Quick Fuel Technology Qfi Electronic Fuel Injection System User Manual


QUICK FUEL TECHNOLOGY® Qfi™ Electronic Fuel Injection System

Installation and Instruction Manual


Your new Quick Fuel Technology® Qfi™ electronic fuel injection system is one of the industry’s most advanced and flexible EFI packages available. It is designed for V6 and V8 street engines up to 500 cubic inches, and delivering from 250 to 525 horsepower.

Quick Fuel Technology’s Qfi system allows you to use both the handheld controller and a PC laptop to tune the system. The handheld controller is designed to set up the system and to provide the ability to make the majority of tuning changes to suit your engine. The DASHBOARD program on the DVD allows you to use your laptop to make finer adjustments. It will allow you to become more familiar with how the system operates, and is excellent for advanced or tuning professionals to allow the engine to reach its full potential.

It also has the distinct advantage of being compatible with power adder technologies -- nitrous oxide, superchargers and turbochargers, as well as dual throttle body installation. The Qfi throttle body is designed for square flange (4150 and 4500 flange) intake manifolds. Your Qfi throttle body will use a throttle cable linkage designed for square-bore carburetors.

In this Installation/Instruction manual, you will be presented with

The components included with the Qfi system

The required tools to install the system

A list of suggested or required parts for the installation/operation

Instructions for keeping the Qfi system operating at peak efficiency

Please note: The Quick Fuel Technology Qfi electronic fuel injection system is NOT designed for use in the following applications:

Methanol/Ethanol (alcohol) fuel (Exception - E85 fuel)

Diesel engines

Rotary engines

Odd-fire V6 engines

CAUTION: Use of leaded gasoline will shorten the life of the oxygen sensor


Glossary of terms

Below are terms that are frequently used in this installation/instruction manual.

ADAPTIVE LEARNING - This feature utilizes the wide band oxygen sensor in the exhaust downpipe to determine the engine’s real-time air/fuel (A/F) ratio. The Engine Control Unit (ECU) will instantly make the necessary fuel input changes to keep the engine on the desired air/fuel ratio, all the time, and under all conditions. In short, the

“Adaptive Learning” feature is constantly making minor adjustments to maintain the optimum relationship between the fuel and air fed into the engine, allowing it to operate at its highest efficiency for power and/or fuel economy. At the initial start-up, the engine uses the Targeted Air/Fuel Ratio (see below for more details) to control the engine.

CLOSED LOOP - “Closed loop” is the default setting for the ECU, making the "Adaptive Learning" feature functional. To shut off "Adaptive Learning,” the "Closed Loop" feature must be cancelled.

DASHBOARD - This is the laptop software that is on the supplied disc. This provides you with the ability to infinitely tailor your system. It also contains features for advanced tuners.

DATA LOGGING - The Qfi software package can record a wide range of data while driving the vehicle. This allows you to see a timeline of what has occurred during vehicle operation. This feature requires a laptop (not a Mac) to be connected use this function.

ECU - Engine Control Unit. This is the small computer that controls the flow of fuel from the throttle body to the engine.

kPa - The abbreviation for kilopascals, the metric term used to measure vacuum and pressure. You are probably used to seeing "inches of vacuum" and "pounds per square inch" of pressure. Kilopascals are used because the measure terms for vacuum and pressure are the same. The range of 0-100 kPa covers the vacuum part of the scale while 100 and up is the pressure portion of the scale. In other words, a reading of 100 kPa is zero inches of vacuum and zero PSI. The handheld controller software show the kPa reading as the dominant number, but below that, is the conversion to either inches Vacuum or PSI pressure.

MAP - This term describes two different things. For more clarity, we use the lower case for “map” to refer to the program which details or “maps” the engine functions. Upper case "MAP" refers to the term Manifold Absolute Pressure (measured in kPa).

MAP SENSOR - The MAP Sensor provides instantaneous manifold pressure information (in kPa) to the ECU. This is used to calculate the air density, in turn determining the engine's air mass flow rate. This controls, through the ECU, the required fuel metering for optimum combustion.

PULSE WIDTH - Pulse Width refers to the length of time, measured in milliseconds (1/1000 or 0.001 second), the injector nozzle is open and injecting fuel into the airstream. It is controlled by the ECU mounted on the QFI throttle body. While this setting can be changed, it normally is left alone. The “Adaptive Learning” feature controls the pulse width to control the optimum A/F ratio.

SET UP MENU - This is the part of the Dashboard software that allows you to customize the base map for your specific engine. This includes the Volumetric Efficiency (VE) tables.

