet seeing a code. I would verify whether or not you are getting spark the next time this happens. Be prepared to quickly remove a plug cap and insert a spare plug, then holding by the insulted cap touch the threads of the plug to the engine block/head while a helper cranks for 5 seconds to see if you get spark the entire time. If not, then it is ignition and not fuel related.
You could check the signal strengths with a voltmeter: one lead is ground (black/light blue), one is 8V ((orange), and the third is the signal wire. It should oscillate between 5V and 0.3V as you rotate the engine by means of the crank pulley bolt with a wrench and of course with the ignition in the run position. You would have to use fine pins to probe the wire insulation to read the voltage between the signal and the ground wires.
The time between shut down and recovery may be too short at this point to do that test. But keep checking for codes until the point where the breakdown is evident. It is also possible that you have a faulty ignition switch or ASD relay so I would listen when you turn the key to run position to hear whether the fuel pump runs for a second and then shuts down, which is normal. Then recheck that the next time you stall. That will tell you if the ASD is the problem (or the fuel pump) but you can also check the 12V supply to a spark plug (dark green/light green) to see if it shows 12V for a second also which would definitely tell you if the ASD is ok.
I am curious to know what you learn.
Roland