Hello !

On a XJ40 1990 4.0, I encounter an embarrassing problem : when I turn the ignition key, the engine starts right away, but immediately stalls.
What I've checked :

• I have ignition : I took out a plug, and when running the starter I've sparks.
• I have fuel : i took away the hose from the fuel pressure regulator after the injectors, and when I shortcut the pump relay, the fuel is going out. (I've also tried to start the engine while the pump relay was shorted)
• If if put start pilot inside air input when cranking, the motor is running as long as put start pilot inside (I used brake cleaner for this test, and only for 5 or 6 seconds)

I ordered a new CPS sensor ... it will arrive in 2 days, but in the meantime, may be do you have any other idea ?
Thanks !

 

I suggest looking at the electrical section of the ignition switch. The part behind the lock cylinder. I've had other vehicles that would act that way when their slide switch was bad (a different kind of switch but same result).

 

Thanks Jerry, I will check after replacing the CPS sensor which is currently in the mail.
During my checks, I forgot to look at the RPM needle to see if it was spinning at 200RPM when cranking ...

 

So, nothing better with the new CPS.
BUT !

I tried to disconnect the mass airflow sensor and ... the engine started right away and it idles pretty good, and it revs good.
As soon as I connect the MAF again, immediately the engine stalls ! I think I've found the guilty part.

But, I did not know that a faulty MAF could cause the engine to not start like this !