TARGETED AIR/FUEL RATIO - This is the initial map installed on the computer after answering the set up questions on the hand held controller. This establishes what the computer believes is the ideal air/fuel ratio for the best performance. The "Adaptive Learning" feature of the QFI system modifies the real-time Air/Fuel Ratio (A/F) as the vehicle is driven. This A/F ratio may change at various RPMs or driving conditions. This is a distinct advantage over the carburetor or an EFI system which attempt to run a fixed A/F ratio all of the time.

Volumetric Efficiency (VE) - This refers to the efficiency with which the engine can move the fuel/air charge into and out of the cylinders.



The Quick Fuel Technology Qfi electronic fuel injection system comes from our factory with a handheld controller that allows the user to answer a series of set up questions about the engine and the vehicle, which will produce a basic program for the ECU controller (mounted on the throttle body). See page 18 of this instruction manual for more details. In most circumstances, the information that you will input into the handheld controller will allow you to operate the vehicle.

If there may be a need to fine tune the system’s programming, the installation DASHBOARD DVD software disc packaged with this kit will allow you to manipulate the ECU’s programming. This requires a PC laptop computer with Windows XP, Vista, Windows 7, or Windows 8/8.1 operating system. It will not operate on an Apple MAC laptop.

When you are answering the questions in the Setup window of the handheld controller, you will be allowing the Qfi’s ECU to match your engine’s specifications.

Vented Fuel Tank -- A well-vented fuel tank is REQUIRED for the Qfi system, and a vented fuel cap is NOT sufficient. On page 8, you will see the steps needed to provide an adequate vent, and the need to install a return fuel line.

Air filter clearance -- If you are replacing a square flange carburetor, and there is no hood interference with the current air filter, this filter assembly should not have clearance issues. If you are replacing a Quadrajet or other spread bore carburetor (which requires a square flange adapter), a hood clearance problem might occur. This should be evaluated prior to installation.

Quick Fuel Technology Qfi System Parts List

Please take a moment to review this parts list and the photo to familiarize you with all of the parts included. If a component is missing from the packaging, contact us immediately!

QFT 500 System - BASE KIT -- QFT-500BD

1.Throttle body with injectors (500S (Polished) OR 500BD (Black Diamond))

2.Wide-band O2 sensor

3.ECU wiring harness

4.Throttle body wiring harness

5.O2 sensor bung, gasket, clamps

6.ECU - Engine Control Unit

7.Laptop connector cable

8.QFI Hand Held controller & case

9.Fuel Inlet Kit

10.Data Kit - Qfi Software & Instructions DVD

11.Hardware package -- Fasteners, gaskets, etc.

12.Printed Installation/User manual


QFT 500 System with fuel kit - MASTER KIT -- QFT500BDM

1.All of the above in the QFT 500 Base Kit system

2.Fuel Pressure Regulator

3.Fuel Pressure Gauge

4.Fuel Pump

5.Fuel Filter

6.Fuel Line (high pressure EFI rated) - 15 ft.

7.Fuel line AN fittings

The Qfi fuel pump in the Qfi 500 Master Kit System

includes a 100 micron screen pre-filter built into the pump (It is a white filter you can see just below the threads of the pump’s Inlet fitting), which keeps the coarse particles from reaching the pump.

From your tool box…What tools do you need?

Here is a list of the tools you will need for the installation project. These are basic hand tools you most likely have in your tool box.

Screwdrivers: Straight blade and Phillips head

Wrenches: Open/Closed box-end, Ratchet/Socket set advisable but optional, HEX-head wrench set, Oxygen Sensor wrench

3/8 in. electric drill with assortment of high speed drill bits Hole saw

Soldering gun Solder

Wire Stripper/Crimper

Assorted crimp-style wire ends (open end and loop styles) Electrical shrink wrap tubing

Black electrical tape 14 gauge wire

Medium strength (blue) thread sealer (Loctite 242 or equivalent) Anti-Seize Compound

Required optional parts:

If you have purchased the Qfi 500 System Base Kit (QFT-500BD), these parts are required.

An EFI-rated adjustable pressure regulator (QFT Model 50-5016).

High pressure continuous duty EFI fuel pump -- must be rated to deliver 40-45 psi and 45 gallons per minute (gpm/255 liters/hr - lph). We recommend the Quick Fuel Technology Model 50-5011 pump. (We also recommend a 100 micron pre-filter between the fuel tank and the fuel pump inlet to protect the fuel pump. A sock-type filter in the fuel tank is acceptable. The pre-filter prevents coarse debris from entering the pump and damaging it.) HINT: The higher the filter’s micron number rating, the COARSER the filter.

A 10 micron (or finer) fuel filter between the fuel pump and the Qfi throttle body assembly (QFT Model 50-5015).

A 100 psi fuel pressure gauge (QFT Model 50-5012).


