Fuel Injection - EFI For Fords

Hot rodding is many things to many people, but the fundamental goal of the hobby has always been to push the envelope, to make machines that are better, faster, and more attractive than they were before we got our hands on them. It's the automotive equivalent to building a better mousetrap, or climbing a mountain because it's there. Over the years hot rodders have found a variety of ways to achieve their goals. Certainly when it came to performance, one of the most common methods was to utilize the latest in factory engine technology. Keep in mind, at one time that meant swapping a four-banger for a new Flathead V-8. Today, it can be simply bolting on the latest in electronic fuel injection.

It may be hard to believe, but better than two decades have passed since a new car rolled down the assembly line equipped with a carburetor. Fuel injection has been the auto industry standard for some time, and it has become widely accepted among street rodders, as well. However, as the small-block Chevy is arguably the dominant engine in our hobby, it's been a GM-only party for the most part. And while aftermarket kits to install the various GM fuel injection systems have been available for some time, the small-block Ford crowd has been left wanting-until now.

Fuel injected 5.0- and 5.8L (302- and 351ci) Ford engines are plentiful and are becoming increasing popular on the street rod scene, something that has not gone unnoticed by Jim Paxton and Dennis Overholser and the gang at Painless Wiring. Both Paxton and Overholser are owners of street rods powered by EFI-equipped small-block Fords, and it was their experience with the combo that prompted them to develop a new wiring harness to give Ford fans the same easy access to electronic fuel injection the Chevy fans have enjoyed. Listed under PN 60510, this new kit is for '86-93 Ford 5.0- or 5.8L fuel-injected engines with a mass airflow (MAF) sensor.

Although this new kit was only recently introduced, we happened to stumble onto one being installed at Dagel's Street Rods. Now, at this point, we would normally detail the installation of the harness, but Painless provides excellent instructions, so there is no need to be redundant. However, don't stop reading just yet because there are some things you want to know and some parts to round up before you begin.

Types Of Systems
Like GM, Ford has produced two distinctly different electronic fuel injection systems: one type is mass air flow (MAF), and the other is speed density. The basic difference is that the MAF system directly measures air flow, which means that it will tolerate engine modifications such as more radical cams, high-flow heads, exhaust system modifications, and so on. Speed density systems determine air flow with a series of sensors and can't cope with engine modifications. Speed density systems were used on '86-88 49-state H.O. 5.0L engines; mass air flow was used on '86-88 California cars and all '88-95 cars ('94s and '95s used a different distributor, so to use those fuel injection systems an earlier distributor must be used).

The key to success with this installation is compatibility of the components. If you choose a used system, get everything from the same vehicle, if possible, to ensure they are calibrated for that system (it's still not a bad idea to check part numbers to make sure nothing has been incorrectly substituted). If you're buying new components, follow the included parts list.

Manifolds
Ford EFI manifolds are unique in that they are made in two halves, an upper and a lower. As the throttle body attaches to one side, this means its location can be moved from one side to the other as engine compartment clearances dictate.

Computers
Ford has used a variety of computers with their electronic fuel injection systems, which one you use will depend on the transmission employed. For automatics use Ford Racing and Performance Parts kit PN M-12071-G302; manual transmissions use PN M-12071-F302. Both come with the computer, MAF, inlet and outlet hoses, and bracketry. If a used computer is to be installed, check the code with your local Ford dealer.

Ignition
To interface with the computer, a Ford distributor (or the aftermarket equivalent) with a thick film ignition (TFI) is required. In addition, the distributor drive gear must be compatible with the camshaft. Cast-iron gears are compatible with solid or hydraulic flat-tappet cams; steel gears are required with billet steel and production roller lifter cams. Most aftermarket manufacturers offer both types of gears, as well as a bronze gear that can be used with either type of cam.

Sensors And Relays
There are a variety of sensors and relays used with this system (see parts list), and some of them look similar but are anything but interchangeable. Most notable are the intake air temperature and the engine coolant temperature senders. Make sure to identify each before installation.

EGR Valve, Sensor, and Regulator
The EGR (exhaust gas recirculation) valve introduces a small amount of exhaust gas into the intake manifold as a means to reduce emissions. A sensor and a vacuum regulator control the valve and shut it off under wide-open throttle so the engine receives an undiluted mixture.

VSS
The vehicle speed sensor (VSS) sends a signal to the computer and in part controls the operation of the EGR valve. If the VSS is not used, the EFI will function normally, however, the EGR will not; the result will be slightly reduced mileage and some exhaust rumble on sustained deceleration.

Oxygen Sensors
Ford EFI systems use two heated oxygen sensors: one on the left had pipe, one on the right.

Fuel Pump
A pump that can deliver fuel at 40 psi and 33 gph is required. The pump can be in the fuel tank, or the inline type.

Check Engine Light
A small indicator is required to function as a check engine light. It will alert the driver to any malfunction, and can be used to retrieve trouble codes from the computer.

Getting Ready To Run
With all the parts gathered up, you're ready to jump into the Painless instruction manual. Having installed a 302 EFI engine in an F-1 pickup, we can tell you the results will be very satisfying. These engines produce excellent power and remarkable mileage, and the EFI is trouble free. Of course, when we did our installation, we were forced to do it the hard way by cutting up a harness from a donor car. Half a dozen rolls of electrical tape later we had a huge, bulky, and extremely ugly wiring harness. It worked, but it was something we'd never do again, particularly now that there is a Painless way to fuel inject a Ford.