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Old Sep 7, 2016 | 09:04 AM
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Rob Longson's Avatar
Rob Longson
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Joined: May 2016
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From: Bedfordshire
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just found and read this article and it does seem to match the symptoms i am experiencing

The Electronic Fuel Pump

Although the mechanical fuel pumping system was always sufficient for carburetor-based fuel systems, eventually vehicle manufacturers moved past the use of carburetors in favor of a more advanced fuel injection system. Although the fuel pump itself is still necessary, the mechanical pump cannot generate the level of pressure needed to work with fuel injection engines. Therefore, a new system that delivers gas or diesel under high pressure, such as between 40 and 60 psi, was created. This system is what is known as an electronic fuel pump.
Nowadays, most vehicles use an electronic fuel pump, which is located within the gas tank itself, to deliver gas or diesel. There are far more inherent issues with electronic fuel pumps. The electronic system works by spraying a fine mist of fuel inside the engine's chambers and is operated through a computer control system rather than a mechanical one. As a result, both issues with the pump itself as well as the computer used to operate it can lead to malfunction and breakdown.
Remember, the purpose of a fuel pump is twofold:
  1. It pushes or pumps fuel from the gas tank to the fuel injector or carburetor.
  2. It creates the proper amount of pressure to ensure that the right amount of fuel will be delivered to the engine, regardless of external conditions.
Therefore, malfunctions in the fuel pump can result from an issue in either one of these processes. Let's take a look at the common signs of these problems.
1. The Engine Sputters at High Speed

The most common early sign of a problem comes when driving a vehicle at a consistently high speed. While traveling down the road, the car will run well for about 10 miles and then begin to jerk or sputter before returning to normal.
What This Means

Many members of the driving community at times will mistakenly diagnose a sputtering vehicle as one with "dirty" gas, an almost empty tank or some other fuel-related issue. While that can be the case, it is not uncommon for a fatigued fuel pump to create this same symptom as it struggles to supply a constant stream of fuel to the engine at the proper pressure. The loss of pressure causes the engine to sputter.
2. Vehicle Loses Power While Accelerating

With a similar symptom to the previous, vehicles will jerk during acceleration from a stop. The car may produce a stalling sound and then accelerate smoothly.
What This Means

Once you take your foot off the brake and hit the gas pedal, a working pump increases the flow of gas or diesel to fuel acceleration. Because a malfunction starves your car of that increased flow, it doesn't have the power it needs to respond to commands. Once pressure is restored, the engine is able to run smoothly, and the car takes off.
3. Sudden Loss of Power When the Vehicle is Under Stress

A car or truck is put under stress when the work needed to complete an ordinary task, such as forward movement, is somehow hindered by external forces. Generally, this occurs when climbing a hill or when hauling a load. If, when completing these tasks, the vehicle loses power, cannot accelerate, or begins to sputter, the fuel pump is a possible culprit.
What This Means

Generally, even an aging pump can maintain a steady stream of fuel and pressure when operating under normal conditions. These devices create resistance or fail when under stress, leading to power loss.
4. Surging

If your vehicle doesn't lose power while driving, you may find it surges - accelerating suddenly with no drive input.
What This Means

Some may mistakenly blame this on the fuel filter, reasoning that it is not properly trapping dirt and rust. More likely, this surge is created because, as a result of age and normal wear and tear, the fuel pump has irregular resistance within its motor. This creates a situation where the pump cannot draw enough electricity to maintain the pressure needed for steady speeds and may "surge" with a sudden ratcheting up in pressure.
5. The Engine Will Not Start

The final symptom of a malfunctioning pump is also the most severe. Drivers who ignore the signs eventually will end up here, with a car or truck that won't start.
What This Means

When a pump has malfunctioned to the point that the car will no longer start, this means that there is no fuel reaching the engine upon ignition. For that reason, drivers will hear the sparks try to ignite, but there will be no fuel to burn. To diagnose such a malfunction, check for a blown fuse and pressure in the fuel line, as the gauge should read 0.
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