This saga began with the fuel pump going out, as much fun as that was to track down a replacement, and install it we thought we solved our problem.

We thought wrong.

With new fuel pump, engine finally fired after lots of cranking to purge out vapor lock, and we left it idle for the remaining clean up and putting away of tools, probably 30min. It idled perfectly normal, steady, no funny smells or sounds. Back to normal we thought.
Turned car off and called it a day.

Just for *****, maybe an hour later I went back out to start it 'just to make sure' and it did start, but within 2-3min it died rather abruptly, as though key was turned off. I was able to start it right back up again, but it wouldn't stay running without constant feathering of the throttle.
Hooking back up the fuel pressure gauge to check for fuel pump function, there was a very slight pulse of pressure when putting the key to RUN (not start) that only went to like 5psi and dropped back to zero just as fast as it got to 5psi. When turning key to START the gauge stayed zero.
Defective fuel pump we thought.

We thought wrong.

I've been tag teaming this with a mechanic friend of mine, so sorry for the holes in the story, but after he had a session with it, determined the fuel pump was A-OK, able to see pressure before regular, and now the no start problem has shifted gears to there being NO SPARK at the plugs. He advised that I try replacing the Ignition Control Module as his research indicated that was the most commonly failed part in the system.

So I got this module, but cannot for the life of me find where it is in the car to change it out.

In the meantime, I came hear and in my reading found that a bad crank position sensor could result in a no start, and that if the tach does not read ~200rpm while cranking starter, then it is a likely culprit. My tach never leaves zero, so going to get a new crank sensor now.

Can someone please advise as to where the ICM is located??
Thank you! These forums are without a doubt what's keeping most of these cars on the road, a big thanks to all the moderators, administrators, vendors, and of course the knowledgeable members that make websites like this worthwhile!

 

Hi EppNation,

Welcome to the Jaguar Forums! It's great to have you with us.

Replacing the crankshaft position sensor (CKPS) is a good idea with zero rpm showing on the tachometer while cranking the engine. Until the new sensor arrives, it might be worth checking the electrical connector for the existing sensor for oil and gunk contamination, a pin backed out of one half of the connector, or other issues.

On the X300 ignition and fueling are controlled by the Engine Control Module (ECM) made by Lucas-Sagem GEMS. Is that the unit you purchased? If so, it is mounted near the right A-pillar behind the passenger side knee bolster. Corrosion on the ECM connector pins is known, but actual module failure is very uncommon.

Here are some documents that may be helpful, courtesy of our forum member Gus:

1996 Electrical Guide:
http://www.jagrepair.com/images/Auto.../jagxj1996.pdf

Engine Management Systems manual (your engine is an AJ16):
http://www.jagrepair.com/images/Trai...20-%202000.pdf

1996 Technical Guide:
http://www.jagrepair.com/images/Auto...1996%20LWB.pdf

For many possible causes of a no-start condition, see this thread, compiled by aholbro1:

https://www.jaguarforums.com/forum/x...ngines-120221/

Cheers,

Don

 

Have you thought about a faulty fuel pressure regulator? Fuel pump works ok, but regulator faulty, dumping pressure from the rail back to the tank?

 

Just wanted to follow up!

Replacing crank position sensor did the trick. I used this one.
Just very coincidental timing I guess for it to go bad within 1 hour of fuel pump getting replaced.

 

Return that ignition control module. That is not a part on the X300 XJ6. I hope Autozone didn't tell you it was. A lot of older cars used that type of device and if it went out, you were done.

Sort of like the crank position sensor (CKPS)! Just a little more expensive, although the car is a Jaguar after all! Getting it from Autozone was probably a good idea for one reason: the lifetime warranty. Let's see how "Dura"ble it is and how long it "Lasts". My bet is that you will need another one within a couple of years. But no worries, lifetime warranty!

 

Good to hear the successful outcome. I've added "RESOLVED" to your thread title.

Graham