Car's Fuel Pump Fails: Understanding The Role Of The Oump Fuse

The fuel pump in a car will still run with the fuse pulled, but at lower fuel pressure. The fuel pump gets a secondary voltage from the oil pressure sender, so even if the fuse blows, the pump will run if you have adequate oil pressure.

Car still runs without fuel pump relay

If your car will run with the fuel pump relay bypassed, then the fuel pump is fine. If the relay is fine, then the control for the circuit has a failure. Most of the time this is caused by an issue with the ignition switch or the vehicles main relay. Typically it is the ignition switch though. You would usually start by doing a voltage drop test of the ignition switch followed by testing the main relay.

The main fuel pump relay is in the main fuse box, behind the battery (in the stock location) and to the driver's side of the engine. It should be a large green relay, labeled "EFI" on the cover, if I'm not mistaken. Pull that relay and start the engine and it will run momentarily, sputter, and die, depressurizing the fuel line and ensuring that no fuel is delivered to the engine. This is the relay you want to pull if you ever do a compression test on the engine, or have to replace the fuel pump or fuel filter.

The fuel pump will still run through the fuel pump resistor with the relay pulled, albeit at lower fuel pressure. I don't remember the schematic off the top of my head but I remember it is possible.

The relay in the front-mounted relay box (labeled "Fuel Pump Relay") is actually the relay for switching from ~9.6 volts to the fuel pump to a full 12+ volts under WOT.

If you pulled the wrong relay, but it was an honest mistake, then the car will still run.

Adequate oil pressure keeps fuel pump running

Adequate oil pressure is essential to keep the fuel pump running. The fuel pump gets a secondary voltage from the oil pressure sender. Even if the fuse blows, the pump will run, if you have adequate oil pressure.

The main fuel pump relay is in the main fuse box, behind the battery (in the stock location) and to the driver's side of the engine. The fuel pump speed relay, not the main fuel pump relay, is the relay you want to pull if you ever do a compression test on the engine, or have to replace the fuel pump or fuel filter.

The fuel pump will still run through the fuel pump resistor with the relay pulled, albeit at lower fuel pressure.

The fuel pump fuse should die without the fuse, but can't you just unplug the pump itself. It's only like 4 or so bolts to pull the cover by the filler neck then just unplug the electrical connector there. The other option is: make sure the car is completely COOL, then get a rag, wrap it around the Schrader (sp?) valve on the fuel rail and push the needle. Gas will come out but with a cool engine and a rag you shouldn't make to much of a mess.

Fuel pump resistor keeps fuel pump running

The fuel pump resistor is a component that keeps the fuel pump running by providing a secondary voltage to the fuel pump from the oil pressure sender. This allows the fuel pump to continue running even if the main fuel pump relay is pulled or the fuel pump fuse is blown.

The fuel pump resistor is typically located in the main fuse box, behind the battery and to the driver's side of the engine. It is important to note that the fuel pump resistor is different from the main fuel pump relay, which is responsible for controlling the fuel pump at a higher level.

If you are experiencing issues with your fuel pump, it is recommended to check the fuel pump resistor and ensure it is functioning properly. This can be done by testing the resistor with a multimeter or replacing it if it is faulty.

In addition, it is important to note that the fuel pump resistor is not the only component that can affect the fuel pump's performance. Other factors, such as low oil pressure, clogged fuel lines, or faulty fuel injectors, can also cause the fuel pump to malfunction.

If you are experiencing issues with your fuel pump, it is recommended to have your vehicle inspected by a professional mechanic to identify the root cause of the problem and ensure that it is resolved properly.

Car still runs without fuel pump fuse

The fuel pump will still run through the fuel pump resistor with the relay pulled, albeit at lower fuel pressure. The car will continue to run with this relay pulled. The main fuel pump relay is in the main fuse box, behind the battery (in the stock location) and to the driver's side of the engine. The fuel pump gets a secondary voltage from the oil pressure sender. Even if the fuse blows, the pump will run, if you have adequate oil pressure. The fuel pump fuse is after both the pump relay and oil pressure switch. It should die without the fuse, but can't you just unplug the pump itself. It's only like 4 or so bolts to pull the cover by the filler neck then just unplug the electrical connector there.

Fuel pump gets secondary voltage from oil pressure sender

The fuel pump gets a secondary voltage from the oil pressure sender. This means that even if the fuse blows, the pump will still run if you have adequate oil pressure.

The main fuel pump relay is in the main fuse box, behind the battery (in the stock location), and to the driver's side of the engine. The fuel pump speed relay is not the main fuel pump relay.

The fuel pump resistor is the relay you want to pull if you ever do a compression test on the engine, or have to replace the fuel pump or fuel filter.

The oil pressure sender is the fuse that is after both the pump relay and oil pressure switch.

The fuel pump fuse is after both the pump relay and oil pressure switch.

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