A trip to America's Heartland gives us this first look at Aeromotive's newest sumped-tank Mustang fuel system, highlighted by an A1000 pump and a 100-micron filter mounted inside the sump.
Horse Sense: Our test Mustang for this first-look tech report is Aeromotive owner Steve Matusek's clean '86 GT convertible. It has been in Aeromotive's stable for what seems to be an eternity, as evidenced by its early version of ProCharger's D-1 supercharger system and a vintage Cartech 5.0 bread box-style upper plenum that brings back memories of Mustang days gone by. The ragtop 'Stang is the same lab rat used to develop the first sump-tank fuel system for Fox Mustangs in 2001-a concept that may not have ever seen the light of mass production had it not been for the suggestion of Editor Steve Turner.
How many of you have ever had to think twice about engaging in street warfare with a 'Stang because it was sporting a sumped fuel tank?
There's no doubt that the sight of a deep fuel tray, an enormous pump, and AN -10 braided line at the back of a street Mustang is intimidating, and it can cause great concern about the radical beast that may be underhood of the super-fueled 'Stang you've rolled up behind.
Let's go back in time for a moment. Before sumped fuel tanks became hip, 'Stangbangers' original solution for improving fuel systems to support more horsepower was to add bigger and louder external fuel pumps. As the suction of a fuel system is arguably its most critical element, adding a big pump proved to be only somewhat effective, mainly because of the limited capacity of OEM pickup tubes, which pull fuel from the small, baffled section of stock tanks.
The baffled sump tray (above) represents the company's first foray into controlling fuel inside the tank during aggressive driving maneuvers (launches, braking, and cornering). Although the concept was an improvement over the stock tank from a control standpoint, the baffled sump left a lot to be desired in the area of low-fuel-level efficiency and the ability to keep fuel temperatures reasonably cool. Aeromotive introduced its box-style sump system (below) in 2001. This setup features higher walls and an independent reservoir for returned fuel, which cools gas before it reaches the pump.
Upgrading to oversized pickups also had limited success, as stock tanks' baffled areas are designed to feed fuel from the bottom. They're sized for the factory pump, not high-volume aftermarket pieces.
At fuel levels below half of a tank, external pumps can suck the baffled chambers dry before they're able to replenish, which is no good for engines with power adders. Other problems associated with using fabricated pickup assemblies in stock fuel tanks include pump cavitation, vaporlock, irregular fuel pressure, exaggerated pump wear, and lean conditions during low and high loads.
Aeromotive Fuel Systems has been the front runner in complete, bolt-in, return-style fuel systems (tank, pump, regulator, lines, and fittings) for '86-'97 Mustangs. More times than a few, it's the business end of Aeromotive's A1000 or Eliminator system you're looking at when you find yourself following a sump-equipped 'Stang. The company's original EFI Mustang system was developed as a method of satisfying increased fuel needs, while eliminating the problems inherent to the suction side of the fuel system, all based on the gaining popularity of power adders for street/strip 5.0 'Stangs and the higher performance levels enthusiasts were achieving with nitrous and superchargers.
Aeromotive's early stab at a solution was to install a drag-race-style sump in the factory tank. The sump featured extra baffling to prevent starving the pump during hard takeoffs and extreme cornering and braking on the street or track. It's also outfitted with a billet port in the factory location for return fuel. The idea behind a sump also was to ensure there would always be enough fuel available to feed the system when the fuel level is low and as its temperature increases.
Low-fuel-level efficiency was the primary focus for Aeromotive's second generation of sumped Mustang fuel tanks, which until now, have been the tanks that most street and race enthusiasts go to when it's time to step up their Ponies' fuel systems. The updated tanks feature a revised design in which the walls of the sump are raised almost to the top of the tank, and the fuel returns to a separate area at the back of the sump. Returning fuel into a dedicated reservoir minimizes aeration and cools the fuel before it enters the suction side of the sump.
This photo depicts a component-by-component breakdown of Aeromotive's new upgraded sump box. The box itself is the same as the second-generation piece, with redesigned baffling to facilitate internally mounting an A1000 fuel pump. A point of interest on the filter side is the filter-housing assembly, which is designed to rotate and seal off fuel passages any time the billet filter cover is removed. This feature is notable because it enables enthusiasts to remove and service the 100-micron filter without spilling fuel or losing any pressure in the system.
Although each new sump/pump/tank assembly is sold as a finished and complete unit, Joe walked us through the process of how the unit comes together. Once the pump, filter housing, filter, AN -12 hard line, and baffle are installed and the sump is welded into the fuel tank, gaskets are inserted between the fuel-pump canister and filter housing and the sump's front panel.