15 ft of 3/8” (0.375” - 9.5 mm)/-06 AN high pressure rated fuel line (reinforced rubber or braided stainless steel)

If engine is equipped with a spread-bore carburetor (such as a Quadrajet, ThermoQuad, Carter AFB or Edelbrock) and you do not wish to change manifolds, an adapter to accept the square flange throttle body is required.

PHASE I: Install the throttle body assembly, plumbing and other mechanical components

Step 1: Preparation & disassembly of fuel system on the engine

Disconnect battery cables. Since you are dealing with the fuel and electrical system in this installation, this step MUST be performed.

o Disconnect plumbing (fuel and vacuum) from the carburetor o Drain the fuel lines into a fuel safe container

o Mark the vacuum lines for relocation on throttle body. On a square bore carburetor (QFT, Holley, Demon), the vacuum lines attach to the same location on the throttle body.

o Remove the carburetor, avoiding tipping the carburetor and spilling fuel o After removal, drain the float bowls into the fuel safe container

o Remove the old carburetor to intake gasket.

If you are replacing a large square flange carburetor (Holley 4500, King Demon), you will need an adapter plate. Use QFT part number 300-4145-1AL.

If replacing a spread-bore carburetor, install an adapter plate to convert to a square flange, installing a new spread bore carburetor gasket below the adapter, and placing a new square flange carburetor gasket on the top of the adapter plate.

Install throttle body to intake (NOTE: This may require new, longer carburetor studs)

o Connect the throttle linkage and the throttle return spring. If replacing a square bore carburetor, the existing throttle linkage/spring assembly can be used. If replacing a spread bore style carburetor, a new assembly must be purchased. (We suggest QFT p/n 49-3 Throttle Return Kit. Available at leading performance retailers)

o Mount with nuts and lock washers (provided), and tighten. DO NOT over tighten.

Remove the old temperature sensor and install the provided 3/8-NPT Coolant Temperature Sensor into the intake manifold coolant port, as close as possible to the thermostat. (This may require a reducer bushing.)

o Connect the Green/Black wiring harness

from the throttle body to the coolant temperature sensor.

See Service Parts list on page 30 should the temperature sensor require replacement in the future.


Install the vacuum lines

o ALWAYS use new vacuum line and replace each hose, one at a time

o Measure each old hose and cut new hose to that length and install to the proper port on the throttle body and the vacuum source used by the carburetor

o Repeat for each hose

o Dispose of the old vacuum lines

o Connect the power brake (if equipped) vacuum line to the large 3/8-inch vacuum port on the rear base of the throttle body.

If the vehicle requires vacuum for the transmission modulator, connect to this port as well.

If both a power brake unit and a transmission modulator is used, install a vacuum T- connector to accommodate the vacuum lines

If you are using a vacuum advance distributor, connect distributor vacuum line to either the upper (timed) port on rear or on the right side of the throttle body

oConnect the MAP sensor, located on the bottom of the QFI ECU box, to the lower port on the rear of the throttle body. (QFT does not recommend putting a tee in this line for any other vacuum use.)

oIMPORTANT Be certain to cap all unused vacuum nipples, using the caps which were installed on the throttle body

Step 2: Install the Oxygen sensor

If no previous oxygen sensor was used, locate a suitable location to install the supplied oxygen sensor bung. Install in a position where the sensor can be easily serviced, if necessary. The sensor must be placed 20 inches or more away from the cylinder head for proper operation.

If a catalytic converter is on the vehicle, place the oxygen sensor BETWEEN the engine and the converter


For stock, cast iron manifolds, the location should be just past where the exhaust pipe connects to the exhaust manifold.

If headers are used, make sure it is about 4-6 inches past the collector pipe o Install to the exhaust pipe (not into a header tube or the collectors

VERY IMPORTANT On both stock manifolds and headers, the sensor should be mounted between the 9 and 3 o’clock position and at least 10° above horizontal (wire side up, sensor tip down). This prevents condensation, exhaust debris from collecting in the sensor and contaminating it, as well as possible road damage. Again, always think about placing the sensor where it can be serviced the most easily.

Drill a 5/8-inch hole in the exhaust pipe

Using stainless steel worm gear clamps OR weld (PREFERRED) the bung in place on the exhaust downpipe (This may require installation at a welding or muffler shop)

Using an O2 sensor installation wrench, install the oxygen sensor in the bung. Carefully apply antiseize compound to the threads before installing, be certain to apply ONLY to the threads, not to the sensor.

Plug the harness cable from the throttle body into the cable from the Oxygen Sensor. Using cable ties, keep harness away from the exhaust system and/or moving parts.

See Service Parts list on page 30 should the Oxygen sensor require replacement in the future.


