Filters For Your Fuel System

Any filter (with the exception of a small plastic one) should be rigidly clamped to a chassis member. If a filter is loose enough to bounce around, then it could loosen its connections and cause an air leak. Air leaks in the suction-side line going to the pump are a major cause of fuel supply problems.

While on the subject of fuel lines, there are some do's and don'ts. The fuel line that runs from the fuel cell to the pump should be either the steel braid type or a steel line similar to OE. You should not use aluminum or copper lines. Both of these materials will fatigue, harden, and crack due to vibration. If a crack forms, it will be at a fitting where the mounting is rigid but the line can flex.

Rubber fuel lines are often used in Street Stocks and similar cars. Although designed for use as a fuel line, it is not recommended for the entire fuel system. If used for the length of the system, this line should be routed in a protected area of the car. Often, rules allow the fuel line to be run through the driver's compartment in a tube or pipe, but it is far better to route the line under the floor and inside a framerail. It should be tied down so that a rough track won't sling it out. The rubber line has one other undesirable characteristic. When used between the fuel pump and the carburetor, the black rubber sometimes absorbs enough heat to cause a vapor lock. This can make it difficult to restart when it's been a while since you've finished your heat race and it's time for the feature to begin.

Be aware of the following things when using steel tubing for the fuel line. When attaching the steel line to the fuel cell, an AN fitting will usually be needed to adapt the line to the fuel cell. It is common to use a short piece of rubber fuel line to join the two. This is acceptable if the proper fitting cannot be found. The steel line should have a flare fitting of the proper size to mate with the AN fitting. This line can usually be purchased in auto parts stores in lengths from 1 foot to 5 feet. A line can be easily fabricated using these sections. A short piece of rubber fuel line (8 inches is plenty) should be used at the pump end of the steel line. This would be true even with solid motor mounts. There needs to be a flexible link at the pump. Do whatever is necessary to keep the line away from exhaust and engine heat, even if it means stringing the steel line inside the framerail, going past the pump, and then doubling back.

If it is necessary to flare the steel tubing, you must use a double-flare tool. With the common single-flare tool, the steel will often crack at the outer edge of the flare, which will eventually cause a leak.

Steel braid AN hoses are best for running fuel lines. They have the flexibility to be removed, cleaned, repaired, and reinstalled. Fittings are available for nearly every application, thus making this type of hose ideal for tight spaces.

There are two more filters needed in your system. The first filter is on the fuel cell vent. As fuel goes out, air comes in, along with dust and humidity. A vent filter will keep your fuel drier and cleaner. The second and last filter needed is in your funnel. Any filter here would be better than none.

Whatever means you choose to plumb your fuel system, do so with safety in mind. Use the best materials you can afford and use the correct type of filter. Protect all fuel lines from the hazards of the racetrack.