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How to Fix a Fuel Pump?

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What is a fuel pump? Where is a fuel pump located? What causes a fuel pump to go bad? How do you diagnose a fuel pump? How to fix a fuel pump? Where to get a fuel pump replacement? All these fuel …

What is a fuel pump? Where is a fuel pump located? What causes a fuel pump to go bad? How do you diagnose a fuel pump? How to fix a fuel pump? Where to get a fuel pump replacement? All these fuel pump questions answered, plus much more. If you want to discover more about auto parts, checkout the rest of the presentations from Buy Auto Parts, or visit www.buyautoparts.com

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  • 1. How To Fix a Fuel Pump? What is a Fuel Pump? What Causes a Fuel Pump to Break? How to Diagnose and Fuel Pump? And, How to Fix or Replace a Fuel Pump?source: http://www.buyautoparts.com/howto/repair-fuel-pump-parts.htm
  • 2. Fuel Pump Diagram source:http://www.buyautoparts.com/howto/wha t-is-a-fuel-pump.htm
  • 3. What is a Fuel Pump?• The fuel pump is the unit in a vehicle which pushes fuel from the tank to the motor. The unit usually sits in the tank of the vehicle using an electric powered motor consisting of an array of valves and spring that work in conjunction to create suction from the unit.• This suction draws fuel into the pump and then the return spring will push the fuel up into the lines creating pressure.• The fuel pressure in the lines is not regulated by the pump itself, the pump will just pump to its maximum ability with the voltage provided from the vehicle.• The fuel pressure is regulated down the fuel lines at the motor by a fuel pressure regulator also known as a FPR. The higher the voltage to the pump the faster the pump will move and the higher the flow of fuel will be from the pump.• Generally a fuel pump will be part of an assembly which will also include the sending unit, level arm and screen filter. source: http://www.buyautoparts.com/howto/what-is-a-fuel-pump.htm
  • 4. Fuel PumpAssembly Layout source:http://www.buyautoparts.com/howto /fuel-pump-assembly-layout.htm
  • 5. Fuel Pump Assembly Layout• Fuel pump assemblies are not very complex units in most applications, they consist of a few key parts that perform essential functions.• Let us start at the bottom of the unit and work our way up, – The filter screen is at the bottom and this is there to catch large debris that may be in the tank itself. The screen filter is not a replacement for the fuel filter which is recommended to be replaced when the pump is replaced. – The fuel pump itself is the unit that will pull the fuel from the tank and push it into the fuel lines and eventually to the motor. – Then there is the level sender unit which houses the float which calculates the amount of fuel in the tank and sends the readings to the fuel gauge on the dash of the car. – Finally on the very top of the unit there is the hose assembly which is where the fuel lines hook up to the assembly and flow the fuel to and from the engine. source: http://www.buyautoparts.com/howto/fuel-pump-assembly-layout.htm
  • 6. Fuel System LayoutThere are different fuel system layouts for may different fuel systemconfigurations, In-tank pump, Semi in- tank, Pump set or in-tank pump connected to sucking jet pump. source:http://www.buyautoparts.com/howto /fuel-system-layouts.htm
  • 7. Fuel System Introduction source:http://www.buyautoparts.com/howto /fuel-system-introduction.htm
  • 8. Engine ComponentsRelated to the Fuel Systemsource: http://www.buyautoparts.com/howto/engine-components-related-to-the-fuel- system.htm
  • 9. Fuel Pump Wiring Guide 1 REPLACING CHASSIS ELETRICAL CONNECTOR Refer to the vehicle service manual or equivalent to remove the fuel module assembly. Remove 12 inches (330mm) of tape and lack plastic conduit from the vehicle body harness and examine the wiring for number, color and gauge size. If the vehicle body harness wiring colors and sizes are not identical to the new GT280 electrical connector wiring, review the wiring diagrams below and determine which combination matches your vehicle application. General Rule - a pump which has grey, purple, black, and black wires. The problem usually is with the 2 black wires and an OEM could have many other colors. The key is the gauge of the 2 black wires. One is thicker, no matter what the color, match the thicker gauge with the thicker one and thinner gauge with thinner wire. Small gauge/diameter - ground wire for sending unit Thicker guage/diameter - ground wire for pump source:http://www.buyautoparts.com/howt o/engine-components-related-to- the-fuel-system.htm
  • 10. Fuel Pump Wiring Guide 2 If the vehicle body harness wiring does not match any of the combinations show above, refer to the wiring identification diagram and the vehicle service manual or equivalent to determine the correct wiring alignment for the new GT280 Electrical connector. INSTALLING THE NEW CHASSIS CONNECTOR: To assist in maintaining the approximate length of the vehicle body harness, tape the new GT280 electrical connector to the Metri-Pack 150 connector in the vehicle body harness. General Rule - a pump which has grey, purple, black, and black wires. The problem usually is with the 2 black wires and an OEM could have many other colors. The key is the gauge of the 2 black wires. One is thicker, no matter what the color, match the thicker gauge with the thicker one and thinner gauge with thinner wire. Small gauge/diameter - ground wire for sending unit TThicker guage/diameter - ground wire for pump source:http://www.buyautoparts.com/howt o/engine-components-related-to- the-fuel-system.htm
