What year did anti-siphon devices appear in cars?

Siphoning fuel from cars was easy back in the day since people only needed to shove their hoses down their fuel tanks. However, in recent years, the need to prevent hazards and gas theft prompted the addition of an anti-siphon valve in cars. But what year did anti-siphon devices appear in cars? Let’s find out!

what year did anti siphon devices appear in cars honda

When was the anti-siphon valve invented?

One of the many questions most people ask regarding the anti-siphon valve is, when was the siphon invented? This question is crucial because it helps one know the best way to siphon gas from a car since vehicles with such valves have a unique way of siphoning gas.

The anti-siphon valve was invented in 1929 by Gerald Bohn, though it didn’t appear in cars till the 1990s. The anti-siphon valve is a mechanical device built for applications above ground level to prevent gas leakage if the suction pipe breaks or your vehicle rolls over.

The valve is positioned at the gas tank filler neck, where it blocks fuel from leaving the fuel tank. This not only prevents wastage and hazards but also prevents gas theft.

Anti-siphon device mechanism

The anti-siphon device working mechanism is pretty straightforward. When there is a back pressure or a leak in the suction pipe, the anti-siphon valve cover, which was already in the open position, closes. As it closes, it blocks the suction line and holds back any pressure, invariably preventing leakage from the tank.

Anti-siphon device effectiveness

The anti-siphon valve is helpful because it acts as a control and backflow-prevention valve. When leakage occurs in the suction pipe, the valve ensures no gas leaves the fuel tank. Even when your car rolls over, creating a pressure that would usually force the fuel out of the fuel tank, the valve holds back the pressure, keeping the fuel in the tank. Thus, it prevents wastage and potential fire hazards.

Because the anti-siphon device in gas tank serves as a blockage, it deters thieves from stealing your gas since they can’t easily stick a hose into the tank. Stealing gas from such vehicles requires a lot of work, which translates to more time; this they don’t have. Who wants to get caught stealing?

It is, therefore, essential you know what cars have anti-siphon valves so you make the most of it. Generally, most cars manufactured from the 1990s should have the valve. However, a great way to know if your vehicle has one is to poke your hand into your gas tank; the valve is mounted on the filler neck.

Alternatively, monitor how fast your fuel leaves the fuel tank. If your gas is constantly leaking or getting stolen, there is a high chance your car doesn’t have one.

How do you siphon gas from older cars?

Siphoning gas from older cars is easier since most don’t have an anti-siphon valve. In fact, older ones are the best cars to siphon gas from since nothing gets in your way. You only need a screwdriver, a siphon hose, and a container. To siphon gas from old cars,

  • Park your car and wait for the engine to cool down
  • Next is to open the fuel tank cover
  • Push the flap tube aside with a screwdriver. Most cars have flap tubes that allow you to shove the hose into the tank but will jam when removing it.
  • Shove one side of the hose into the gas tank and the other side into your gas can.
  • Squeeze the siphon hose bulb; it will create the pressure to move the fuel via the hose into your can. To avoid swallowing fuel, use a squeeze bulb type of hose instead of using your mouth. Moreover, it makes the whole process easier and faster.

This method is appropriate for only cars without the anti-siphon valve. Because even some vehicles that people term old could have an anti-siphon valve, this is why it is important to specifically ask what year cars can you siphon gas from traditionally. Alternatively, check to see if your vehicle has one or not.

Anti-siphon devices in modern cars

Most modern cars come with the anti-siphon or rollover valves. Many manufacturers keyed into this to not only relieve tank pressure and prevent backflow but also prevent gas theft.

So it’s worth noting that the traditional way of removing fuel from fuel tanks in much older cars won’t suffice in recent ones. The reason is that the anti-siphon device blocks the entrance into your gas tank. So, trying to siphon gas the old way may result in damage.

I have seen car owners with the mesh-type siphon valve forcing the hose down the valve. While this works, if the mesh falls into the fuel tank, you risk blocking your fuel outlet.

How to siphon gas from a car with anti-siphon technology?

With the invention of the anti-siphon device on newer cars, it has become very tedious to remove gas from the gas tank. Thus prompting many to ask, can you siphon gas out of newer cars? Yes, you can but not just as easy as with older cars.

Most cars from the 1990s have this valve, but as stated above, you can also check if yours has. 

If you’re sure your car has one, here are two methods on how to siphon gas from a car with anti-siphon technology. Either remove the anti-siphon valve or bypass the valve to access the fuel in your gas tank. I will walk you through removing the valve in subsequent sections. However, here is how to bypass an anti-siphon device and get the fuel out of your car.

Method 1: Siphoning via the fuel lines

This method is especially useful in cars where one can only access the fuel pump by dropping the fuel tank. Or perhaps for those who don’t want to drop their gas tanks. To do this,

  • Open your bonnet and locate the fuel line
  • Remove the pressure release valve (cap) from the fuel line
  • Connect a fitting hose to the fuel rail and tighten it properly
  • Place the other end of the hose inside a container or whatever you’re transferring the fuel to
  • Locate and pull out your fuel pump relay fuse (check your owner’s manual for location)
  • Turn on the ignition
  • This will prompt the fuel pump to push the fuel from the tank into your gas can.
  • Inspect it so you don’t completely drain out all the fuel; you need fuel to keep the fuel tank lubricated and cool.

You can also look through this video, as it gives a thorough explanation of the process explained above.

Method 2: By-passing the anti-siphon valve

  • Get a thin hose (about eight inches thick). It should be strong but flexible.
  • Cut one end of the hose to get a pointed, narrow tip.
  • Connect the other end of the hose to your gas can.
  • Push the pointed tip into your gas tank slowly, twisting the hose as it goes in. You should feel it going through the valve and then into the tank.
  • While in, press the siphon hose valve to get fuel out of your fuel tank.

This video gives a better visual explanation of the process highlighted above. While this second method looks much easier, it might push the anti-siphon valve into your gas tank if not done correctly. So, if you are unsure how to bypass an anti-siphon gas tank using this method, don’t attempt it.

Method 3: Drilling hole in the fuel tank (cars with plastic tank)

  • Put a container under the gas tank
  • Drill a hole in the fuel tank; the gas will flow into the container.

As a last resort, this method is only recommended for cars with plastic rubber tanks whose owners don’t mind damaging their tanks. Aside from damaging the fuel tank, removing fuel using this method in stainless tanks may result in a fire outbreak. Metal clicking against each other when drilling can cause a spark, igniting the fuel in the fuel tank.

how to bypass anti siphon gas tank

How to remove the anti-siphon from the fuel tank?

Many people often bypass the siphon valve to siphon gas because removing the valve itself is a tedious and time-consuming process. Here, you may need to replace it afterward, except you don’t mind your gas leaking or getting stolen. 

However, if you want to try, here is how to remove the anti-siphon from the fuel tank. To do this, you need a hammer, a pry bar, and pins.

  • With your car parked, open your fuel tank
  • Place the pry bar by the valve and hit it with a hammer
  • Keep hitting and twisting with the pry bar until the valve looks a bit loose
  • To ensure the valve doesn’t fall inside the gas tank, support it with pins.

You can watch this video for better visual clarification.

Final Words

While you can siphon gas from any car, the complexity or simplicity of the process will depend on your vehicle. Older cars without an anti-siphon valve are much easier than newer cars with an anti-siphon valve.

But what year did anti-siphon devices appear in cars? The device appeared in vehicles made since the 1990s, though it had been in existence before then. Knowing this is important so you know how to siphon fuel your car without causing damage.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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