FST PRO FUEL SYSTEM TESTER MODEL MV5545 USER’S MANUAL Have a technical question? If you have questions, or require technical service, please contact our trained service technicians at: 1-314-679-4200 ext. 4782 Monday – Friday 7:30 am to 4:15 pm CST Visit our website at www.mityvac.com for new products, catalogs, and instructions for product use. Need service parts? To order replacement or service parts, visit us online at www.mityvacparts.com or call toll free 1-800-992-9898.
Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Components, Service Parts, and Accessories . . . . . . . . . . . . . . . . . . . 3 Standard Kit Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction • The Mityvac FST Pro Fuel System Tester is an advanced diagnostic tool designed for troubleshooting and pinpointing common automotive fuel delivery system malfunctions, including: • • Failing fuel pump • Faulty pressure regulator • Blocked inline filter • Blocked inlet strainer/sock • Pinched or crushed fuel line • Fuel contamination • Fuel tank vortex • Fuel system leaks This manual focuses on the application of the FST to modern electronic fuel injection (EFI) systems.
Standard Kit Components Part Number Description 824141 High Pressure Gauge 824149 Pressure Relief Hose (1/8"/3mm ID x 6'/1.8 m long) 824148 Bypass Hose (1/4"/6.5 mm ID x 6'/1.8 m long) 824144 Scissor Hose Clamps (Qty 2) 824147 Flowmeter Hose (3/8"/9.5 mm ID x 4'/1.
Service Parts 2 3 Part Number Description 1 824182 Flow Tube Shield 2 824177 Male Quick-Connect Fitting 3 824176 Bypass Port 4 824175 Flow Control Valve Knob 5 824174 Flowmeter Inlet/Outlet Connector (Qty 2) 7 7 6 824146 Flow Control Valve 7 824145 Flowmeter Seal Kit 824183 Wing-Style Hose Clamp (Qty 4) 824181 Flowmeter Boot 824180 Adapter O-Ring Kit 824178 Ford Springlok Tether with Clip 1 10 824182 824181 824180 4 6 824178 824177 824176 7 7 824175 824174 82414
Fuel System Test Adapters Description Applications Order No. Reference No. GM/Chrysler Right Angle Test Port Adapter GM & some Chrysler vehicles with 7⁄16" x 20 thread test port on fuel rail MVA507** 20 Ford/Chrysler Right Angle Test Port Adapter Ford & some Chrysler vehicles with .
Fuel System Test Adapters Description Applications M16 x 1.5 Ball Nose Adapter European vehicles with CIS fuel system Order No. Reference No. 11A MVA519 11B 3A M16 x 1.5 Adapter GM Vortec MVA520 3B 4A M14 x 1.
Assembly For flexibility and ease of storage, the FST Pro features a modular design that is quick to assemble and breakdown. Proper assembly for testing is covered in the Setup and Installation instructions Bypass Hose Prior to the first use of the FST, the 1/4" (6.5 mm) ID clear bypass hose should be assembled to the bypass port extending from the side of the flowmeter, above the flow control valve. To connect the fuel bypass hose: 1.
To release the connection, press and hold the release button on the side of the female quick-connect, while pulling the connection apart (Fig. 8). Do not attempt to release the quick-connect connection using a disconnect tool, as this may damage the fitting. Replacement clips are included if needed Adapters The FST Pro includes a selection of adapters for connecting inline with the fuel delivery systems of a wide range of automotive makes and models.
Flex Hose Connections In many cases it is convenient to connect the FST Pro into the fuel delivery system at a location where a flexible rubber hose is secured to a steel fuel line using a screw clamp. A special adapter set is included with the FST Pro for installing it into this type of connection. It includes a universal barb adapter, three flexible hose adapters (1/4", 5/16", 3/8"), and four wing screw clamps. To install the flex hose adapters: 1.
Principle of Operation Fuel Delivery Basics Modern fuel injected engines rely on precision fuel delivery to perform at peak output and efficiency. It is the function of the fuel delivery system to ensure that proper fuel pressure and volume are present in the fuel rail to meet the demands of the engine under varying operating conditions.
In regards to return fuel systems, knowing the pressure and flow at idle is a very good indication as to whether the fuel system is functioning properly. However, while pressure can be compared to a manufacturer’s spec, idle flow is not typically documented. Most return fuel systems will flow around .5 gallons (2 liters) per minute at idle. However, the idle flow may range from .3 to .7 GPM (1.1 to 2.6 LPM) depending on the vehicle make, model, year and engine. Under a heavy load, a 5.
