Replacing Fuel Tank Switch In Classic Ford Trucks

If you're having trouble with the fuel tank switch on your 1973-1979 Ford Truck, you're not alone. Many owners of these classic trucks have experienced issues with the switch that controls the selection of the front and rear fuel tanks. In this guide, we'll cover some common problems and provide step-by-step instructions on how to change the fuel tank switch, so you can get back on the road with confidence.

Troubleshooting a faulty switch

First, it's important to understand the symptoms and the specific behaviour of the switch. Is it failing to switch between the front and rear fuel tanks? Is the fuel gauge behaving erratically or indicating the wrong tank levels?

If the switch is acting up, the root cause could be a faulty connection or a failing component. Try cleaning the connections and performing some multimeter work to narrow down the possibilities.

If the switch is not switching between tanks, the issue could be with the switch itself, the valve, or the solenoid. To troubleshoot, turn the key to the "Run" position without starting the engine. Then, switch the lever between the two tanks, waiting about 15 seconds between each action. Get on your hands and knees and feel under the cab floor to see if you can hear or feel the solenoid moving back and forth. If the solenoid is not moving, it may need to be replaced.

If the fuel gauge is not reading correctly, the issue could be with the switch, the valve, or the fuel level sensor. Try wiggling the switch lever or moving it up and down to see if the gauge responds. If the gauge still doesn't read correctly, the fuel level sensor may need to be checked or replaced.

If the switch has completely failed, the fuel solenoid should default to one of the two tanks, but it's not clear which one. The truck should continue to run as long as one of the tanks has sufficient fuel, but the fuel gauge may not accurately reflect the correct tank.

In the short term, you can rig up a toggle switch or jump the switch to tie it permanently to one tank until you can find a replacement.

For further troubleshooting, it's recommended to consult a Ford specialist or a trusted mechanic who can provide more specific advice based on their expertise and experience.

Finding replacement parts

If you are looking to replace the fuel tank switch on your 1973-1979 Ford Truck, there are a few options available to you.

Firstly, it is important to correctly identify the part you need to replace. The fuel tank switch is typically located on the dashboard or in the heater control panel. However, some models may have a valve handle sticking up through the floor or a switch on the tank itself. Once you have located the switch, you can then begin to look for replacement parts.

One option is to search for used or second-hand switches. Forums and online marketplaces, such as eBay, can be a good source for these parts. It is worth noting that while used parts may be cheaper, they may not be as reliable as new parts and could potentially fail sooner.

Another option is to purchase a new, aftermarket switch. There are several online retailers that specialise in Ford Truck parts, such as LMC Truck and Broncograveyard.com. These websites offer a range of new parts, including fuel tank switches specifically for the 1973-1979 Ford Truck models. When purchasing new parts, ensure that you have the correct model number for your truck, as some parts may only be compatible with certain models or years.

Additionally, you can try contacting your local Ford dealership or a Ford specialist mechanic. They may have the replacement part you need in stock or be able to order it for you.

Finally, if you are unable to find the exact replacement part, it may be possible to rig up a temporary solution. As suggested in the forum post, you could use a simple toggle switch as a temporary workaround until you can find the correct factory-style switch.

Installing a new switch

First, locate the fuel tank selector switch. For the 1973-1979 Ford F-Series trucks, the dash-mounted switch is typically located on the heater control panel. The switch allows you to select between the front and rear fuel tanks.

Next, gather the necessary tools and materials. You will need a new fuel tank selector switch, which you can purchase from automotive part stores or online. Make sure to get the correct part number for your specific Ford model. You will also need basic hand tools like screwdrivers and wrenches for the installation.

Before removing the old switch, take note of the wiring diagram and how the wires are connected to the switch. You may want to take pictures or make notes for reference during the installation of the new switch. Carefully disconnect the wires from the old switch and remove it from the heater control panel.

Now, you can install the new switch. Fit the new switch into the heater control panel and secure it in place. Reconnect the wires according to the wiring diagram, making sure they are securely attached to the correct terminals.

Once the new switch is installed, test it to ensure it is working properly. Turn on the ignition and try switching between the front and rear fuel tanks. Check that the fuel gauge accurately reflects the tank selection. If the switch is working correctly, you have successfully installed it.

