AEM 30-6905 Universal Programmable EMS-4 - Manual (Page 136)

Page 136 of 279 EMS-4 Install and Tuning Guide_Rev 1.6

(Power x BSFC) x (1 + Safety Margin) = pounds/hour

Pounds/hour / 7.25 = gallons/hour.
An example of this equation is:

500 hp gasoline engine using moderate boost with a 30% safety margin

(500 x .625) x 1.30 = 406.25 lbs./hr.

406lbs/7.25 = 56 gallons/hour.

If the pump that is being considered is rated in liters per hour, use the conversion factor
of 3.785l/gallon. The pump described above would be rated at 56 gallons x 3.785 liters =
211.96 liters/hour.
In the fuel pump sizing, always use a safety margin greater than 20%.
Fuel Pump Location
The fuel pump should be located at a level that corresponds to the lowest part of the fuel tank.
This does NOT mean that the pump should be in a vulnerable position such as hanging below
the tank. The pump should also be positioned so that it is protected from the road hazards
(speed bumps, curbs, road debris etc.). In the event of an accident, the vehicle structure
around the fuel pump should not deform to a point where the pump and its electrical
connections are compromised.
The wiring for the fuel pump MUST be rated for the amperage of the pump. As with all high
current wiring, a fuse rated for the amperage of the pump should be used. It is always better to
err on the large side for the wire size. The ground for the pump must be the same size as the
power lead and be mounted to a location that is clean and clear of any undercoating or paint.
Fuel Hoses and Routing
Even with proper injector and fuel pump sizing, a fuel system will not flow adequately unless the
hoses that deliver the fuel to the fuel rail are of sufficient size and are routed properly. On
systems that use the PNP version of the AEM EMS, there is no need to replace the fuel delivery
hoses unless the engine is heavily modified.
NEVER route fuel hoses through the interior of a car. Put bluntly, this is a dangerous thing to
do. Whenever possible, use a delivery tube to make the connection from the pump discharge to
the filter in the front of the car. The lines should be rated to withstand at least twice the
maximum pressure of the EFI system.
Using the above parameters of our sample engine with moderate boost, we expect to see
pressures in the 65-70 psi range. This will require a line with at least 140-psi rating (most AN
hoses exceed this by a large margin). When routing fuel lines, it is imperative that they are
protected from road hazards and the exhaust system. The fuel line should NEVER be routed