Volkswagen Golf/Jetta/Cabriole 1990-1999

Fuel Filter

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Relieving Fuel System Pressure





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Fig. Fuel filter location-1994 Jetta

All gasoline engines equipped with electric fuel pumps maintain fuel pressure even when the engine is not operating. Because of this, residual pressure may remain in the fuel system for several hours after the engine is shut down.

To relieve the fuel system pressure on vehicles equipped with gasoline engines, perform the following:

  1. Locate the fuel pump fuse, and remove it from the fuse panel.
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  3. Operate the engine until it runs out of fuel and stops.
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  5. Remove the fuel filler cap.
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  7. For safety purposes, disconnect the negative battery cable.
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NOTE
When the battery is disconnected, the radio security code will need to be reset. Be sure you obtain the security code (if the radio is equipped with a security system) before performing this procedure. Also, the engine management system's adaptive memory parameters may be lost; as a result, the vehicle may operate erratically for the first few miles after the battery is disconnected.

  1. Proceed with the necessary fuel system component repairs. When finished, install the fuel pump fuse and connect the negative battery cable. Don't forget to install the fuel filler cap.
  2.  

REMOVAL & INSTALLATION



Gasoline Engines


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Fig. Always use a back-up wrench to hold the fuel filter when loosening or tightening the fittings

The fuel filter removes particulate matter from the fuel system which might clog the fuel distributor block or fuel injectors. All gasoline vehicles covered by this guide are equipped with "lifetime" fuel filters. According to the manufacturer, unless the fuel system is damaged or contaminated, the filter is large enough to handle all normal fuel filtering requirements for the life of the engine. However, changing this filter more often than recommended can ease the load on the fuel pump, especially on higher mileage vehicles.

On gasoline engine-equipped vehicles, the fuel filter is under the car next to the fuel pump reservoir and looks like a large, metal container. Arrows point the direction of fuel flow through the filter. Banjo type fittings with copper gaskets connect the fuel lines to the filter. Always replace these gaskets any time the fittings are loosened.


CAUTION
Never smoke when working around gasoline! Avoid all sources of sparks or ignition. Gasoline vapors are EXTREMELY volatile! This procedure will cause a small fuel spill. Make sure the work area is well ventilated, and observe appropriate fire safety precautions.

  1. Relieve the fuel system pressure.
  2.  
  3. Raise and safely support the rear of the vehicle. Have a pan ready to catch the fuel that will run out of the reservoir.
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  5. Have a rag handy and wear safety glasses when loosening the fittings. The system will be under pressure and fuel will be sprayed.
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  7. Hold the filter with a 19mm or 22mm wrench and loosen the fittings with a 17mm wrench. Wrap the filter and wrenches with a rag to contain any pressurized fuel. Have the catch pan ready.
  8.  


NOTE
Always use a back-up wrench to hold the filter, or the fuel lines may be damaged.

  1. Disconnect the fuel lines, loosen the mounting bracket and remove the filter.
  2.  
  3. Install the new filter but do not tighten the mounting bracket yet.
  4.  
  5. Make sure all fittings and sealing surfaces are clean. Install the banjo bolts with new copper gaskets and torque to 14 ft. lbs. (20 Nm).
  6.  


NOTE
After replacing the fuel filter, it may take several attempts to start the engine. This is because the fuel pump needs to operate (while the engine is cranking) to pressurize the fuel system.

Diesel Engines


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Fig. Diesel fuel filter detail

With diesel engines, absolute cleanliness is essential for the fuel system components. The injection pump of a diesel engine has extremely close tolerances; even small particles of dirt can seriously affect performance.

Changing the fuel filter on vehicles equipped with diesel engines is one of the most basic, yet critical forms of preventative maintenance. Replacement of the filter every 30,000 miles is recommended.

  1. Open the fuel filler cap to relieve any pressure that may be in the tank.
  2.  
  3. Disconnect and plug the supply line and injection pump fuel lines from the filter.
  4.  
  5. Remove the clip from the control valve (located on top of the filter), then remove the valve, leaving the two lines connected. Position the valve and the lines off to the side.
  6.  


NOTE
The control valve is delicate, so be careful during removal and installation.

  1. Loosen the mounting clamp nut/screw, then lift the filter assembly straight up. Discard the old filter.
  2.  

To install:

  1. Install the new filter onto the mounting clamp. If there are arrows indicating fuel flow direction, they point towards the front of the vehicle. Tighten the mounting nut/screw until the filter is secure.
  2.  
  3. Install new control valve O-ring seals (using fresh diesel fuel for lubrication) and install the control valve into the flange on the top of the filter. Secure the retaining clip.
  4.  
  5. Connect the fuel lines to the filter. Use new clamps if they are damaged.
  6.  
  7. Connect the negative battery cable, then start the engine. Accelerate the engine a few times (this will clear the air bubbles in the fuel system) and check for fuel leaks.
  8.  
  9. Don't forget to tighten the fuel filler cap.
  10.  

 
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