We are in a world where most of the issues involved in swapping an LS into something have been scienced-out. However, occasionally, we run into an issue that takes a little solving. Recently, one of our guys, Sean, who recently LS swapped his 1994 Toyota Land Cruiser to make it a more capable off-roading unit, but ran into a fuel pressure issue immediately after the swap. Not good when the truck is also his daily driver.
The LQ9 has been opened up to a 408 and is quite a stout combination, so Sean upgraded the truck to a Walbro 255 fuel pump along with the popular C5 Corvette-style fuel pressure regulator and filter combination unit from Wix. However, he quickly realized that the C5 regulator was allowing way too much fuel pressure with his combination, and causing his tuner fits. Obviously this is exactly why adjustable fuel pressure regulators exist.
The 10-micron filter element is replaceable, and the housing is built into the side of the regulator itself — no connectors or adaptors here. The thread you see at the base is for the filter housing cover to screw onto.
Part of the reason Sean used the C5 unit in the first place, was the convenience of having the filter and regulator in a single unit. The funny thing about that, is when he came to us talking about his issue, we remembered playing with a new product in our meeting with Aeromotive at the MPMC Media Trade conference only a few months prior.
After speaking with Aeromotive to make sure this was what the new units were designed for, they shipped out P/N: 13146. Officially dubbed the “Regulator Fuel Filter Combo” by Aeromotive (a boring name that belies the cool factor in the part), they are available for both EFI and carbureted applications. Obviously they sent us the EFI variant, so that we can get the fuel pressure into the 3 bar (58 psi) range.
The -10AN inlet on the filter housing and outlet on the regulator allows for use with a variety of fuel line sizes. In this application, space was more of a concern than flowing a metric ton of fuel, so we used -6AN fittings from the stock fuel lines into the filter-regulator combo, and a -6AN to 5/16-inch hose barb fitting to tie in the return.
Looking at the Fuel Pressure Regulator / Filter Combination
Let’s take a look at the hardware. The fuel pressure regulator portion of the unit is designed to be adjustable for output pressures between 40 and 70 psi with a fuel pump sized up to an A1000 unit. The regulator features a -10AN inlet and outlet port, with a -6AN return port. Like most of Aeromotive’s other regulators, the combo unit features a 1/8-inch NPT dedicated gauge port, allowing you to install your choice of traditional dial pressure gauges, or an electronic fuel pressure sender.
Where the cool factor of this unit comes into play, is that the -10AN inlet isn’t on the regulator itself, but rather at the end of the integrated 2.0-inch-diameter aluminum filter housing. Inside the housing is a 10-micron cellulose filter, which acts as the post-pump filter in your system, without running any extra line or hardware. The fuel exits the filter directly into the feed side of the regulator. You couldn’t ask for a more integrated combination. Unlike the traditional regulator brackets, this unit is designed to be mounted with a simple 2-inch filter bracket. Talk about easy installation.
Mounting was exceptionally simple, requiring a simple 2-inch fuel filter bracket. Fuel pressure adjustment is the same as any other fuel pressure regulator, with a lock nut and adjuster screw used to raise or lower your fuel pressure.
Installation and Testing
Discussing the installation and testing of the Aeromotive Regulator Filter Combo is going to be short, because, well, it’s an easy installation, and the thing just works. We mounted the unit on the fender using a 2-inch filter clamp and existing bolt holes. Because we didn’t need the flow capacity of a full -10AN fuel line, we fitted the unit with -10AN to -06AN reducer fittings on the inlet and outlet, and a -6AN to 5/16-inch hose barb fitting on the return port, to tie into the pre-existing fuel return. We then fitted a -6AN outlet on the factory fuel delivery line, and connected it via a length of stainless-braided line. The same on the outlet side of the regulator to the fuel rails.
As far as testing, well, it was as simple as starting the engine, disconnecting the vacuum reference line, loosening the lock nut, and rotating the adjustment screw to our desired 4 bar (58 psi) pressure setting and locking everything down. Boom, done. A little anticlimactic, but at the end of the day, Aeromotive isn’t building this assembly to transform your engine into a 1,000-horsepower beast. It’s been built to solve a packaging issue and work reliably. In this case, boring reliability is an incredible benefit, and it does that well.
After getting the new fuel pressure dialed in, we are dead-on the 4-bar mark. This is a drastic difference from the 70-plus psi we were getting from the C5 Corvette-style regulator and filter combo unit. Now, the 408 has the proper amount of fuel and the tuner can do his thing to make this powerplant a reliable unit for both off-road adventures as well as commuting.
