5 Symptoms of Bad Fuel Tank Selector Valve You Should Know

As large Ford vehicles and other big rigs use more than one tank for storing more fuel, it requires a fuel tank selector valve. 

It regulates the flow of oil in the main tank and secondary tank to meet the fuel demand by the engine.

Like any other part, it can go bad. knowing the symptoms of a bad fuel tank selector valve can help you solve problems right away. 

Signs of A Bad Fuel Tank Selector Valve

Having no fuel in the other tank and overfilled tank with fuel are the obvious signs of a bad fuel tank selector valve.  

Some owners also mention a non-responsive selector valve during the start. 

But the valve can fail in different ways and show various symptoms. 

What Are the Symptoms of a Bad Fuel Tank Selector Valve?

As I have said there are lots of different situations, you have to know how to detect a bad fuel tank selector valve. 

Here, I have discussed all probable symptoms to help you take action without any delay or causing more damage. 

1. Fuel Tank Not Functioning

With selector valve issues, a common symptom is improper functioning fuel tank (both bolt and unbolt). 

In this case, one should check the selector valve switch and wire. Also, don’t forget to inspect the small motor. 

In some cases, any type of damage in the valve switch causes this issue. You should attend and take care of the problem without any delay.  

2. Fuel Circulation Problem

Besides non-functioning fuel tank problems, owners also face poor fuel circulation issues. 

A faulty selector valve causes the switch to fail to result in rear tank blockage. That is why fuel can’t go through the front tank.

3. Only One Tank Operational

That is right. When the selector is not functioning properly, the switch can’t do its job. As a result, one tank keeps working and the other does not. 

Checking the valve switch can expose where the problem lies. Sometimes, the wire is loose, or a faulty small motor is a culprit.

From the dashboard signs, you may think that no fuel is present. If you think that the mileage is not satisfactory, check the secondary tank.

Seeing fuel in there means that the tank selection mechanism needs a thorough inspection. 

4. Not Responding During Start

According to the used Ford owners, it is common to experience a non-responsive selector valve. 

Some even complained that their vehicle had it missing. In either case, you have to replace or install a new one for proper functioning.

5. Overfilled with Fuel

So far, I have talked about issues with no fuel. But a bad valve can cause overfilled primary tank.

As the switch fails to open at the right time, it overfills the primary tank. The issue also includes symptoms like leaking fuel tanks. 

In this case, experts recommend not to rebuild the valve but to replace it immediately. 

What to Do When You Detect A Bad Fuel Tank Selector Valve?

All symptoms discussed above can also be caused by other factors. The first thing to do is check the valve and know whether it needs replacement or not. 

Here, let me tell you the steps to check it without any expert help.  

  • Firstly, turn on the ignition switch, disconnect the selector valve from the feed wire. Then, connect a 12V test light placing in-between ground and wiring harness terminal.

Tip: Here, you have to place the switch of fuel selector on the rear for ‘F’ models and the front for ‘E’ series vehicles. 

  • Now, see whether the light comes or not. Check the fuse block. Also, inspect the fuel valve circuit and valve in case of a blown fuse. 
  • Those who are seeing a properly functioning switch should check wiring and valve. Noticing an open circuit, take the steps to fix it. 
  • After that, reconnect the feed wire and put a paper clip at the end of the opposite port end in case of seeing the test light turning on. Otherwise, you have to ground the valve case to frame rail and repeat the paper clip test mentioned here.
  • In case the test in the previous step has made paper, clip adheres, do like the tip above states. But do it in an opposite manner (front for ‘F’ models and rear for ‘E’ models). 
  • Then, tweak off the fuel hose, take away the fuel hose from the carb, place it in a container, and crank the engine. 
  • Finally, you should install a new valve solenoid if the fuel flows constantly. Otherwise, install a new valve assembly for smooth operation. 

Pro Tip: Once you have found that the valve is faulty, you can remove it, clean it properly, and put it back. Lots of users solved their problems this way. But it can also be in a state of no return. In that case, install a new one. 

Is Replacing A Bad Fuel Tank Selector Valve Expensive?

I have seen different users spending various amounts while replacing a faulty selector valve. 

From $30 to more than $100, your expense can vary based on the labor cost, and parts’ price. 

If you can do it yourself, you will be able to save a lot. 

How Often Should You Service the Fuel Tank Selector Valve?

There is no such time period that tells you to inspect or service the valve. 

One only takes care of it when something bad happens. What I mean is that look for the signs and symptoms I have discussed above and act accordingly. 

If you don’t have previous repairing experience, you should take the vehicle to the nearest shop for proper servicing. 

With a DIY mindset, you can search and find lots of videos on replacing fuel tank separator valves. 

Final Thoughts

Knowing the symptoms of a bad fuel tank selector valve, and solving the problem can eliminate bad throttle response, rough idling, and stalling problems. 

So, noticing any situations discussed above, you should act immediately.

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