To understand the off-road benefits of fuel injection, all you have to do is drive a carburetor-equipped 4x4 over bumps or at extreme angles. Sure, carburetors can be tuned to work off-road, and some are better than others in the dirt if you know how to tune them, but no carburetor will give you the hiccup-free, run-at-any-angle performance of a fuel-injection system. What’s more, just about every carburetor body or carburetor design is at least 26 years old, meaning parts are old, inefficient, worn, and possibly damaged. While we are happy to play with some inexpensive carburetors that can be made to work well off-road, such as the Motorcraft/Autolite 2100 or Rochester Quadrajet, nowadays the aftermarket has made it ridiculously easy to upgrade to EFI.
The number of aftermarket fuel injection systems keeps growing. One of the newest to arrive on the scene is Summit Racing Equipment’s MAX-efi 500. At $849.97 it is one of only a few systems that cost under $1,000. As with other systems, a few more parts are required to make an engine run. At minimum you will also need a high-pressure fuel pump, fuel line, fittings, fuel filters, and a fuel pressure regulator. After a call in to Summit we soon had on the way a MAX-efi 500 along with the additional fuel system parts recommended by the company. We plumbed the system up to our 38-gallon fuel tank from LMC Truck, and after a few weekend hours we were taking our 1978 Ford F-250, RedFerd, out on the trail.
We started this project with a new 38-gallon tank and sending unit from LMC Truck. The factory tank was 19 gallons, which our 460 would drink dry in a hurry. Our tank and sending unit was old and rusty, so we also got a new sending unit from LMC to match the new tank. The sending unit has to be stretched with an included piece of copper tubing to work in the new larger tank.
To install Summit’s MAX-efi 500 kit, we also needed a passel of components to get the fuel from the tank to the injection unit. We ordered such Summit-branded parts as -6 and -8 fuel line and fittings, a fuel pump, filters, and an EFI-ready fuel pressure regulator. The MAX-efi 500 kit costs $849.97; the additional fuel system components were $542.31.
Any old truck that’s getting a new fuel tank is going to need new fuel hoses. Every old fuel filler neck we ever met is set in its ways and hates change. Any attempt to move them to a new tank caused them to crumble into pieces, so do yourself a favor and grab a new one from LMC like we did.
The larger tank from LMC is a taller version of the factory tank. Mounting it is fairly easy (as far as mounting a tank goes). Included spacers and new bolts make up the difference so that factory fuel tank mounting straps will hold the new tank in place. We also added some cloth to the straps to prevent rattling and wear on the new tank and then welded an AN -8 steel fuel bung onto the lowest point of the tank for the fuel pickup.
The first part of the fuel system runs from the tank to a prepump fuel filter of 100 microns and then to the pump. We are using -8 braded nylon hose and rebuildable fittings. The fuel pump also needed a male -8 AN to straight-cut male -10 AN O-ring.
The rest of the fuel system from the fuel pump to the throttle body consists of an -8 to -6 reducer (the blue anodized fitting on the pump must be used because it has a check valve) then -6 braided nylon fuel hose running to 3/8-inch metal fuel line and then back to -6 braided nylon into a 40-micron filter, a fuel pressure regulator set at 58 psi, and then on to the MAX-efi 500 throttle body.
We made a mount for the fuel pump using a piece of 3/16-inch steel bar, a band clamp, and most of a rubber isolator for a bypass shock reservoir. This one time, at band clamp . . .
Along roughly 6 feet of Ford’s inner framerail we ran a section of 3/8-inch steel tubing with double-flared fittings and adapters to -6 AN. The silver hex is the double-flare fitting, brass, a double-ended 3/8-inch flare to 3/8-inch flare; the black is an aluminum anodized 3/8-inch double flare to -6 AN male adapter.
The wiring of Summit’s MAX-efi 500 is downright simple. One lead is a ground, one goes to the positive side of the battery, one is key/run power (requiring a full 12 volts during run and start key position), one is for a tachometer signal (we’re running an MSD 6L that’s not required but makes this that much more simple), one wire can be hooked up to start an electric cooling fan via a relay (our truck has a mechanical fan), and one powers the fuel pump. So that’s five electrical connections for us (six if you’re using an electric fan). Simple. The rest of the harness is preterminated with four connectors: one for each injectors, a TPS sensor, an IAC motor, a MAP sensor, a supplied engine coolant temp sensor, a lead for the O2 sensor, and two leads for the handheld controller used for initial startup, tuning, and to see engine info.
The supplied oxygen sensor comes with mounting instructions and a nifty mounting plate with a gasket, held in place with band clamps. That means you don’t have to weld to make this system complete. Or if you are like us and have a welder handy, you can also order an 18mm-by-1.5 pitch weld bung for a more worry-free installation of the oxygen sensor.
Our intake manifold coolant temp ports were full—which is to say, we found only one and it already housed the factory engine temp sending unit. Engine temperature is one of only a few gauges we think are worth having, and while the MAX-efi 500 would keep an eye on the engine temp even if we eliminated the factory sender and gauge, we still would like to know that info. So we decided to add this T-fitting and run both. Sure, the temps will be slightly cooler than if the sensor were in the intake, but the temps these sensors collect should not be too far off from the truth.
With the fuel system sussed out and installed and the wiring in place, we mounted the throttle body to the factory steel intake manifold on RedFerd’s 460. Throttle linkage hooked up using the same parts that were on the old Holley carb that came off the truck. Our kickdown lever going to the Ford’s C-6 is not hooked up, but that’s OK with us because we know how and when to downshift if necessary and if we get annoyed we are sure we can come up with a solution.
The MAX-efi 500’s computer can be mounted inside the vehicle or under the hood. This spot on top of the inside fenderwell made the most sense to us, but it may need some waterproofing if we ever want to take RedFerd to play in the muck and mire. We also had to set the fuel pressure regulator at 58 psi using a gauge temporarily mounted to the regulator and used 3/8-inch rubber and factory fuel feed line as the return to the tank.
The Summit Racing Equipment MAX-efi 500 also came with this handheld touchscreen controller for setting the parameters when you first install the system. Feed in the displacement, camshaft specs (ballpark is fine), and so on, and the computer does the rest. The controller can also display the systems sensors on a large gauge screen as you are driving, but the controller isn’t necessary for the system to function. After our info was input, the system fired right up, then we set the mechanical idle speed per the instructions and drove the truck a few times. So far the new and improved RedFerd has run well on our quick shakedown runs. We will give you a more involved review once we get more mileage on the system.