Finally, ensure that you securely fasten the new switch and that all wires are tucked away safely. This will help prevent any accidental damage or disconnection. Test your Ford Truck on a road trip to ensure that the fuel tank switch is working as expected.

Wiring diagrams and requirements

The wiring diagrams for the 1973-1979 Ford F-series trucks are available online and should be consulted for detailed information. These diagrams are model-specific, with separate diagrams for the F100/F350 models.

The wiring diagrams cover the following components:

• Fuel tank selector switch (dash)
• Fuel gauge
• Fuel tank selector valve and solenoid assembly
• Selector switch
• Electronic integrated switching
• Auxiliary fuel tank switch

The wiring diagrams will show the specific wiring connections and configurations for each of these components, ensuring proper installation and function.

It is important to note that there were different fuel tank systems used in the 1973-1979 Ford trucks. From 1973 to 1974, a manual control selector valve was used, and the switch only controlled the fuel gauge, switching it from one tank to the other. From 1975 to 1979, an electronic control selector valve was utilised, and the switch controlled both the tanks and the fuel gauge.

The wiring requirements for the fuel tank switch involve ensuring that the correct number of wires is connected to the switch. For the 1975/76-1980 Solenoid system, four wires run through the firewall: two tank sender wires, one dash gauge feeder wire, and one solenoid valve power wire. The dash switch is a five-terminal DPDT (Double Pole Double Throw) ON-ON rocker switch.

Additionally, it is worth noting that the wiring colours may vary by year and can be found in the wiring diagrams specific to your truck's year of manufacture.

When working on the fuel tank switch, it is important to consult the appropriate wiring diagrams and follow the specified wiring requirements to ensure proper functionality and safety.

Differences between model years

The sixth generation of the Ford F-Series, also known as the "dentside Ford", includes pickup trucks and medium-duty commercial trucks produced from the 1973 to 1979 model years.

1973 Model Year

The 1973 model year was launched in December 1972. The fuel tank was moved out of the cab to below the pickup bed, creating a storage area behind the bench seat. The F-350 V8 was introduced, designed with contractors and camping enthusiasts in mind. The F-350 had a longer wheelbase than the F-100 or F-250 but the same overall length. The Camper Special package for the F-350 SRW was designed for heavier slide-in campers. The F-250 4x4 was offered with three engines: the 240 inline-6, the 300 inline-6, and the 360 V8.

1974 Model Year

The F-Series became available in an extended cab for the first time. Dubbed the "SuperCab", it offered six-passenger seating in a shorter length. The F-100, F-250, and F-350 were offered with the Explorer package, consisting of colour-keyed exterior and interior trim, badging, and wheel covers. The F-350 SRW with the Camper Special package was renamed the "Super Camper Special".

1975 Model Year

The F-150 was introduced, designed with a higher GVWR and maximum payload. The F-Series received a slight facelift, with black accents around the headlights and a refined overall appearance. The F-250 4x4's 360 V8 engine was replaced by the 351M and 400 V8s.

1976 Model Year

A Bicentennial Option Group was offered on Custom styleside pickups, with a golden eagle stripe on the side and red, white, and blue cloth inserts on the seats.

1977 Model Year

The exterior trim was redesigned, with the cowl insignias made smaller and moved near the windshield. The bed received a rectangular fuel door to conceal the gas cap. The fuel tank located behind the seat was discontinued due to safety concerns. The medium-duty F-500 series was discontinued. The "Super" was dropped from the "Super Camper Special" name, with F-350 models with camper packages now called "Camper Special". The F-250 4x4 began to be offered with a "married" transfer case, attached to the transmission.

1978 Model Year

The split grille gave way to a larger single-piece grille which no longer incorporated the headlamps, turn signals, or Ford logo. The headlamps were located in housings outboard of the grille, with the turn signal lamps below them. A chrome-plated Ford logo was placed on the hood above the grille. Round headlamps were used on the Custom trim level, while the Ranger, Ranger XLT, and Ranger Lariat trim levels had new rectangular headlamps with optional chrome bezels and a chrome grille insert. Dual fuel tanks in the bed became standard. Part- or full-time four-wheel-drive was offered on SuperCab models. The F-100 4x4 was introduced in Australia, fitted with the 302 Cleveland V8 engine.

1979 Model Year

All models used rectangular headlamps, with bezels available in either black or chrome to match the aluminium grille frame.

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