* In-tank pumps (most common in modern trucks): These are usually submerged within the fuel tank. You won't see them without removing the fuel tank. They often have a cylindrical or slightly oblong shape and are connected to a wiring harness and fuel lines. They may have a strainer or sock attached to filter debris.
* External pumps (more common in older trucks or some specialized applications): These are located outside the fuel tank and are usually mounted to the frame or chassis. They might resemble a small canister or box with various fittings for fuel lines and electrical connections. They often have a slightly more industrial appearance.
* Electric pumps (most common): These are powered by electricity and will have electrical connections visible.
* Mechanical pumps (less common in modern trucks): Driven by the engine's camshaft, these are usually less complex in shape, sometimes resembling a small gear-driven device with fuel line connections.
In short: You can't reliably describe the look without more specifics about the truck. If you're trying to locate your fuel pump, consult your truck's repair manual or search online for diagrams specific to your make, model, and year. Pictures online might be helpful as well – search for "[your truck make and model] fuel pump location."
