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How to Use a Fuel Pressure Gauge Accurately?

Some stubborn cars will not start no matter how hard you try. You press the engine start button or turn your keys no matter how many times;it will not budge.

Now a car won’t start due to a lot of reasons. It can be issues related to the fuel or the fuel pump. There might even be instances where the injectors might not be getting enough fuel pressure.

How do you determine what is causing the problem?

The simple answer is a fuel gauge tester. While a fuel gauge or pressure tester might have your answer, it’s important to ensure that the test is conducted properly.

Here is a step-by-step guide on how to use a fuel pressure gauge accurately.

Overview of Fuel Pressure Gauge

Before getting into the details of accurate measurements, let’s first get an overview of the fuel pressure gauge. Fuel is one of the key elements of running an engine. As a result, whenever an engine fails to start, it almost always has something to do with fuel-related issues.

While it may sound like a hefty task, measuring the fuel gauge accurately is very easy. And it all starts with knowing the basics.

The gauge itself is a dial that displays the pressure in psi. All you have to do is connect the gauge with the fuel pipe and some other fittings. It is a one-person job and can be done sitting on the steering wheel. What’s important is to understand what good fuel pressure is.

There is no direct answer to this. It will vary from engine to engine. In the last couple of decades or so, engine technology has changed drastically. With more and more fuel-saving technology and power efficiency, the pressure limit has also changed almost drastically.

An LT1 V8 engine should gush out pressure ranging between 40-42 psi, whereas a similar LS1 V8 should have a 58 psi. It all depends on the engine and can be easily located from the included repair module.

Steps to Use Fuel Pressure Gauge Accurately

Before starting, always perform the test in an open area since fuel vapors are highly flammable.

Now, follow the simple four steps below to get the perfect reading from the pressure gauge.

Step 1

Make sure the engine is cold. Open the hood and locate the Schrader valve fitting. It is usually found on the fuel rail. Most modern cars tend to hide the Schrader valve under the rail cover. In that case, pop opens the rail cover or the engine cover.

Step 2

In the second step, you have to remove the Schrader valve. After that, connect the fuel gauge connector to the valve. Make sure the fitting is airtight.

After that, get into the driver’s seat and turn on the ignition. Make sure just to “On” the ignition and not full-blown start. Then check the psi reading on the gauge. If there is a drop in the psi level, understand that there is a leak in the engine fuel system.

However, the job isn’t done just yet. Check for the same after 10-15 minutes. If the level holds, that means the engine is capable of holding the pressure.

Step 3

Check the psi reading after 15 minutes. If there is any drop in the psi reading, it is an indicator that the engine is losing pressure. If there is any external dripping, it means the leak is happening internally within the engine.

Step 4

After that, start the engine, and check whether the pressure is within the recommended limit. If so, then the engine issue is not related to pressure faults and it might be something else.

What do Fuel Pressure Readings Indicate?

Measured the psi reading of your engine?

Congratulations that is half the job done.

Now it is time to interpret what does the readings mean. For ease of understanding, we will break it down into several sections.

  • Zero Fuel Pressure

This means the pump is completely dead that it cannot provide any pressure to the engine. The first thing you should do is check for the fuel pump fuse. A multimeter will help ensure if there is adequate power or not. If not, then it is time to get the fuel pump replaced.

  • Low Fuel Pressure

Low Fuel pressure means that the fuse isn’t completely fried. There might be minor issues with the pipe, like clogging or return line failure. In that case, simply get the individual issues fixed.

  • High Fuel Pressure

High fuel pressure occurs because of clogging on kinking of the return fuel line. It is almost always either of these two. Just get the return line unclogged, and you are good to go.

Final Thoughts

That should solve your fuel pressure issues. It is crucial to get the testing right with the fuel gauge. As you may have noticed, a correct reading makes all the difference while interpreting the pressure level. It might reveal severe issues regarding the engine and the fuse. So, make sure you follow the steps properly.

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