[mcdett]

An engine oil pressure switch is used to maintain power to the engine, and the vehicle, once the engine has started. When the engine is cranking, power is being supplied through the starter circuits. However, once the engine is running, and the oil pressure is up, power is routed through the oil pressure switch and sensor unit. This is done to ensure the engine is not run without oil. If the sensor does not read the right pressure, the switch will not close, and the vehicle will not stay running. [links]

[martin]

here

[chariottrading]

[Xobbit]

[links]

[diven]

[brettpearson6]

more

[nfawlaltorynog]

Fuel Pump Relay Diagnostic/Troubleshooting Notes:

[franklions99]

Fuel Pump Relay Diagnostic/Troubleshooting Notes:

[insert]

NOTE: The illlustrations and info in this page apply only to 1994 Chevrolet/GMC pickups with a 4.3L, 5.0L or a 5.7L engine. For the 1993 fuel pump wiring diagram, check out the following article:

[destinbrides]

Engage the parking brake to the lock the rear tires from moving. more

[bitcoinia]

Step 4: Open the vehicle’s hood to disconnect your battery. Take the ground cable off of the battery’s negative post disabling the power to the fuel pump and sending unit. more

[ptime]

Step 4: Start the engine. Start the engine up and check to make sure that the engine will stay running.

[LobsterMan]

Step 1: Reconnect the battery. Reconnect the ground cable back onto the battery’s negative post. [links]

[mtve]

For custom applications, regardless of the style of pump you choose, you need to know what size to get. While the old penchant of bigger is better is often true, there are situations where too much fuel pump can actually cause problems. A fuel pump is designed to move fluid and build pressure. A typical carburetor requires 7-14 psi of fuel pressure to ensure the bowls stay full. EFI systems require wildly different pressure, but typically range from about 26 to 60 psi, more with boost. [links]

[annedubois]

Diaphragm pumps use a composite membrane, which flexes up-down over a fuel bowl. The bowl has an input and an output, each with a check valve in place to ensure a one-way motion of fluid. As the diaphragm moves up, it creates a vacuum, pulling fuel from fuel tank into the fuel bowl. The actuating lever then pushes the membrane down, pushing the fuel out at pressure, which for carbureted engines is about 6 psi. Older carbureted engines use mechanical diaphragm pumps almost exclusively, and some of the cheaper aftermarket electric pumps use this style as well. Diaphragm pumps are simple in form and function, they last for years and years. Even when left to sit for 20 years, a diaphragm pump will usually still work once it gets a fresh hit of fuel.

[Ricochet]

There are numerous components inside your car that are rarely given a single thought, parts like the brake booster, radiator thermostat, or the fuel pump. These parts are hidden away, doing their job until the day comes that they don’t. That is when those parts quickly become a burden. The fuel pump is one of those critical components that is forgotten right up until it dies, and of course, when a fuel pump goes bad, it just goes, there is rarely a warning. Fuel pumps are typically not rebuildable (some aftermarket pumps are, but stock ones are not), so replacement is the only option. Most newer vehicles will get a factory replacement pump and that is the end of it, but for older vehicles and modified cars, there are some options. Fuel pumps come in three main flavors; diaphragm, rotary vane, and gerotor. Each has pros and cons to their design.

[marrypires12]

Rotary vane pumps typically are used for low pressure applications and are almost in the T-style configuration (motor on top, inlet/outlet on the bottom), while a few are inline sliding vane pumps. High-performance and high-pressure applications, need a roller vane design. While sliding vane pumps have high friction on the vane edges, the roller design uses a rolling bar, eliminating the friction. This style of vane is more suited for high pressure, and are more efficient. Dirty fuel is a big issue for all rotary vane pumps. Dirt increases wear on the paddles and pump housing, reducing pressure output.

[danknug]

Because the pump is mounted to the block and runs off the camshaft, the pump only produces what the engine needs; there is no need for a return line from the fuel rails. The mechanical pump is fed by an electric lift pump. This is the same for both direct-injection gasoline engines and diesel engines. High-performance GDI (the term used for Gasoline Direct-injection) engines require some alteration when boosting power. Comp Cams now makes tuned cam lobes for the Gen V LT1 series GM engines, so you can boost your fuel output to match that new supercharger, and big-bore mechanical pumps are becoming available as well. here