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Frame Off Restoration - Step 4 - Restoring the Fuel System


Every car has some form of fuel system. Depending on the age of the vehicle the primary differences you will see relate to newer cars, especially from the seventies onwards. This is due to governmental regulations about emissions of vehicles as well as engineering imrovements. So, while your fifties car may have simply have a fuel tank, sender and mechanical fuel pump, a newer car could have evaporative controls, charcoal cannisters, return fuel lines, fuel filters and be pressurized for fuel injection. For the scope of this article the fuel system is defined as everything between the fuel delivery (carburetor or fuel injection) and the fuel fill tube.

Note: We are working with the fuel system and this means gasoline. It will be present in the bits you're working on. So, no open flames, sparks, etc. You blow up, it's your own fault.

Disassembly and Restoration

Gas Tank

The first step is to drop the tank. Gas tanks are generally held in place by three or four bolts. I like to put my floor jack underneath the tank (if it's underneath the vehicle) to support it as I'm removing the bolts. In many cases you don't know how much gasoline is in the tank. This helps you keep from accidentally dumping the contents in your garage. You also need to disconnect the fuel sender wiring. Most fuel fill tubes are connected to the gas tank with a rubber tube connector. Unhook the rubber connector at the fuel fill tube (not the gas tank!). The last connections will be the main fuel line and any return lines. If the car has return lines, disconnect those first. The very last item to disconnect is the fuel line. Because it sits so low on the gas tank it helps if you can tip or pitch the tank away from this connection to avoid spilling gasoline. Put a coffee can under the connection to catch any gasoline spills. Have a baggie and tape ready, then remove the connection. Put the baggie over the fuel line and tape it shut to avoid spills.

Now, I really recommend the Fuel Tank Repair Kit from the folks at POR-15. But, I also add some steps to the process. On old tanks, you can build up a lot of rust scale and dirt in the bottom of the tank. Rinse it out with the garden hose on full bore, then add a littledish soap and repeat. What you're doing it minimizing the flammability of the interior of the tank. Next, take a length of chain or a few handfuls of rough edged gravel (whatever's handy) and put it in the tank. Add a little water in there as well. Now, shake the tank back and forth a bit. The movement of the chain or gravel will help to knock loose anything else that's in there. Depending on the condition of the tank, rinse lather and repeat. If you are using the POR-15 kit, it comes with a product called Marine Clean. Use this as the last cleaning step on the interior. It'll remove the last of the gack out of the tank. Additionally, it will help to neutralize the gasoline.

Now, the gas tank repair kits are geared towards dealing with the interior of the tank, not the exterior. Set the tank aside for a bit to dry. While it's drying go ahead and purge the rest of the fuel from the system. Put your coffee can under the fuel line you disconnected. Remove the bag you previously put over it. The fuel should then drain out into the can. If there's enough vaccum in the line to keep the fuel from pouring our go ahead and loosen the line up where it connects to the carburetors. Now, some fuel pumps have backflow valves to prevent fuel from flowing backwards through the line. You may need to additionally disconnect the line on the front side of the fuel pump. Pour off the gasoline into the cheesecloth with the fuel from the tank.

Now that the tank is dry it's time to account for the exterior of the tank. From my experience the bottom of the fuel tank generally will have a "road coating" on it. You know; grease, oil, tar, dirt, etc, that has been picked up over the years. The top of the tank should be relatively clean. First, make sure that the tank doesn't overly smell of gasoline. Then plug the holes going into the tank with shop towels. First go over it with a wire brush, and then sand paper to prep the surface for paint.

This is again where I really like the POR-15 products. Use the Metal Ready product to prepare the surface. Follow it up with a coat of their POR-15. Once that's dry add a final coat of Chassis Coat. The combination of POR-15 as a rust preventative and Chassis Coat as a UV protectant make for a bulletproof combination. Once the Chassis Coat is dry, follow the rest of the instructions for the tank sealer kit. It's very similar to the process we just followed. Prep with Metal Ready and then slosh around the tank sealer. The instructions that come with the kit are really good, so I won't reproduce them in detail here.

