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rpmdiag, Tech and Instructor
Category: Jaguar
Satisfied Customers: 8147
Experience:  Since 1975
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1989 XJ40 XJ6 stalls and usually does not restart. Have

Customer Question

1989 XJ40 XJ6 stalls and usually does not restart. Have replaced Crankshaft sensor, fuel pump, fuel filter, spark plugs, plug wires, distr cap and rotor, spark coil. Currently have removed ECU and inspected connectors for water or corrosion. None found. Usually will start after waiting 10-15 minutes. Looking for ideas. Mileage 114,000
Submitted: 1 year ago.
Category: Jaguar
Customer: replied 1 year ago.
Car is reassembled and running however I expect it to fail again. My thought is that it is a reoccuring CAS problem even though a new sensor has been installed. Resistance of new sensor measures 1300 ohms. I have another new sensor never installed also measures 1300 ohms. My question is, is there any history of the AJ6 old style CAS problems related to magnetic loop gap, particles on the toothed wheel, or other esoteric items. I note that Jaguar redesigned the CAS in later models where it is a different sensor inside of the old distributor assembly.
Expert:  rpmdiag replied 1 year ago.

Hi, I’m Ron and I’ll be helping you today.

Before we get started though,Please understand that I don't know your skill level or tools you have to assist us. Also understand that I can't see,smell, hear or touch the vehicle either, so your patience is appreciated.

My goal is to make you happy and get a great rating in return for my time.Sometimes I have to give you bad news that I know you didn’t want to hear, so please don’t shoot the messenger.

When it doesn't start, check for a strong blue spark at the plugs with a spark tester. Also, check the fuel pressure with a gauge. We need to know what we're losing when it won't start.

Thanks, Ron

Customer: replied 1 year ago.
Hi Ron, thanks for taking some time with this. This is the second Just Answer on this car. First one was back in March. You had suggested all of the stuff that has been done. I am getting frustrated taking it out on the road and having to deal with getting it pushed away from traffic so no way to work on it when it quits in traffic. I have discovered that I have missed one part, the Ignition Module located under the spark coil. The sequence of events fits this type of failure as only seems to quit when temperatures are high. I have a pretty complete electronics lab and do electronics design as well as a hobby of restoring aircraft. I have tracked down a lot of odd problems in my life so not afraid to use engineering skills to solve problems in situ.
Expert:  rpmdiag replied 1 year ago.
You're right, those modules can and do fail. I usually test them with a hair dryer while the motor is running, making it good and toasty.
Thanks again, and please don't forget to rate me and keep this link in case you need me again later on.