When the valve is rotated to the BYPASS position pointing up, fuel is routed through the bypass port located on the side of the flowmeter just above the flow control valve (Fig. 20). Bypassing eliminates all restriction to the flow, and the maximum volume output of the pump is indicated on the flowmeter. Fuel pressure will drop to zero. This is termed the Peak Flow Test, and is applicable to return and returnless systems.
Types of Fuel Delivery Systems For the purpose of accurately applying and testing with the FST Pro, today’s fuel delivery systems can be divided into three typical configurations: • • • Return (Bypass) Fuel Systems Returnless Fuel Systems – Mechanically Regulated Returnless Fuel Systems – Electronically Regulated The fundamental differences between return and returnless fuel systems affect the values for pressure and flow displayed by the FST, and influence its diagnostic capabilities.
Returnless fuel systems (mechanically regulated) were pioneered by Chrysler in the mid-90s. Since that date, other car manufacturers have been implementing returnless systems onto their cars. Now returnless systems are common on most all new cars and light trucks. Mechanically Regulated In the case of mechanically regulated returnless systems, the term “returnless” can be misleading. Like a return system, the fuel pump operates continuously, producing an uncontrolled output.
Electronically Regulated Fuel Filter Fuel Supply Line Ford began developing an electronically regulated returnless fuel Pressure Test Port delivery system in the late nineties, and began implementing it on their cars in the early to mid-2000s. This system shares some of the Fuel Rail features and benefits of both return and returnless systems, but with the addition of advanced control technology.
Fuel System Components peak capability of the pump. The manufacturer’s service manual should document this in their fuel system diagnostic procedure. The modern fuel delivery system is comprised of several critical components. A malfunction of one or more of these can cause the system to fail or under perform. The function of the FST is to diagnose when a fuel system failure has occurred, and to pinpoint the component(s) which caused the failure.
A clogged inlet strainer can starve the fuel pump of fuel, causing it to cavitate. Cavitation will create rapid changes in fuel density, causing the float in the FST flowmeter to bounce up and down. It can also cause the needle on the pressure gauge to bounce. In addition, as the pump tries to pull gas through the clogged strainer, it creates a pressure drop that may cause air bubbles to form and become visible. high.
Setup and Installation Determining Where to Install the FST Inline Connection Regardless of the type of fuel delivery system, the FST Pro is most effective at diagnosing malfunctions when connected inline with the flow of fuel. The initial installation should be made at an access point along the fuel supply line, as close as possible to the fuel rail (Figs. 28, 29 and 30). At this location, the fuel pressure and flow measured by the tester will most accurately represent the conditions within the fuel rail.
reduce fuel spillage, whenever possible, try to select the required adapters before disconnecting the fuel line, and have them ready to install. Setting-up the FST Pro Once the installation point has been determined, follow the instructions below to setup the tester prior to disconnecting the fuel line. 1. Place the vehicle transmission in park or neutral, apply the parking brake, and turn the key off. 2. Hang the pressure gauge under the vehicle hood or other appropriate location. 3.
7. Connect the hose extending from the flowmeter connection labeled “IN”, to the other end of the adapter (Fig. 36). 8. Install the second FST connection adapter to the fuel line running to the fuel rail. If the fuel line connection used by the vehicle manufacturer is a 3/8” quick-connect style (SAE J2044), a second adapter is not required. 9.
Testing and Diagnostics Testing and diagnostic procedures vary depending on the type of fuel delivery system. Prior to testing, the fuel delivery system must be identified as Return, Returnless (mechanically regulated) or Returnless (electronically regulated). For detailed information on fuel delivery systems and how to identify them, refer to the section entitled Types of Fuel Delivery Systems, earlier in this manual.
At idle, the volume of fuel flowing through the tester should remain steady between 0.3 and 0.6 gallons per minute (GPM) or 1.1 and 2.2 liters per minute (LPM). 6. Noting the values for pressure and volume, if either is out of range, these are indications of a problem with one or more components of the fuel system. However, performing the Pressure and Flow Demand Tests below, is required to reach a more accurate diagnosis, and to pinpoint the cause of a malfunction. Pressure Demand (Dead-head) Test 7.
continues to experience symptoms of a fuel delivery malfunction, it could be caused by contaminated fuel, faulty fuel injector(s), or an intermittent component malfunction such as a sticking pressure regulator or loose electrical connection. Follow the vehicle manufacturer’s recommended procedures for the inspection and repair of these components.
