If an electric fuel pump is not working, is not delivering enough fuel pressure to meet specifications, or is not pumping enough fuel volume to keep up with the engine's needs, the pump may need to be replaced. But before that happens, you should rule out all the other possibilities such as a plugged fuel filter, restricted fuel line, bad fuel pressure regulator, bad fuel pump relay, or fuel pump wiring problem. If all of these have been checked and eliminated, you can go ahead and replace the pump.
NOTE: The Fuel Pump Manufacturers Council says many fuel pumps are replaced unnecessarily or are returned under warranty because the fuel pump was not correctly diagnosed. So save yourself the time and trouble and make sure the pump is really bad before you buy a replacement pump.
In-Tank Electric Fuel Pump Replacement
The electric fuel tank on most vehicles with electronic fuel injection is located inside the fuel tank. If there is no access panel under the back seat or in the trunk of the vehicle, it means you will have to lower the fuel tank from the vehicle to replace the pump. This can be a difficult job, so you may want to take your vehicle to a service facility for repairs rather than trying to do it yourself.
WARNING: Gasoline is extremely flammable. Do not smoke when working on the fuel system, and keep any sparks or other sources of ignition away from the vehicle and fuel tank. Do NOT use an incandescent trouble light near the fuel tank as the hot surface of the light bulb can ignite any fuel that might spill or splash on it. Fuel vapors are heavier than air and can also travel a long distance along a garage floor. The fumes can be ignited by a heater, pilot light, electric motor or other source of ignition some distance away. Also be aware of the fact that static discharges can also ignite fuel. Proceed with caution.
Before you go to all the work of removing the fuel tank, double-check under the back seat and in the floor of the trunk for an access panel to the fuel tank. If the vehicle has one, you can change the pump without dropping the tank. Just skip the next couple of steps and undo the plate the holds the pump in the tank.
Before unbolting the straps that secure the fuel tank in place, remove as much fuel as possible from the tank. This will lighten the tank considerably and make it much easier to handle, lower and lift back into place. Some gas tanks have a drain plug in the bottom, but most do not so you will have to use a hand siphon pump to drain the tank (do NOT use an electric drill powered pump as the sparks may ignite the fuel!). Insert the hose down the filler neck and use the hand pump to start the siphon action. Do NOT suck on the hose to start a siphon because gasoline is poisonous and the fumes can harm your lungs. Drain the fuel into an approved container (a metal or plastic gas can, NEVER an open bucket), and seal the container once all the fuel has been drained from the tank. Do NOT leave open containers of gasoline sitting around.
How to Replace an In-Tank Electric Fuel Pump
Set the parking brake and place the transmission or transaxle in park (in gear if it is a manual transmission). Also, block the front wheels so the vehicle can't roll when you raise the rear wheels off the ground. The vehicle should also be parked on a level surface.
Raise the rear of the vehicle as needed with a jack, and support the vehicle with a minimum of TWO jack stands (make sure the stands have the proper weight rating to handle the weight of the vehicle). NEVER crawl under a vehicle that is only supported by a jack.
Disconnect the filler neck from the fuel tank by loosening or removing the clamp that holds the hose on the tank.
Remove either the front two bolts or the rear two bolts that secure the fuel tank straps to the vehicle. Then gently lower one end of the tank. This will allow you to reach the wiring connections, fuel line and vent hoses on top of the tank. Disconnect the wires and hoses before removing the two remaining bolts that hold the other end of the straps. The tank can now be lowered from the vehicle.
Once the tank is sitting on the ground, you can undo the plate on the top of the tank the holds the fuel pump in place. The plate may have a metal ring that has to be rotated counterclockwise to remove the ring. Or, the plate may be held in place with screws or bolts. Once this plate has been loosened, the plate, fuel pump and sending unit can be carefully pulled out of the tank.
