I have learn that some Jaguar models come with dual fuel pumps and dual fuel relays as a result .So , is there any particular reason as to why Jaguars have been fitted with more than one fuel pump ?
Is it an indication of supremacy of Jaguar or whatnot ?

 

Supercharged engines produce alot more horsepower (about 140 more but it uses 60 HP to run the Eaton unit so you net 80) More HP requires more fuel so the second pump comes on when demand is high.

bob gauff

 

Thank you for this very informative and concise reply

 

Cadillac, not sure if this is what you are after either, but like with the X-Type, the fuel tank has a large bulge in the center to allow the driveshaft to get by. This essentially divides the gas tank into 2 smaller tanks. So, you have one pump that feeds the engine, the other pump simply runs to transfer fuel from the side opposite the engine pickup to the side with the engine pickup. So, the need for 2 pumps is needed.

 

Having two pumps is common on electronically injected diesel engined cars nowadays, one to pump fuel up from the tank, and another, high-pressure, pump to maintain a very high pressure in the fuel rail. The old system of one pump to do the pumping and the metering has almost disappeared.

I have never heard of it on petrol-engined cars.

 

Unless the car is superchraged (S-Type R or the NEW XJ supercharged) the left pump of the 'saddle-tank' is a mechanical jet pump to transfer fuel back to the right side where the electric pump is located. The level senders give an average of the two sides. The system is actually more complicated with additional jet pump, reservoir and variable speed PWM pump returnless system etc. etc.

bob gauff

 

Thanks Therno, Fraser and motorcarman for your valuable inputs ,nice to learn such useful things