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Richard
Richard, Jaguar Technician
Category: Jaguar
Satisfied Customers: 15437
Experience:  12 years at a Ford/Lincoln Mercury and Jaguar dealer as technician and shop foreman.
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03 jaguar intermittent no start no fuel disconnect battery

Customer Question

03 jaguar intermittent no start no fuel disconnect battery usually overnight car starts
Submitted: 1 year ago.
Category: Jaguar
Expert:  Richard replied 1 year ago.

So there was no fuel pressure hut we had spark? Would the engine start on supplemental fuel like carb cleaner.

Customer: replied 1 year ago.
it would start with supplental fuel
Expert:  Richard replied 1 year ago.

Ok it can be a bad fuel pump or the control module which energizes the pump. The module is actually the rear electronics module in the passenger side rear of the trunk. To be sure we will need to check for power and ground to the fuel pump connector under the passenger rear seat. We also can try disconnecting the mass air flow sensor on the air cleaner to see if the engine will start and run. Before doing that I recommend we have the vehicle scanned for the stored fault codes because when disconnecting the sensor we will induce faults. Let me know.

Customer: replied 1 year ago.
mass airflow disconnect does nothing what color wires should i check for power and grounds at module
Expert:  Richard replied 1 year ago.

I would go right to the pump connector. They are the thick red and yellow wires in the middle of the connector. Remove the rear seat cushion by moving the release lever then remove the large black round cover on the passenger side and you will see the connector.

Customer: replied 1 year ago.
ok
Expert:  Richard replied 1 year ago.

With a digital multimeter set to DC volts place one lead to the red and the other lead to the yellow. Crank the engine and we should see around 9-10 volts.

Customer: replied 1 year ago.
engine started on its on power on red and yellow wire constant with key in on position, dont cut off after a afew seconds
Customer: replied 1 year ago.
cant find module
Customer: replied 1 year ago.
where is rear module
Expert:  Richard replied 1 year ago.

If you remove the side trim on the passenger side trunk there is a metal bracket. Remove the 10mm bolts on the bracket as the module is mounted to the backside of it.

Customer: replied 1 year ago.
have about 7.5 volts when conected to yellow and red wires at pump while car is running. found module
Customer: replied 1 year ago.
car went back to no start, voltage on yellow wire at pump when in run position i 12 volts , in crank position drops to about 1 volt
Expert:  Richard replied 1 year ago.

On without a Jag factory tool we are limited but I don't like the voltage reading so it can be the rear module.

Customer: replied 1 year ago.
sorry i got tied up all yesterday, but i switched out the rear module ,still have ocasional no start but will eventually stat after a few tries , when running at idle fuel pressure is about 34 psi
Customer: replied 1 year ago.
i also have access to a maxi das 708 scanner
Customer: replied 1 year ago.
are we done richard
Expert:  Richard replied 1 year ago.

34 is slightly low on these vehicles. So I wonder if the pump is the problem.