Under-restricting Fuel Pressure Regulator An under-restricting pressure regulator will cause the idle pressure in Zones 1 and 2 to drop below spec, and the idle flow to be higher than normal. If this is what the FST is indicating, and the peak pressure and flow are normal, then the cause is most certainly the pressure regulator. If the fuel pressure regulator is vacuum modulated (see Fuel System Components/Pressure Regulator), it is possible to check if it is sticking by disconnecting the vacuum line.
Returnless Fuel Delivery Systems (Mechanically Regulated) At this point, it is assumed that the FST has been properly installed inline with the fuel delivery system as recommended, and that it has been primed to ensure no leaks are present (See FST Pro Setup and Installation). The following procedure will ensure the most effective diagnostic use of the FST: Test Procedure Operational Test 1.
OPEN position. Peak Demand Test 7. Note the vehicle’s engine size and maximum engine speed (RPM). Refer to the Maximum Engine Fuel Volume Requirements table (Appendix A), and use the size and speed values to determine the maximum fuel volume requirement of the engine. 8. With the car idling, rotate the flow control valve past the 90° CLOSED position towards BYPASS (Fig. 48).
A clogged inlet strainer can cause the fuel pump to cavitate because it is starved for fuel. Cavitation will create rapid changes in fuel density, causing the float in the FST flowmeter to bounce up and down during the peak flow and/or capability test. It can also cause the needle on the pressure gauge to bounce. In addition, as the pump tries to pull gas through the clogged strainer, it creates a pressure drop that may cause air bubbles to form and become visible.
After connecting the FST, it is normal to have air trapped in the fuel lines and flowmeter. Cycling the ignition switch (or cranking the engine briefly) with the flow control valve in the BYPASS position can help purge air from the system. Once fuel fills the flowmeter and flows through the bypass hose, return the valve to the OPEN position. The bypass hose must be routed and secured into an approved fuel container before operating the flow control valve in BYPASS mode.
9. With the car idling, rotate the flow control valve past the 90° CLOSED position towards BYPASS (Fig. 54). Adjust the valve until the flowmeter indicates an amount of fuel flow equivalent to the value for the maximum engine fuel volume taken from the table (Fig. 55). 10. Note the pressure reading on the gauge. 11. After noting the capability pressure, return the flow control valve to the OPEN position. Testing is complete.
ty, causing the float in the FST flowmeter to bounce up and down during the peak flow and/or capability test. It can also cause the needle on the pressure gauge to bounce. In addition, as the pump tries to pull gas through the clogged strainer, it creates a pressure drop that may cause air bubbles to form and become visible. These indications of a clogged inlet strainer may or may not be evident during testing.
5. Turn off the engine and immediately clamp off the FST inlet hose running to the tester from the fuel supply line. This will trap the pressure gauge between the clamp, the fuel rail, the pressure regulator, and the fuel return line. 6. If the pressure drops, either the injectors or the pressure regulator is leaking. 7. With the second scissor clamp, pinch off the fuel return line between the pressure regulator and the fuel tank. 8. If the pressure continues to drop, the cause is a leaking injector(s).
the hose is clamped, quickly disconnect the hose from the fuel system before the pressure has time to build. Try to keep a shop towel wrapped around the connection to catch any fuel spray. 4. Rotate the flow control valve to the CLOSED position to help prevent fuel leakage. 5. With the scissor clamps locked in place on the connecting hoses, disconnect the FST adapters and fitting connectors from the vehicle’s fuel system (Fig. 58). 6.
Appendix A Maximum Engine Fuel Volume Requirements (Gallons/Minute) liters Engine Size CID 3000 4000 Engine Speed (RPM) 5000 6000 7000 8000 1.0 61 0.05 0.06 0.07 0.09 0.10 0.12 1.2 73 0.06 0.07 0.09 0.11 0.12 0.14 1.4 85 0.06 0.08 0.10 0.12 0.15 0.17 1.6 98 0.07 0.10 0.12 0.14 0.17 0.19 1.8 110 0.08 0.11 0.13 0.16 0.19 0.21 2.0 122 0.09 0.12 0.15 0.18 0.21 0.24 2.2 134 0.10 0.13 0.16 0.20 0.23 0.26 2.4 146 0.11 0.14 0.18 0.21 0.25 0.
