SL-C Manual: Fuel Tank Installation
The fuel tank should be rubber-mounted or otherwise isolated from the chassis to reduce stress and vibration that can lead to cracks or other failures in the tank and its mounting.
See the photos below of one example of fitting the fuel tank. First is a drawing of a fuel tank mounting tab. The photos show the use of rubber insulated hold down tabs at the top and side of the fuel tank, rubber insulation under the fuel tank and along the front edge, and a rubber insulated aluminum angle running behind the fuel tank.
Fuel Level Sender Mounting
The fuel level sender is easily mounted on the fuel tank.
The top of the tank has a welded-in flange to which the included sender can be bolted. Note there is only one way for the sender to fit, so you may need to move the sender around on the flange to get the holes to line up. Be sure to use the included cork gasket to control leaks. The gasket should be used without any sealants.
If the flange hasn't been tapped, use an 8-32 tap to make the holes. You can minimize the amount of tapping debris in the tank by taping a rag under the flange while tapping. Use 8-32 bolts that are 1.5" long- a little stickout in the tank doesn't matter. You can use Loctite 242 (blue) to hold in the bolts. Torque the sender bolts carefully to no more than 15 inch-pounds, and torque them in a cross sequence as you would a set of wheel lugs. Don't over-tighten these bolts, as that could damage the sender, and ironically, cause leaks.
The sender is designed for the standard Koso gauge and for the profile of the standard fuel tank. A normal GM or VDO sender doesn't work with the Koso, and wouldn't be accurate anyway if it did due to the tank profile. Use the provided sender if you are using the standard Koso gauge.
After the sender is installed on the tank, wire it according to the instructions in the wiring section. Note that the sender requires a ground, the signal wire to the Koso (which is part of the unterminated set of wires in the chassis harness) and a switched 12V line, which can be obtained from the engine controller fusebox, or from one of the unused outputs on the back Powercell. All three wires must be connected properly for the sender to work.