  • 11. Fuel Pump Wiring Guide 3 Align each wire on the GT280 Connector with the correct wire on the body harness and cut the wires at the desired location for the wire splice. Cut the first pair of wires 2 inches (50mm) away from the taped electrical connectors and stagger each cut 1.5 inches after that. Remove the tape and discard the original body harness electrical connector. Remove approximately 5/16 inch of wire insulation from each of the leads on the new GT280 connector. Now connect the GT280 Connector to the body connector on the vehicle. Crimp the spiced wires into place and shrink the wrap onto the wires with a heat gun. Now re-add the black plastic conduit and re-tape as before. General Rule - a pump which has grey, purple, black, and black wires. The problem usually is with the 2 black wires and an OEM could have many other colors. The key is the gauge of the 2 black wires. One is thicker, no matter what the color, match the thicker gauge with the thicker one and thinner gauge with thinner wire. Small gauge/diameter - ground wire for sending unit Thicker guage/diameter - ground wire for pump source:http://www.buyautoparts.com/howt o/engine-components-related-to- the-fuel-system.htm
  • 12. Why Fuel Pumps Fail?We all know that just replacing an electric fuel pump won’t solve a no-fuel complaint because the pump itself isonly part of the fuel delivery system. A good technician must diagnose the no-fuel problem in order to properlyservice the vehicle. Here are a few of the most common reasons an electric fuel pump fails:• Loss of current or low voltage – The pump can’t run without electricity, so anything that prevents current or voltage from reaching the pump will make it stop. This includes corroded, loose or broken wiring.• Dirt – Sediment or other debris in the tank can clog the pickup strainer, accelerate pump wear, damage the pump and/or cause the pump’s check valve to stick open (which can cause a hard-starting condition due to loss of pressure when the engine is shut off). When dirt has caused a pump failure or if there appears to be a lot of dirt or sediment in the tank, the tank should be thoroughly cleaned to prevent a repeat failure.• Rust - Corrosion inside the tank produces rust, which can flake off and plug up the pickup strainer and have the same damaging effects on the pump as dirt. Rust is caused by condensation, which occurs during cool, humid weather when the fuel tank is low. Keeping the tank full will minimize the formation of condensation. If the tank is badly rusted or leaking, it should also be replaced.• Normal wear – Most pumps are designed for long term durability and performance, but their lifespan depends on lubrication and cooling provided by the fuel itself. Frequent driving with a low fuel level may occasionally starve the pump for lubrications and cooling, which can lead to accelerated wear or even pump damage.• Failure signs – Noise may sometimes be an indication of excessive pump wear. Some pumps are inherently noisier than others, often because of the way in which they’re mounted inside the tank. Noise can also be caused by a loose or missing rubber noise insulator around the pump, or physical contact with the bottom of the tank baffles. source: http://www.buyautoparts.com/howto/repair-fuel-pump-5.htm
  • 13. Common Causes of Fuel Pump Failure• Fuel pump pressure in most imports and later model domestics is relative to engine speed and this can lead to misdiagnosis of issues with the fuel pump assembly. When the engine RPM is higher the fuel pressure must be increased to keep up with the demand to protect from running lean. The vehicle PCM may shut off the fuel pump after ignition if both the crank speed sensor and ignition triggering signals are not present.• Cold weather starting is an issue that plagues owners in the winter months and these issues are all related to the electric current from the battery. Cold temperature leads to lower voltage from the battery which will cause the fuel pump to struggle creating pressure in the system. The less voltage from the motor the slower the pump will spin, this can cause starting issues due to low pressure.• The air flow sensor can also create false symptoms of fuel pump failure since the two systems are so closely linked. When the throttle plate sensor is not reading correctly the vehicle will not active the fuel pump during cranking. The sensor system in a car is one of the main sources for misdiagnosis. source: http://www.buyautoparts.com/howto/repair-fuel-pump-3.htm
  • 14. Common Misdiagnosis Factors for Fuel Pump Assemblies• Determining fuel pump issues is one of the most difficult areas of a vehicles ignition system to diagnose. The systems in newer cars are now controlled by the vehicle ECU and can give false signals. Many repair shops have begun to receive a number of the fuel pump assembly units returned as defective after they are installed due to misdiagnosis.• Some the systems that control the fuel pump might be surprising to even the most seasoned mechanic. Nowadays some auto makers go so far as to have systems like the crank shaft sensor control the fuel pump assembly in order to protect the engine in case of failure or accident.• Another large issue that many shops deal with is the level sender not working correctly on newly installed fuel pump units. The level sending is a very sensitive part of the fuel pump assembly, sometimes the unit may not read right simply because of dented tank. The fuel pump assembly level sender can take up to an hour to calibrate and will give false readings if the unit is not properly calibrated in the tank on level ground.• The electrical system can play havoc on the fuel pump as well, a lot of newer cars require a signal from the dash to correctly calibrate the level. If the dash is not working sometimes the car wont even run the signal must be complete for the computer to allow the fuel pump to send pressure. It is easy to assume that the fuel pump is the problem but be sure all the issues are fully inspected before replacing with a new unit. source: http://www.buyautoparts.com/howto/repair-fuel-pump-2.htm
