[s-type] Long engine crank issue 4.0 V8 2001 car

The issue is on a 2001 S Type 4 liter. What is the normal fuel
pressure drop in the fuel rail over an 8 hour period? A
friend’s car has 35 Lbs at shut off and 20 Lbs after sitting
overnight. The car suffers from intermittent long crank
starting episodes but a test shows fuel pressure instantly
returns to 35 lbs when ignition is turned on. I have also
been advised that the long crank issue may be caused by a
faulty cam positions sensor and/or a faulty crank position
sensor. Can anyone verify this?–
John Quilter 1965 3.8S, 1951 MGTD, 1960 Morris ,1990 XJ6
Eugene, Oregon, United States
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Final resolution of a very, very long standing issue:
This is a response to my post of long, long ago. My friend with the 2001 4.0 S Type (93,000 miles) has been living for over three years with this 10 second cranking situation before the car would start. Because no local California shops or two Jaguar dealers were able to rectify the problem in spite of a new fuel pump and thousands of dollars spent including fuel injector cleaning, all with no resolution, he finally decided to have the car shipped from the San Francisco Bay Area to my local independent British car shop in Eugene Oregon so they could have a go at a final fix. Within a hour and a half the local shop monitored the fuel pressure when shut down and found that it dropped from about 43 pounds to near 0 in a half hour. Because the fuel pump and its internal check valve had been changed earlier, with no improvement, this tech removed the LH fuel rail and injectors and found 3 of the 4 leaking. They ordered 8 new factory injectors, fitted them and the problem was completely eliminated all without the use of electronic engine management diagnostic equipment. It was a simple failure to check the basics. I road tested the car for 4 days and every start was within 1.5 seconds. The previous repairs and incomplete checking of the basics of a FI system is nothing short of shear incompetency. But at least my colleague is now fully pleased with his belatedly repaired car.

John F. Quilter
Eugene, Oregon USA

SOOOOO many times, failure of diagnoses goes directly to not understanding the fundamentals.

Glad you found a shop that gets it!