Inspecting Fuel Tanks For Filter Clogs

Inspecting Fuel Tanks For Filter Clogs

Any number of things may cause a fuel filter to plug up. One is a rusty fuel tank. Steel fuel tanks are coated inside with a special "tern" plating to resist corrosion. Over time, the protective plating can wear away and expose the steel, making it vulnerable to corrosion. Water in the fuel accelerates the process.

fuel pump assembly

Any number of things may cause a fuel filter to plug up. One is a rusty fuel tank. Steel fuel tanks are coated inside with a special “tern” plating to resist corrosion. Over time, the protective plating can wear away and expose the steel, making it vulnerable to corrosion. Water in the fuel accelerates the process. As the steel rusts, the rust flakes loose, settles to the bottom of the tank and may be drawn into the fuel pump. The fuel pump pickup tube has a mesh filter sock on the end to prevent large particles from being sucked into the pump. This protects the pump, but particles that are smaller than the mesh screen will still pass right through. When they reach the fuel filter, the much finer filter media traps contaminants as small as 5 to 25 microns in size. This prevents the particles from reaching the fuel injectors (which have extremely close tolerances). This gunk builds up and eventually plugs the filter.

The fix is to drop the fuel tank, remove the fuel pump and inspect the inside of the tank. If it is full of rust, cleaning it is a waste of time. The fuel tank needs to be replaced.

fuel pump inspection

Fuel filters can also become clogged with fuel varnish deposits, dirt and plastic residue. If a fuel tank that has never been filled with gasoline that contains alcohol is filled with such fuel, the alcohol will act like a solvent and loosen all the accumulated fuel varnish, dirt and other gunk inside the tank. Alcohol is a great fuel system cleaner, but that first dose may loosen so much gunk that it may plug up the filter. Most late-model vehicles are designed to safely run on gasoline blends containing up to 10 percent ethanol, and flex-fuel vehicles can handle blends of up to 85 percent ethanol (E85). Gasoline/alcohol blends are common in the Midwest, but are not used as much in many other areas of the U.S. Consequently, if the fuel system has never seen alcohol, that first dose might cause a problem.

If a fuel tank contains dirt, it will eventually wind up in the filter. As with a rusty tank, the tank needs to be removed from the vehicle, opened up and inspected. If dirty, it can be steam-cleaned, air-dried and returned to service.

On vehicles that have plastic fuel tanks, it’s not unusual for the plastic to start to deteriorate after 10 to 12 years of service. The gunk that flakes off the inside of the tank can also plug the filter. The fix is to replace the fuel filter and the fuel tank.

You May Also Like

Simple Engine Fasteners Actually Complex Engineering Systems

Fasteners act much the same as a spring due to the physics of stretch and rebound.

While the design and use of automotive fasteners may seem simple, proper installation actually involves many different factors. There are many nuances in the selection and application of fasteners that can make the difference between a well-built engine and a candidate for self-destruction.

The first thing to understand is that fasteners act much the same as a spring due to the physics of stretch and rebound. A stud or bolt must be stretched to produce clamping force. For example, a typical 3/8˝ connecting rod bolt will need to be stretched some .006˝ to provide 10,000 lbs. of force.

Superchargers: Pros And Cons

Customers generally look to superchargers for the instant throttle response, not fuel economy.

Runners And Ports: How Modern Engines Manage Air

Variable-length intake runners change the length of the intake passages depending on engine speed and load.

Driveshaft Universal Joint Tips And Techniques

Before removing the driveshaft, check for play in the yoke and slip joint. If the u-joints are failing, you should be able to see movement in the shaft as you apply leverage.

VIDEO: Best Practices For Turbocharger Life

Doug Kaufman discusses some simple things your customers can do to ensure the longest life of their turbochargers. Sponsored by MAHLE.

Other Posts

Voltage Drop Testing

The measurement of voltage is like the speed of the traffic.

Fuel Pumps and Cranking

Diagnosing the problem comes down to understanding what causes a loss of fuel pressure.

Acura High-Pressure Fuel Pump 

Follow the correct repair procedures for a high-pressure fuel pump that is making a chirp.

GDI Fuel Pump Pressure Control (VIDEO)

A high-pressure direct injection fuel pump can vary the pressure to the injectors. Sponsored by Carter Fuel Systems.