  • 15. Fuel Gauge Issue Diagnosis• This process can be applied to all recent GM cars except those with computerized gauges.• 1) Locate the fuel sender feed wire near the fuel tank. Youre looking for a single tan colored wire. With the tan wire disconnected at the fuel tank, the fuel gauge should read past full with the ignition on. Wait a few moments as some fuel gauges take a long time to respond. Touch the tan wire from the body to any convenient ground and the gauge should read empty. If not, you have a wiring problem or a bad gauge.• 2) If the gauge responds correctly, the gauge and wiring are OK. Next use a multi-meter to measure resistance to ground of the sender wire connection on the fuel sender on the top of the fuel tank. Measurements should track the fuel in tank.• Full-84-88 ohms• Half- 40 ohms, give or take• Empty - 0-2 ohms• If this doesnt check, then sender or wiring on top of the tank is bad or the sender not adequately grounded. Senders are typically grounded by a black wire which is welded to the sender and attached to the body with a sheet metal screw.• 3) If the sender checks OK but gauge and wiring dont, clean the connections, reconnect the sender wiring and separate the gauge should then read past full. Ground the tan wire in the dash side of the Fisher connector and the gauge should read empty. If not, you probably have a bad gauge or possibly a dash wiring problem. Go to Step 5.• 4) If the gauge checks OK, then make the same resistance checks to the tan wire in the body side of the Fisher connector. If the readings are different than those at the sender, body wiring has a problem and requires a detailed inspection. If they look OK, then the Fisher connector is probably dirty.• 5) Clean and reconnect Fisher connector, poll the connector off the back of the gauge and make the same resistance checks to the tan wire. If they dont check, yon have a dash wiring problem. If they check OK, your gauge is bad. Gauges can be bench-checked but this is best left to a specialist. source: http://www.buyautoparts.com/howto/fuel-gauge-problem-diagnosis.htm
  • 16. How To Check for a Faulty Fuel Pump?The fuel pump diagnostic process may seem like a long and overlycomplicated one but if the proper steps are not followed it can lead to aneven bigger headache. The four major fuel pump assembly failure symptomsand what the issues could be;• 1. A dead fuel pump (could be the pump, relay or wiring circuit)• 2. A plugged or clogged filter• 3. Low fuel pressure (weak pump or partially blocked line)• 4. No signal to the injectors (bad injector relay or driver circuit)• There are a number of tests that can be run to check the pressure being created by the fuel pump assembly to narrow the issue search. The dead head test is used to check the pumps ability to create high fuel pressure and the fuel volume test checks the units flow. Both fuel pump tests are to check that the pump is working and will make pressure in different situations. *Note: be sure there are no open flames or sparks anywhere near the test area. source: http://www.buyautoparts.com/howto/repair-fuel-pump-4.htm
  • 17. The 9 Factors to Consider in Fuel System Diagnostics• A faulty fuel pump may not be the only failure that your car is facing when having a fuel issue. The fuel pump assembly may be only part of a larger issue, check for other causes to be sure you are not replacing the wrong part. There are 9 factors to consider when a fuel system issue hits your car. 1. The first is the fuel cap, the system cannot pump fuel correctly without the proper seal from the filler cap. 2. Contamination in the fuel tank can also be the cause of fuel system failure by clogging lines or building up on the pump 3. The supply and return lines may be clogged with debris and will need to be cleaned before proper operation can resume. 4. The fuel pressure regulator needs to be changed each time there is a fuel system servicing done this will keep the system running smoothly. 5. Wiring in the fuel system can also be faulty and should always be checked for melted, worn or loose connectors. source: http://www.buyautoparts.com/howto/repair-fuel-pump.htm
  • 18. The 9 Factors to Consider in Fuel System Diagnostics cont…6. The fuel pump strainer is the first line of defense for the fuel pump and if it is clogged or torn it will lead to premature failure so changing this unit is a must.7. The Fuel Pump itself.8. Fuel filter always needs to be changed at servicing since it captures debris and protects the pump.9. Last but not least the injectors should be checked as well. source: http://www.buyautoparts.com/howto/repair-fuel-pump.htm
  • 19. How To Fix a Fuel Pump? The EndFor more Auto How To Tips visit, http://www.buyautoparts.com/howto/If you need to purchase an auto part- Visit www.buyautoparts.com- Call 1-888-907-7225- Or send an email to sales@buyautoparts.com THANKS source: http://www.buyautoparts.com/howto/repair-fuel-pump-parts.htm