How is the airflow meter intended to work in conjunction with the fuel pump?

If I turn the key to on, the pump doesn't prime like my XJS, but if I lightly press on the flap in the airflow meter, voltage to the pump relay changes from 7v to 12v and it turns the fuel pump on. It stays on as long as I press the flap enough to operate the relay.

What is going on here? Idk if its a timer, but I know the XJS pump comes on a few seconds and then turns off. What is the XJ6 supposed to do?

I noticed it gets 12v from the starter circuit, so does the XJ6 not prime, but instead gets fueled during starter operation and then when air is moving past the airflow meter(running), it turns the pump on?

 

No ‘prime’ function on the Series III 4.2 fuel injection.

What you’ve described is all normal function.

Cheers
DD

 

It's supposed to be a safety feature. There are two tiny contacts in the MAF that close when the flap starts to open, so if the car is in an accident, the engine stopping causes the fuel pump to stop as well. However there is an inertia switch that provides the same function. These two little contacts can eventually cause more danger than what they are there to prevent, by failing to maintain continuity when the owner is driving the car. I nearly had an accident when overtaking when the contacts failed whilst I was overtaking ! This issue is mentioned in Roger Bywater's article on the XK EFI system on his website.

Fuel injection and the Jaguar XJ6 4.2 Series 3 / AJ6 Engineering

When starting the car, these contacts are by-passed until the ignition key is returned to "Run" from "Start"

 

Okay guys, thanks for confirming. I figured out the airflow meters involvement doing electrical "diagnosis" trying to figure out why I didn't have pressure with the key on, so I'm glad to see thats just normal. I could see where it was bypassed during starting in the electrical diagram, but was scratching my head as to whether that was correct since it differs so much from the v12.

On a side note, I noticed the air temp sensor pulled from the airflow and tucked back into the insulation. What effect does this have? I suppose its on fuel trim?

 

Presumably yes, it has just a 'trim' function. But the air temp sensor on this system very seldom comes up in discussion so I (for at least one) don't really know any specifics

Cheers
DD