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Curtis, Australia Car Mechanic
Category: Australia Car
Satisfied Customers: 1606
Experience:  Qualified Automotive Mechanic, LPG & Airconditioning Diagnostic Technician.
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I have just bought a 1974 Jaguar XJ6 Series II 4.2 Litre 4

Customer Question

Hi Richard,
JA: What is the model/year of your Jaguar?
Customer: I have just bought a 1974 Jaguar XJ6 Series II 4.2 Litre 4 door sedan with twin carb. The car was sitting for 8 years due to a fuel pump problem. I replaced both pumps and put fuel in both tanks and the car fired up. I have a problem. It seems that on one fuel tank it runs perfectly, but runs out of fuel quickly. Then I flick the switch and although it runs, loads of fuel comes out the carburettor overflow pipes on both carburettors. Im lost as to whats happening.
JA: Have you ever replaced the fuel pump, or is this the original?
Customer: Yes. I had to put in Generic Goss Fuel pumps. which they state are a perfect replacement. They seem to be pumping the fuel very well..... maybe too well
JA: Are you fixing your XJ6 yourself? What have you tried so far?
Customer: Yes I am.
JA: Anything else you want the mechanic to know before I connect you?
Customer: no. Please connect
Submitted: 9 months ago.
Category: Australia Car
Customer: replied 9 months ago.
Expert:  Gary replied 9 months ago.

Hello there,

I'm sorry you have not been attended to as yet.

Sounds like your fuel pressure is too high, one pump is causing high consumption, but not quite flooding, the second is just higher causing the flooding condition.

The best way to combat this is to add a pressure regulator before the carburettors.

SUs like up to 3 psi, and you find a steady 3psi all the way through the rev range to be ample.

Hope this helps.