S30 Fuel Tanks

Tank Versions

Production dates and shapes from S30.world (see Sources). They're production months, not model years, so a car built near a change can have either tank.

Capacity

From the "Approximate Refill Capacities" table in section GI of the 1973, 1975, 1977 and 1978 factory service manuals. The 1977–78 tank is a new shape, but the factory lists the same 65 liters as the 1975–76 tank. The fuel warning lamp comes on with about 10 liters (about 2 1/2 US gallons) left.

Vapor vs Non-Vapor

A vapor tank is part of the evaporative emissions system. Instead of venting fuel vapor to the air, the tank has extra vent fittings on top that connect by breather hoses to a vapor reservoir tank behind the rear quarter trim, and from there a vent line runs forward to a carbon canister in the engine compartment that stores the vapor until the engine burns it. A non-vapor tank doesn't have those vent fittings.

Every U.S. and Canadian car from early 1970 on has a vapor tank. Fitting a non-vapor tank to one of these cars leaves the vent lines with nowhere to go, so buy the type that matches your car.

Identifying Your Tank

1. Start with the build date on the door jamb or VIN plate, and the market the car was built for, then use the table above.
2. Look at the top of the tank (you may need to lower it a little): rounded or square corners, a cross-shaped or full-width stamping, or a raised section.
3. Count the vent fittings to tell vapor from non-vapor.
4. Check the outlet size. The fuel injected 280Z uses a 10 mm outlet; carbureted cars use an 8 mm line, so a 10 mm tank on a carbureted car needs a 10 mm to 8 mm reducer.
5. 1977–78: if the car has the raised hatch floor and space-saver spare, it has the late tank. It won't fit an earlier car, and an earlier tank won't fit it.

Remember the car may not have its original tank. Swapped tanks are common, so check what's actually there before you order parts. See S30 Model Year Differences for the other year-to-year changes.

Removal and Installation

The factory procedure for the 280Z (FSM section FE):

1. Disconnect the battery ground cable.
2. Remove the drain plug from the bottom of the tank and drain all the fuel into an approved container.
3. Disconnect the sender wire, the fuel outlet hose and the fuel return hose.
4. Remove the nuts from the two tank straps and lower the tank slightly.
5. Disconnect the three vent hoses that go to the reservoir tank, and the filler hose, then lower the tank out.
6. Plug every hose and tube opening so dirt can't get in.
7. Install in reverse order. Install the filler hose after the tank is mounted, or it can leak at the connections. Don't kink or crush the breather hoses, and clip them securely.

Fuel Sender

• The sender (Nissan calls it the tank unit gauge) is a bayonet fit. Drain the tank, disconnect the wire, and turn the sender counterclockwise to remove it.
• When you reinstall it, line up the tab on the sender with the notch in the tank, use the O-ring, and tighten it securely.
• The sender also carries a thermistor for the low fuel warning lamp. Sender testing is on the S30 Sensors page.

Common Problems

• Rust inside the tank. Old fuel and water leave rust and varnish that clog the outlet, filters and injectors. A tank can be cleaned and sealed, but a badly rusted one is better replaced.
• Rust outside. Mud and water sit on top of the tank under the spare tire well. Check the top and the strap areas for rust-through, and the area of the body above it.
• Internal filter (1977–78). The late tank has a filter inside it, which clogs with age and starves the engine of fuel. Some reproduction tanks leave it out and use an external filter instead.
• Vent hoses. The small breather hoses to the reservoir tank crack with age, causing a fuel smell in the hatch. Replace them with fuel-rated hose.
• Filler hose. The large filler neck hose also cracks and leaks fuel when the tank is full.