Does anyone know why some Cosworth's have a second fuel pump relay wired in, usually in the boot? I am having some trouble with my fuel system, and I cannot figure out why an additional one is needed?

Thanks in advance

 

You don't mean the cutoff switch in the boot?

 

No, I am pretty sure that RS500's don't have an inertia switch. This is a seperate 40A realy wired into the original fuel pump wiring coming from the original relay at the front of the car.

Cheers

 

One typical cossie problem is the reduced voltage at the fuel pump due to the high resistance of the old wiring/connections. This results in poor fuel feed to the fuel rail. Using the old fuel pump feed to switch a new relay in the boot allows the pump to take a new (fused) feed straight from the battery.