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Old 05-09-2021, 02:33 PM   #11
fdryer
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Join Date: Jan 2006
Location: NYC
Posts: 45,058
 

2003 L-Series 3.0L Sedan
Default Re: Just died 5 times at stop lights...

After 'M' day if your SO allows it or you schedule time for troubleshooting, suggestions by billr should be considered, especially fuel pressure and injector checks. A f/p gauge connected and observed in different modes may help determine if the fuel pump is worn out without giving up any hints; ignition on engine off, idling, random engine die offs. At all times after ignition is turned on, f/p should remain high and never drop off, sometimes the only hint of either a fuel pump problem and/or fuel filter issue. Injectors are difficult to diagnose.

Injectors are most likely operating and not prone to intermittent failures unless wiring damage occurred from animals chewing on insulation partly made from vegetable matter or chemicals inadvertently creating the aroma of vegetables. Injector testing is either examining spark plugs for fuel after several failed starting attempts occurs or using noid lights to visually see injector pulses during starting, idling or when restarting when the random engine die off occurs. 233k miles is a very long time for a fuel pump. Nothing lasts forever. If you're lucky maybe not replacing a partially clogged fuel filter is causing an intermittent fuel issue. Checking fuel pressure before and after the filter may help eliminate filter problems. Pressure should be the same on both sides of the filter.

To be clear, the crank sensor is the most important part of the EFI system as it generates the electronic clock pulses that allows the pcm to operate; fuel pump, ignition system and injector pulses. An intermittent crank sensor, when it fails, simply kills fuel pump/spark/injectors all at the same time. Engine heat breaks down sensors. A dead crank sensor kills all three - the starter will crank the engine but it will never fire up. Seeing spark means the crank sensor is working as designed.
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