How To Test A Diesel Injection Pump: 2 Simple Ways

Do you know how to test a diesel injection pump? Checking the fuel filter or bleeding the fuel, you can check it easily.

Testing a diesel injection pump is one of the simplest ways to test your engine. Diesel injection pumps are among the essential components of a diesel engine.

To ensure that the engine functions correctly, it is vital to check the working condition of the injection pump. Have nothing else to worry about.

In this article, we will provide 2 straightforward techniques to evaluate your diesel injection pump and ensure that it continues to operate at peak performance and reliability.

How To Test A Diesel Injection Pump

Testing a diesel injection pump is not a difficult task. You can quickly test a diesel injection pump by following some simple steps. If you want to know how to test a diesel injection pump or how to test a mechanical diesel injection pump, then check the below two easy methods.

Method 1: Testing By Checking The Fuel Filter

If you have a 2002 Chevy GMC 6.5L engine and want to know how to test the injection pump on 6.5 diesel, then you should follow this method. Let’s see all the steps below.

Step 1: Open The Fuel Filter Bleeder

Firstly, start your vehicle. You need to open the fuel filter bleeder until fuel comes out during your vehicle cranking in short bursts. After that, close the fuel filter bleeder.

Step 2: Check The Fuel Filter

Next, check whether fuel comes out from the fuel filter or not. If there isn’t any fuel coming out from the fuel filter, the lift pump is most likely faulty.

Step 3: Dismount The Output Side Of The Lift Pump

After step 2, in this step, dismount the output side of the lift pump and check if you get any fuel during cranking. The output side of the lift pump is mounted on the passenger side at the front bottom of the block. If you don’t get any fuel, then replace the lift pump.

Method 2: Testing By Bleeding The Fuel System

Let’s see how to test a diesel injection pump or how to test a diesel fuel injection pump by bleeding the fuel system.

Step 1: Remove The Injectors

In this method, you need first to remove the injectors from your engine. Then, you have to connect the steel fuel line with the injectors. Ensure that the injectors are facing away from your vehicle’s engine when connecting the steel fuel line.

Step 2: Bleed The Fuel System

Now, you need to bleed the fuel system. To do that, firstly, fill the tank to its complete with fuel. It will aid in adding pressure to the fuel system and clean the air considerably quicker. Now, find the bleeder screws located at the topmost of the fuel filter valve.

Then, you need to open the left screw at the topmost by doing a few rotations and wait for the fuel to finish coming out. When no more bubbles are coming out, you must stiffen the screws back up. After that, do the same with the screws on the right. It will signify that the fuel filter is filled with fuel.

If you didn’t fill the tank, there wouldn’t be generally sufficient pressure to force the fuel via the fuel filter. Make sure that you don’t over-tighten the bleeder screws as they are pretty small screws with holes in them and don’t take much to twist them off. Next, you need to follow the fuel hose to where the injection pump is.

You would find a small bleeder screw there on the injection pump where the fuel line enters inside the injection pump. Loosen the bleeder screw and then wait for every air bubble. Finally, tighten the screw, and now you will be getting the fuel to your injectors straight.

Step 3: Turn Over the Engine

In this step, crank the engine to turn over. Then, let the fuel bleed out on a paper or cardboard.

**Note: Keep in mind that the fuel bleed out of the injector at around 3,000 pounds per square inch (PSI). If the fuel split on you it might hurt your skin severely. So, stay away!

Step 4: Check The Pattern On The Board

Finally, check the praying pattern on the paper or baord.

The diesel injection pump is good if you have a good round mist type shape. However, if the spraying fuel pattern is irregular or the fuel bleed is found squirts, the injection pump has  issues and might need a new injector.

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Frequently Asked Questions (FAQs)

How do you diagnose a bad diesel injector pump?

You can diagnose a lousy diesel injector pump in many ways. The first thing you need to check is an engine sputter, especially at a higher vehicle speed. You also need to check an engine sputter while accelerating your vehicle. You need to check the smell of fuel inside the car, as it can lead to fuel leakage. Finally, check whether the exhaust is dirty and the emission of white smoke..

How do I know if my injection pump is bad?

Your injection pump can be harmful if the low diesel injection pumps pressure. So, you need to know how to check diesel injection pump pressure. To do that, firstly, remove the injector out of the engine. Then, start your vehicle and let it idle. After that, install an injection pump gauge and run the pump. You need to note the pressure reading and compare it to your vehicle’s manufacturer’s specifications.

Final Verdict

When it comes to testing a diesel injection pump, the more specific the method is much better. Thus, the article addresses how to test a diesel injection pump. Keep in mind that you can use it to determine if your engine is running correctly during these tests. But they are not 100% accurate.

There are several ways to test a diesel injection pump, and it is vital to choose the correct test for the job. We’ve demonstrated two of the most efficient and reliable methods for testing a diesel injection pump. So, pick whichever of these two approaches works best for you. If you can’t do it on your own, don’t hesitate to get in touch with an expert.

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Ronald Berit

Our chief editor, working 24/7 to ensure the precise and only quality data regarding different trucks.He is mastered with the ins and outs of cargo to off-road trucks of Dodge, Ford, Chevy, Toyota, GMC and more. This truck geek graduatedwitha Bachelor of automobile engineeringdegree and practiced through his own automotive parts repair center.

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