The answer is no. Fuel pumps aid your fuel systems, but can you drive your car without a fuel pump, read along as I will answer the question below.
If you have discovered damage to the fuel pump, you can continue driving the vehicle for a while, but the car may no longer start at some point.
For this reason, if you suspect a defective fuel pump, you should visit a workshop as quickly as possible or, if you feel capable of changing a pump yourself, do this as soon as possible.
To properly understand this subject, we need to understand the role of the fuel pump in internal combustion engines before we can conclude whether it is possible to drive without it.
The fuel pump feeds the petrol or diesel engine through the injection pump or the nozzle. The fuel pump can be electric or manual.
Then the whole is integrated into a module submerged in the tank. The fuel is drawn into an inlet pipe after passing through a prefilter and forced through the outlet pump.
The module consists of a motor, a gear pump, a pressure damper, and an exhaust valve to prevent overpressure damage.
It operates at a constant pressure, typically 2-3 bar, to allow optimal fuel distribution to the engine without interruption and prevent air entry.
For diesel systems, the role of the fuel pump is to deliver the fuel needed for the high-pressure pump.
The high-pressure fuel pump can suck diesel fuel from the tank. It is essential that the high-pressure pump continuously receives diesel to maintain the required pressure.
Considering the role of the fuel pump, we can conclude that a car cannot work without a fuel pump.
But how much pressure is normal for the fuel pump to discharge? Keep reading below
How Much Fuel Pressure Is Normal
A fuel pump must deliver the correct fuel to meet fuel flow and pressure specifications. If the pressure is too low, the engine will not get fuel, run lean, misfire, stall, or stall.
If the pressure is too high, the engine can run rough, use too much fuel and become contaminated.
Before you diagnostically check the fuel delivery system, you must know what fuel system is in the vehicle.
Closed-loop and opened-loop fuel systems have similar components. However, the location of these components will dictate how the fuel delivery system operates and, consequently, what diagnostic tests must be performed.
Before testing, ensure the battery is fully charged (minimum to 12.6 VDC). An additional power source may be necessary to maintain the battery voltage at the required level.
Do not exceed 10 seconds of cranking time when starting the engine to avoid overheating the starter circuit and other components.
Test method of automobile fuel pressure:
1. Turn on the ignition switch (do not start the engine) to make the electric fuel pump run. At this time, the fuel pressure should meet the technical requirements. Generally, it should swing around 0.3MPa.
2. Clamp the fuel return hose. At this time, the reading of the fuel pressure gauge is the maximum fuel supply pressure of the fuel pump.
3. Loosen the fuel pipe clamp, restore the static fuel pressure, remove the jumper wire of the fuel pump relay to stop the fuel pump, and wait for 5 minutes.
At this time, the reading of the fuel pressure gauge is the maintenance pressure of the fuel supply system, which should meet the vehicle model’s technical requirements, which are about 340KPa.
The normal range of fuel pressure is between 300kpa and 350kpa. Depending on the model, the gasoline pressure will also be different.
Generally, as long as it is around 300kpa, it is normal. The fuel pressure regulator is a special term in the automotive industry, and it is one of the common components of the fuel injection system of electronic fuel injection vehicles.
There is a diaphragm inside the fuel pressure regulator, which controls the opening and closing of the pressure valve.
When the oil pressure is lower than a certain value, the pressure valve is closed, and the fuel pump increases the pressure in the fuel circuit.
The diaphragm opens, and the overpressure fuel flows back to the fuel tank through the fuel return line, which acts as a decompression.
The Normal Bar For Common Rail
Common rail direct fuel injection is a direct fuel injection technology for gasoline and diesel engines.
For diesel engines, with fuel pressures up to 1,800 bar or 180 MPa or 26,000 psi, the high-pressure common rail uses a single solenoid valve to supply fuel directly into the engine cylinders while the engine is running.
The third generation of common rail technology uses higher precision piezoelectric technology, and the diesel engine fuel pressure can be as high as 3,000 bar (300 MPa; 44,000 psi).
The gasoline engine uses gasoline direct injection technology, and its fuel pressure is generally between 100bar and 200bar
Why Fuel Lift Pump Fail
The general causes of a defect can be dirt inside the pump or a leak. In the case of mechanical pumps, broken diaphragms or a broken pump lever also come into consideration.
With electric pumps, defective power contacts or relays, broken wires, and blown fuses are the most common causes.
Another cause of lift failure is moisture in the fuel tank. Moisture settles to the bottom and oxidizes the metal, causing rust.
The pump has a 70-micron screen which is too large to keep moisture and rust from getting in.
The reason for its size is to allow enough fuel to enter to produce the high pressure associated with electric fuel pumps.
A smaller micron screen would not be practical due to the size needed to allow such flow.
The manufacturer uses the 70-micron screen as a sufficient midpoint for clean fuel. A 30-micron in-line filter traps sediment before it reaches the injectors.
Injectors also typically have an internal filter in the 5-10 micron range to filter out even the smallest sediment.
If a pump fails from contaminated fuel, the fuel screen is discolored on examination.
If you find that the fuel has been contaminated, you must drain the fuel tank and clean it before replacing the pump, or this problem will transfer to the new pump.
Another factor in fuel pump failure is the voltage drop before the pump. It works at total capacity when supplied by 13.5 volts, which a good alternator provides with the engine running.
If the voltage drops to 0.5 volts, the performance starts to suffer.
The main concern is the pump flex cable at the bottom of the pump cap connector. The hook connector under the top of the pump cover corrodes and bows, destroying fasteners. It can only be verified by removing the pump from the vehicle as it is under the cover.
Most new fuel pumps have a new flex cable to prevent this from happening. Always install this new cable when installing a new pump.
If the flex cable has a black powdery substance around it at the connector and the fasteners are burnt, replace the flex cable to restore the necessary tension.
Lastly, the fuel pump fails when a wire separates due to overheating or an open or internal short.
The pump may have failed on its own, or the vehicle ran on so little fuel that it overheated.
Fuel cools the pump, and continuous operation with extremely low fuel levels can overheat the pump.
Fuel pump circuit
The fuel pump has a fuse and relay under the hood. Most vehicles are located in the center of the fuse and relay in the driver’s side fender.
The engine management computer turns the pump on and off. The computer turns the pump on for 2 seconds to power up.
If you don’t see increased crankshaft sensor signals indicating that the engine has started, you’ll turn off the fuel pump. Each time the faucet cycles, the pump will turn on for 2 seconds and turn off.
The injection pump, diesel, and gasoline, like any element of our engine, finally end up breaking or deteriorating with use and time.
The importance of fuel pumps in internal combustion engines can never be overemphasized. In conclusion, you can now see that you can’t drive with a failed fuel pump.