Quick Fuel Technology Qfi Electronic Fuel Injection System User Manual

Step 3: Install the fuel system

Review the diagrams below to understand the installation of the major components of the fuel delivery system. There are two correct ways to install the pressure regulator -- in front of the Qfi throttle body (or) after it. (OPTION 1 is the installation shown on page 11).

The installation of the fuel system starts with the fuel tank.

Drain the fuel tank and remove it according the vehicle maker’s instructions. NOTE -- ALL fuel tank work MUST be done with a dry tank, with no fumes in the tank! Any fuel tank welding should be done by a professional welder!!

Clean the interior of the tank, since debris in the fuel is an enemy of any EFI system


If not present, install a free-flowing vent in top of tank (REQUIRED). The vent should be a MINIMUM of a ¼-in. (0.250 in/6 mm) diameter. A vented filler cap is not adequate for this system.

o The vent tube should have no kinks, with the opening pointed to the top of the tank (upside down “U”) to minimize debris from entering the tank.

Install return fuel line (REQUIRED) to top

of fuel tank (may require placing a hole in the top of the tank to install bung). o Use a barbed-style fuel line fitting

o Route the return line to top of the engine

o This line is a low pressure line, and needs only standard 3/8 in. (0.375 in./10 mm) fuel line

o This line should be securely fastened (with no slack in the line), keep line away from heat source (or shielded if not possible) and fasten securely to chassis next to the floor pan.

o Attach securely with a worm-gear or spring style hose clamp at each end

Step 4: Installing the Fuel Pump and filter


Install a sock (or) screen type pre-filter in the gas tank. It will be adequate to capture any large debris that can damage the fuel pump.

The other option is an in-line 100 micron pre-filter between the tank and pump


The fuel pump has a 100 micron pre-filter built into the pump (It is a white filter you can see just below the pump’s Inlet fitting). This can be cleaned by back flushing -- removing the pump and pouring fuel through the pump from the outlet end of the pump.

Begin by installing a 3/8 in. (0.375 in. /9.5 mm) barbed fuel line fitting in the fuel tank outlet.

If the tank’s fuel outlet is less than 3/8 in. (many fuel tanks for carbureted applications will have

5/16 in. outlet), you must a install a 3/8 in. bung (If using braided steel line, a 3/8” NPT/-6 AN adapter fitting must be used)

Check to be certain the fuel line from the tank will be ABOVE the fuel pump inlet port


Reinstall the fuel tank. Be certain it is securely mounted to the chassis

Mount fuel pump to the chassis, using the two mounting brackets with rubber vibration isolators provided.

o If using the QFT 500 System Base Kit, you must use an EFI pump (either in-tank or external) rated for 40-45 psi (continuous) and 45 gallons per minute (gpm).

o Mount below the bottom of the tank outlet for a gravity feed

o Position within 2-3 ft. (61-91 cm) of the tank

o Place in protected position above the lowest portion of the frame and away from the exhaust (or shielded from exhaust heat. This is also necessary for fuel line routing)

o If frame mounting is not possible, fabricate an “L” shaped metal bracket, and mount close to tank, and position the pump at or below the fuel tank outlet.

o Remove the plugs from the pump and install the 3/8 in. (0.375 in. /10 mm) fittings (provided) with blue thread locker sealer (Loctite 242 or equivalent). DO NOT use Teflon tape or pipe dope on fuel lines -- will clog fuel injectors!!

o Install the sealing washer on the outlet fitting and attach to the outlet of the pump o If using AN fittings, use 3/8” NPT/-6 AN adapter fittings at both ends of the fuel pump


Install fuel pump ground line to the chassis.

o Drill 5/32 in. (0.15625 in/4 mm) hole in chassis

o Scrape area to expose bare metal (assures an excellent ground) o Install with 3/16 in. (0.1875 in/4 mm) self-tapping metal screw

inserted through ring lug

Attach the power (hot) lead to the fuel pump. Use of electrical shrink wrap over the pump’s electrical terminals after installing is

highly recommended. This helps protect the pump terminals on the hot and ground sides from corrosion.

Install inline filter(s) -- pre-pump (low pressure) is recommended/high pressure filter required (NOTE: A carburetor filter CANNOT be used)

o In-line Pre-Filter (OPTIONAL) -- If choosing to use an inline fuel pre-filter (in addition to, or instead of, a sock-type in-tank filter) between the fuel tank and the fuel pump, mount it securely to the chassis. This MUST be a lowrestriction filter (100 microns). It must be mounted in line with the fuel pump inlet (or higher but NEVER lower), and

should be able to maintain gravity feed to the pump. (Incorrect filters can cause the pump to create a vacuum and aerate, leading to reduced fuel delivery to the injectors and poor engine performance.)


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