When should the fuel pump come on when switching the ignition switch
on?

I cannot hear it when I switch the ignition on before start.

Thank you
Walter

 

If yours is a late Series II with the fuel injected 4.2 the pump won't come on until you turn the key to 'start'. This provides fuel pressure while cranking the engine. After the engine starts a switch in the Air Flow Meter powers up the fuel pump circuit.

Put the gearshift in "D" and turn the key to 'start'. You should hear the fuel pump run if you are in a quiet environment. It's just a small 'hummmm'


Cheers
DD

 

Walter:


My favorite state, second only to my home state, Texas. After New Mexico, come any of the others. A distant last, is the one I now live in. Great place, when we came in 55. Steadily detiorated ever since. Now, disgusted with the politicians in charge here. And the "anti everthings" that "protest" just to protest. A welcome place for anarchists to destroy property, under the guise of "peaceful protest. The latter, I respect. But, only when it does not impede the rest of us from going about our business.


Apologies for the rant. I do have a Jaguar to fix later today....




On topic: Although the Haynes book is confusing, you m ight find the proper schematic for your car there.


Carl
Carl.

 

Thanks Doug!
Should,nt I hear the pump before starting the engine?

The key is switched to ignition first, so the pump should start up, and the next
step is to start the engine, am I right.

There is a small switch in the flow meter that is closed when the flap is still
closed, so I suppose that is the pump switch.

Walter

 

No it doesn't work like that. When you turn the key to start the engine, the fuel pump will start, not before. There is a small switch in the flow meter that closes when the flap moves but this circuit is bypassed when the ignition switch is in the "Start" position. When you relax the key after the engine starts, the circuit to the pump is then maintained by the mass flow meter switch.

This tiny little switch caused me some heartache back when I had a 1980 XJ6. It was common after some years for it to get weak and occasionally to fail to maintain contact. The fuel pump relay then opened, the pump stopped, so the engine did too. All this while you are overtaking somebody and a large truck is approaching in the opposite direction !!

Not one of Lucas/Bosch's best efforts !

Have a read: -

http://www.jagweb.com/aj6eng/42efi/index.php

There is a section on trouble shooting at the end