Fuel Tank

Complete removal and replacement of the fuel tank on a 1966 Chevrolet Corvette, including draining fuel, disconnecting lines and filler, and dropping the tank from the vehicle.

Warnings

Tools required

Parts

• Fuel tank (if replacing) × 1 — Use OEM specification or equivalent 20-gallon tank for 1966 Corvette
• Fuel tank straps × 2 — GM part number 3850517 or equivalent
• Fuel tank sending unit gasket × 1 — Use OEM specification
• Fuel tank filler neck hose and clamps × 1 — Use OEM specification
• Fuel line hose sections (if deteriorated) × 1 — 5/16" fuel-rated hose
• Hose clamps (assorted) × 6 — Worm-drive clamps, sizes 12-16

Preparation

1. Park vehicle on level, paved surface outdoors or in a well-ventilated garage with no ignition sources within 50 feet
2. Ensure fuel tank is no more than 1/4 full; if fuller, drain or drive vehicle to reduce fuel level before beginning work
3. Place Class B fire extinguisher within immediate reach of work area
4. Disconnect negative battery cable to eliminate electrical ignition sources
5. Allow engine and exhaust system to cool completely (minimum 2 hours after last operation)
6. Raise rear of vehicle using floor jack and support securely on jack stands under the frame rails behind the rear wheels, ensuring vehicle is stable and level
7. Chock front wheels to prevent vehicle movement

Procedure

1. 1

   Drain fuel from tank
   Using a siphon pump or fuel transfer pump, remove as much fuel as possible from the tank through the filler neck. Transfer fuel to approved, sealed fuel containers. Leave containers outdoors and away from the work area. Even after draining, expect 1-2 gallons of residual fuel to remain in the tank. Position a large fuel-safe drain pan under the tank to catch remaining fuel during removal.
2. 2

   Remove filler neck connection
   Locate the fuel filler neck where it connects to the tank on the driver's side. The filler neck is secured with a rubber hose and typically two hose clamps. Use a flat blade screwdriver to loosen the hose clamps, then carefully twist and pull the filler neck hose off the tank inlet pipe. Fuel will drain from this connection; be prepared with rags and drain pan.
3. 3

   Disconnect vent line
   Locate the fuel tank vent line, a small diameter hose running from the top of the tank toward the filler area. This line prevents vapor lock and tank pressurization. Loosen the hose clamp and disconnect the vent line from the tank fitting. Cap or plug the line to prevent debris entry.
4. 4

   Disconnect fuel outlet line
   Locate the main fuel outlet line at the front of the tank. This is typically a 5/16" steel line with either a threaded fitting or hose connection. If threaded, use a line wrench to prevent rounding the fitting while loosening. If hose-connected, loosen the clamp and slide the hose off. Be prepared for residual fuel spillage. Cap or plug the line to prevent contamination.
5. 5

   Disconnect fuel return line (if equipped)
   Most 1966 Corvettes do not have a fuel return line. If your vehicle is equipped with one, disconnect this line using the same method as the outlet line. If your vehicle does not have a return line, skip this step.
6. 6

   Disconnect fuel sender electrical connection
   Locate the fuel sending unit on top of the tank, accessed from underneath. Disconnect the electrical wire connector from the sending unit terminal. This is typically a single-wire push-on connector. Note the orientation for reinstallation.
7. 7

   Position support for fuel tank
   Position a transmission jack or wide-padded floor jack under the center of the fuel tank. Raise the jack until it just contacts the tank bottom, providing support but not lifting. The tank should rest firmly on the jack pad. Ensure the jack is stable and centered to prevent the tank from tipping during removal.
8. 8

   Remove tank strap fasteners
   The fuel tank is secured by two metal straps that loop under the tank and bolt to the frame on each side. Locate the 4 strap mounting bolts (2 per strap, one at each end). Verify the exact strap bolt size against factory documentation before purchasing tools; common sizes are 1/2" or 9/16" hex head, but confirm for your vehicle. Apply penetrating oil and allow to soak for 10-15 minutes if bolts show corrosion. Using a socket and ratchet, remove all 4 bolts. Support the straps as you remove the final bolt on each side to prevent them from falling.
9. 9

   Lower and remove fuel tank
   With the straps removed, slowly lower the transmission jack while guiding the tank down. Watch carefully for any remaining connections, wires, or hoses that may still be attached. The tank should lower freely once all connections are removed. As the tank lowers, residual fuel will likely spill; keep the drain pan positioned. Once the tank is clear of the vehicle, carefully roll the jack and tank out from under the vehicle. Move the tank to a well-ventilated outdoor area away from ignition sources.
10. 10

    Inspect tank mounting area and components
    With the tank removed, inspect the tank mounting area on the vehicle frame for rust, damage, or deterioration of the fiberglass body in the tank area. Inspect the fuel tank straps for rust, cracks, or deformation; replace if compromised. Check all fuel lines, hoses, and fittings for cracks, corrosion, or deterioration. Examine the tank itself for rust, leaks, dents, or damage. Clean the mounting area with a wire brush and remove any debris. If installing a new or cleaned tank, replace all rubber hoses and consider replacing the fuel sending unit and gasket.

Reassembly

1. If reusing the original tank, flush it thoroughly with water and allow to dry completely before reinstallation (at least 24 hours in a ventilated area)
2. Install new sending unit gasket and verify sending unit operation before installation if possible
3. Replace all rubber fuel hoses and deteriorated clamps with new fuel-rated components
4. Raise the tank into position using the transmission jack, aligning it carefully to avoid contact with the fiberglass body
5. Install tank straps and secure with mounting bolts; tighten bolts evenly and securely but do not overtighten as this can deform the tank
6. Reconnect all fuel lines in reverse order of removal, ensuring threaded fittings are tight and hose clamps are properly positioned and tightened
7. Reconnect fuel sender electrical connection
8. Reconnect vent line and filler neck hose with new clamps
9. Double-check all connections for security before proceeding

Verification

• Reconnect battery negative cable
• Add 2-3 gallons of fresh fuel to the tank through the filler neck
• Inspect underneath the vehicle for any fuel leaks at all connection points
• Turn ignition key to ON position (do not start engine) to activate fuel pump if electric, or manually operate mechanical pump if equipped
• Recheck all connections for leaks while fuel system is pressurized
• Start engine and allow to idle; inspect again for leaks with engine running
• Check fuel gauge operation to verify sending unit connection is correct
• Take vehicle for a brief test drive and perform final leak inspection after the drive
• Monitor for fuel odors in the vehicle or near the tank area over the next few days

More procedures for this vehicle