How to Test Fuel Tank Selector Switch?

“Do anybody find a way to test the fuel tank selector switch of my truck?”– it is one of the most asked questions. Many people have faced trouble because of this issue in the middle of the road. So, it is essential to know how to test fuel tank selector switch. If you check after buying it, you will be sure if it is working right. Then you will not face trouble while making your journey.

Many people don’t know the procedures to test the fuel tank selector switch even if they drive well. But every driver should check several things, including this switch before starting to drive. You will know this here step by step. Follow the instructions and test if the fuel tank selector switch of your truck is okay.

Let’s Know How the Tank selector switch is and How It Works

Step 1:

At first, let’s know how the fuel tank selector switch looks. The left side of the tank selector switch is assembled from the tanks, and the right side of the switch is assembled to the engine at the bottom. At the bottom of the switch is like an O-ring in the cup.

Step 2:

Now, to start your testing, you have to take off the top part of it. You will find a rubber diaphragm there.

Step 3:

This diaphragm works on this plate as an up force or as and downforce.

Step 4:

Now, you will find two valves under the plate. The work of these two valves is to direct fuel either from the two tanks or to the two tanks. It depends on the position of the two containers. They may be on the up position or the down position. Here one valve remains half disassembled.

Step 5:

The valves remain attached to the plate. There are different holes in the valves’ body. These valves open when the plate moves. Various valves open as the plate moves up or down.

Step 6:

The big hole is on the upper right side of the valve. Here the fuel enters the cup. Another hole is also at the right side works to make a return of the fuel to the tank valve. The O-ring fits the upside of the valve.

Step 7:

When you keep the rear tank on, it forces the fuel through the hole to the top part of the diaphragm. It will push the diaphragm down and opens the valves from the rear tank to the fuel lines. It will dump fuel into the cup. This, in turn, will feed the high-pressure pump and the engine. It allows the fuel to return the tank.

When the front tank is on, it will force the fuel through the hole below the diaphragm. It pushes the diaphragm up and so; it changes the valve to open the feed of the front tank and the return lines.

These are the description of how the fuel tank is and how it works. Now we are going to know how to test it before starting your use.

Steps Of How To Test Fuel Tank Selector Switch

To test the tank selector switch valve, used terminals that are on the valve are:

Pin-1: not used pin.
Pin-2: 789- BR/W
Pin-3: 786- R
Pin-4: 673- DB/Y
Pin-5: 29- Y/W
Pin-6: 675- Y/LB

Steps to test the rear tank switch are described below:

Step 1: At first, you have to apply 12V power broadly to the terminals 789- BR/W (+) and terminal 786- R (-).

Step 2: Now, you have to connect the self-powered test lamp or the ohmmeter to the terminal 29- Y/W and the terminal 675- Y/LB.

If the tank selector switch is right, then the above action will indicate the closed switch.

Steps to test the front tank switch are described below:

Step 1: At first, you have to apply 12V power broadly to the terminal 786- R (+) and the terminal 789- BR/W (-).

Step 2: Now, you have to connect the self-powered test lamp or the ohmmeter to the terminal 29- Y/W and the terminal 675- Y/LB.

If the tank selector switch is good, then the above action will indicate the open switch.

At last, you must check if the sources and the return valve can transfer between the front and the rear positions. You may want to know how you can confirm about this transference. Well, you have to try to hear sound while transferring is happening. You will listen to a zip sound if the valve transfers.

Conclusion

If you do not know totally about the components of your truck and how to test those components, then you should not go for driving. Because you may fall for any troubles for not working well on these components. Your car may be down in the middle of the road. Then what will you do?

So, only knowing a skilled driving is not enough.

We should know about the components of your car or truck. The fuel tank selector is also an important component. You should see this switch briefly. If you follow this article, you will know every detail part of the fuel tank selector switch and you will know how to test the fuel tank selector switch valve step by step. So, be careful and check your truck components before driving.

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