Today's vehicles are designed with an electronic fuel injection system (EFI) that ensures the right amount of gas is delivered to each of the cylinders. It prevents starting problems as well as engine-related issues, such as stalling during idle, misfiring, and a lack of power during acceleration.

As with all components, however, time and use will slowly take their toll. The individual parts of your fuel system will perform less effectively, and eventually, may fail altogether. When this happens, you'll experience one or more of the issues mentioned.

The goal of this article is to help you identify problems that are preventing your fuel system from working properly. Because there are so many parts that can affect this system, we'll focus primarily on diagnosing a "crank, but no start" problem. We'll also assume the other two pieces of the combustion equation - compression and ignition - are fine.

Troubleshooting A No-Start Problem

Suppose you turn the key, and hear your engine cranking. Unfortunately, it fails to start. Assuming the problem is fuel-related, it can usually be traced to one of a few root causes. First, there may be too little pressure in the system; second, one or more of the fuel injectors may be failing to work properly; third, the fuel pump might be malfunctioning; and fourth, the fuel filter may have become clogged, preventing fuel from flowing to the injectors.

Assuming the fuel pump is working fine, turn your attention to the pressure level in the fuel system.

Testing Pressure In The System

Your vehicle requires a certain level of fuel pressure for the engine to start. It varies by make and model. If the assembly cranks, but is refusing to start, there's a good chance the pressure has declined below the necessary level. The challenge is figuring out the reason it has happened.

There are several pressure tests you can perform on different parts of your fuel system. For example, a fuel volume test will help determine whether there is a sufficient volume of gas in the supply line. The pump may work fine, but still fail to move enough fuel into the line.

You can also perform a static pressure test. This will reveal whether the fuel pump is weak, even if it is working. The test can also reveal if the supply line is clogged by something, preventing gas from reaching the injectors.

Another test will assess whether the fuel pressure regulator (FPR) is working properly. The FPR sits in the supply line between the gas tank and engine. It helps manage the pressure in the line, and makes modifications based upon the load placed on the engine. If the regulator fails, the pressure will disappear, starving your engine of fuel.

Replacing The Fuel Pump

Let's assume you have narrowed the problem to a failing fuel pump. In most vehicles, this component is installed inside the gas tank. You'll need to remove the tank in order to remove the pump. Make sure you disconnect your battery prior to doing so.

With the tank removed, open it up and inspect inside. Note any signs of rust that may have accumulated. Also, take a look at the filter screen on the pump to check whether dirt and other debris have been caught inside. If so, this may be the reason for the lack of pressure in the fuel line. Install the new pump, reinstall the fuel tank, and reconnect your battery. Assuming the pump was the problem, your engine should not only crank, but start easily.

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Author: Lawrence Reaves

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Diagnosing Problems in Your Car's Fuel System
By Lawrence Reaves
The easiest component to check is the fuel pump since it makes a distinct sound when it is working. Lift the hood of your car, and have someone crank the engine while you listen for the pump. If you hear nothing, it means the part is not working properly. This may be due to a faulty relay, or the pump itself may have failed.
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