Get the Correct Replacement Pump
Once you have removed the old ful pump from the tank, you can buy a replacement pump online or from your local auto parts store. Make sure you get the correct replacement fuel pump for your vehicle. Many pumps appear similar on the outside but may have different flow rates and pressure ratings.
On some applications such as GM Flex Fuel vehicles and others, the engine VIN code may be necessary in addition to the year, make and model to look up the correct replacement pump.
Some replacement pumps may not look exactly the same as the original. That's because some older vane and georotor style fuel pumps have been discontinued and replaced with newer, more efficient turbine style fuel pumps. Turbine pumps are better because they use less amperage, spin faster and provide longer life and quieter operation.
We would also recommend buying a name brand electric fuel pump rather than Made-in-China pump. The cheap Chinese pumps have a poor reputation for quality and durability, and may fail at low mileage.
Another piece of advice is to replace the whole fuel pump module assembly rather than just the pump itself. Yes, it costs more to buy a module than a bare pump, but the module makes installation a LOT easier and it reduces the potential for additional trouble later. On older high mileage vehicles, the plated metal electrical contacts on the fuel sender unit lever arm are often worn or corroded, affecting the units ability to send an accurate fuel level signal. Also, on newer vehicles with returnless EFI systems, the module also has the fuel filter built into it (which may or may not be available separately). A new sending unit and filter come preinstalled with a new fuel pump module assembly, along with new wiring.
On some newer vehicles with returnless EFI systems, you can't even buy the fuel pump separately. You have to replace the entire fuel pump module.
Pump and Tank Inspection
Clues as to why the pump failed may be found by examining the filter screen on the pump inlet, and peering into the tank itself. If the filter screen is clogged with dirt or rust, the fuel tank will probably need to be cleaned or replaced. Dirt can be removed by steam cleaning or pressure cleaning the inside of the tank and allowing it to dry. If the fuel that was drained from the tank is dirty, it should be disposed of or run through a coffee filter before it is reused. If the tank is steel and it is rusty inside, you should replace it with a new one. Nothing will kill a new fuel pump faster than installing it inside a dirty tank. The gas tank should be replaced if it is leaking.
Inspect the wiring harness that connects to the old fuel pump. Loose, corroded or damaged connectors or wires can create excessive resistance that will reduce current to the pump and cause it to run slowly or not at all. Fix any wiring faults that need repair BEFORE you install the new pump.
When you install the pump in the tank, put a new filter screen on the pump (a new screen usually comes with the pump). If you are replacing the entire fuel pump module assembly, it will come complete with a new inlet filter screen and fuel level sending unit.
A new gasket or seal should also be installed on the top plate to prevent leaks.
Inspect the fuel and vent hoses. If any of the hoses are cracked, leaking or damaged, replace them with new hoses. For fuel hoses, be sure to use high pressure hose that approved for EFI use (not carburetor or vapor hose which lacks an adequate pressure rating). New hose clamps are also recommended.
Once the pump has been installed in the tank, reinstall the fasteners or locking ring that holds the pump cover to the fuel tank. Reconnect the wiring harness to the pump, making sure all the connectors are clean and tight. You can use dielectric grease on the connectors to keep out moisture that could cause corrosion later on.
Reconnect the EVAP system vapor hoses to the fuel tank, and the fuel line to the fuel pump outlet. Make sure all hoses are correctly routed.
Raise the fuel tank back into place and reinstall the support straps that hold it in place.
Reconnect the fuel filler hose to the fuel tank inlet. Make sure all clamps are tight.
Add several gallons of fuel to the tank and check for leaks. The tank should be at least 1/4 full to provide enough fuel for proper fuel pump lubrication and cooling before starting the vehicle.
Install a new fuel filter in the fuel supply line. Do not reuse the old in-line fuel filter as it may be dirty and restrict fuel flow to the engine.
Start the engine and check all fuel line connections for leaks. No leaks? Great, you're done.
Aucun commentaire:
Enregistrer un commentaire