High Pressure Fuel Pumps - Location and Function
The LS1 requires a fuel rail pressure of about 60 psi and as such needs to be supplied by an aftermarket Walbro Fuel pump. With most low wing aircraft there are two pumps to supply the engine with fuel. There is the engine driven pump and an auxiliary pump that is used during take-off and landing.
To maintain this redundancy and because the LS1 doesn’t have an engine driven pump, I have installed dual Walbro high pressure pumps to supply the fuel to the fuel rail. These pumps are gravity fed from a long cylindrical header tank mounted above them. This ensures that the pumps are wetted in all but the most extreme of flight attitudes.
I have plumbed them in paralell and have wired them to two separate power supplies. I will have the primary pump running all the time and the secondary will be switched on by my Vertical Power system based on flight mode. I have wondered whether or not I will change the designation of primary and secondary at each annual inspection so that any one pump isn’t overused.
I mounted the two pumps on brackets that I mounted to the co-pilot side of the centre tunnel. Each pump is secured to the bracket by two stainless steed worm gear clamps. They each have a check valve so that they can operate in parallel independently.
The fuel is routed from the tee just past the pumps up out of the centre tunnel and forward to the firewall where it is secured to the stiffener rib running diagonally down and outward where it turns 90 degrees through the firewall and into the back of the gascoaltor.
Tomorrow I will explain the dual low pressure pumps.
Dave