Fuel Lines

In between drying phases on the gas tank it's time to remove the old fuel lines. You have a decision to make here. You can either try to restore the existing fuel lines, or go ahead and replace them. Here's an area where I recommend replacing the part rather than restoring it. This being said, it's entirely up to you.

If you choose to restore the fuel line the first step is to clean the exterior of the line. I generally start with a coarse grit (60) to do the rough cleaning and progressively work towards a 150 or 220 grit paper. If the line has fittings on the ends I use my dremel with a wire wheel to clean the threads. To clean out the interior of the line use an air gun on your air compressor to blow out the line. To add more cleaning power, tip some sand into the end of the pipe and blow it through with the air gun. You'll want to ensure that the overall thickness of the pipe is sound, otherwise you'll have to replace it. To maintain an original appearance on the line, but ensure it's protected you can sray the exterior of the fuel lines with a clear coat paint. This will keep the fuel line from rusting in the future.

Additionally, there are frequently some form of clamp that holds the line to the car. Remember, this is a restoration. Use a Dremel tool, wire wheel, wire brush or similar tool to clean the bolts and nuts (if so equipped). Additionally, you'll have clamps that hold the line in place. Throw them in the sandblaster and clean them up. If you don't have a sandblaster, a wire wheel on a drill, sandpaper, or similar tool will enable you to clean them up. Once cleaned up you can then paint them with POR-15 and Chassis Coat.

If there is any rubber fuel lines on the car go ahead and measure them for length and determine the fuel line type. Rubber fuel lines are pressure rated, so if you're dealing with a fuel injected car you'll need to ensure that you replace it with the correct pressure rated line. Old rubber isn't worth saving. So add the line to your parts list. This you'll be able to pick up at your local autozone type store.

Fuel Sender

Fuel senders work by having a float arm that rises and falls with the level of gasoline in the tank. As that arm rises and falls it varies the resistance by moving across a variable resistor. That resistance information is passwed across the wiring to the fuel gauge. Some sending units are rebuildable (new float and or variable resistor) others must be replaced. You'll need to get the resistance specifications for the sender unit and test it with a multitester to ensure it works correctly. While you're at it, you can clean the terminals on the sender unit and the connectors on the wires that connect.

Fuel Pump

To test your electric fuel pump get out your gas can (I'm assuming you have a gas can for filling the lawnmower or similar tools). Connect some rubber fuel line to each side of the fuel pump. Insert the supply line into the gas can. Put the return line there as well, but above the level of the supply. Then connect the fuel pump to an approriate voltage source. If the fuel pump works correctly you'll see it draw in and pump out fuel. Now, even if the fuel pump works I recommend putting one on your parts list. On many cars (especially British ones) these have the tendency to fail at inappropriate times. In fact, some folks install a failover fuel pump in their restoration for worst case scenario situations.

To test your mechanical fuel pump you'll want to investigate the movement of the mechanical assembly and the diaphram that creates the suction based on the mechanical movement. These diaphrams are generally made from rubber and deteriorate with time. You'll want to add a fuel pump rebuild kit to your parts list. Once you obtain the rebuild kit you need to disassemble the unit, remove all the replaceable parts and clean up the assembly. If it's a painted unit, repaint it correctly. If not, consider a clear coat paint to rotect the unit. With the parts cleaned up reassemble the unit.


With the various parts restored or replaced, go ahead and store them away. Obviously fuel lines will probably not fit within your 12 gallon container boxes. I like to use a piece of form tubing (that you make concrete forms with) as a means of storing long parts such as this. Now your fuel system will be ready for a rapid reassembly.

On to Step 5: Interior Soft

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Contents copyright 2008, 2009 - Jody F. Kerr

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