Appendix A Maximum Engine Fuel Volume Requirements (Liters/Minute) liters Engine Size CID 3000 4000 Engine Speed (RPM) 5000 6000 7000 8000 1.0 61 0.19 0.23 0.26 0.34 0.38 0.45 1.2 73 0.23 0.26 0.34 0.42 0.45 0.53 1.4 85 0.23 0.30 0.38 0.45 0.57 0.64 1.6 98 0.26 0.38 0.45 0.53 0.64 0.72 1.8 110 0.30 0.42 0.49 0.61 0.72 0.79 2.0 122 0.34 0.45 0.57 0.68 0.79 0.91 2.2 134 0.38 0.49 0.61 0.76 0.87 0.98 2.4 146 0.42 0.53 0.68 0.79 0.95 1.
Appendix B – Return Fuel System Diagnostic Guide Results Idle Scenario Pressure Idle Flow Peak Pressure Peak Flow Normal Greater than maximum fuel volume requirement* Normal 50% to 100% higher than spec Normal Normal 50% to 100% higher than spec Low Potential Causes .7 to 1.0 GPM Fuel system is operat(2.5 to 4.0 LPM) ing normally 1 Normal 2 Normal to slightly low Low Less than maximum fuel volume requirement* 3 Low High Greater than .7 GPM (2.
Appendix B Return Fuel System Diagnostic Guide Scenario 2 Diagnosis: A restriction to the supply of fuel to the engine such as a clogged inlet strainer, inline filter, or pinched fuel supply line will reduce the flow of fuel. However, pressure will remain normal or drop only 1 or 2 psi below spec. If the flow at idle is less than the calculated maximum fuel volume requirement, then the engine will be starved of fuel in a heavy-load condition such as wide-open throttle.
Appendix C – Returnless (mechanically regulated) Fuel System Diagnostic Guide Results Scenario Idle Pressure 1 Normal Normal 2 Normal Low Peak Flow .7 to 1.0 GPM (2.5 to 4.0 LPM) Less than .7 GPM (2.5 LPM) 3 Low Normal .7 to 1.0 GPM (2.5 to 4.0 LPM) 4 High Normal .7 to 1.0 GPM (2.5 to 4.0 LPM) 5 Low Low Peak Demand Pressure Less than .7 GPM (2.
Appendix C Returnless (Mechanically Regulated) Fuel System Diagnostic Guide Scenario 2 Diagnosis: A restriction to the supply of fuel to the engine such as a clogged inlet screen, inline filter, or pinched fuel supply line will reduce the flow of fuel. This will be evident by the reduction in peak flow. Idle pressure will remain normal or drop only 1 or 2 psi below spec. Capability pressure will be low, depending on the amount of restriction and the type of return/filtration method used.
Appendix D – Returnless (Electronically Regulated) Fuel System Diagnostic Guide Results Idle Peak Demand Pressure Scenario Pressure Peak Pressure Peak Flow Potential Causes 1 Normal Normal Less than 10% below idle pressure Normal 50% to 100% higher than spec Normal 2 Normal Low Greater than 10% below idle pressure Normal 50% to 100% higher than spec Low Less than .7 GPM (2.5 LPM) 3 Low Low Greater than 10% below idle pressure Low 50% to 100% higher than spec Normal .7 to 1.
Appendix D Returnless (Electronically Regulated) Fuel System Diagnostic Guide Scenario 2 Diagnosis: A restriction to the supply of fuel to the engine such as a clogged inlet strainer, inline filter, or pinched fuel supply line will reduce the flow of fuel. However, idle and peak pressure will remain normal or drop only 1 or 2 psi below manufacturer’s specification.
Lincoln Industrial Standard Warranty LIMITED WARRANTY Lincoln warrants the equipment manufactured and supplied by Lincoln to be free from defects in material and workmanship for a period of one (1) year following the date of purchase, excluding therefrom any special, extended, or limited warranty published by Lincoln. If equipment is determined to be defective during this warranty period, it will be repaired or replaced, within Lincoln’s sole discretion, without charge.
