Gasoline is one of the most common fuels in America today. Not only do we power our vehicles with it, but a wide variety of other tools, like chainsaws and lawn mowers are gasoline powered. Gas is also a great fire accelerant, if you have trouble starting a fire. For that matter, you can use it in Coleman lanterns and stoves. You can be sure that in a post-disaster world, gasoline will be a valuable commodity; even if cars aren’t running.
But that’s not the only situation where you might need gasoline. There are plenty of others. Getting stranded in the middle of nowhere is much easier to happen than most of us would like to admit. So is running out of gasoline while bugging out and sitting in traffic. There are actually a lot of survival situations where we might need to find a way to get our hands on gasoline quickly… even if not quite legally.
The solution, in most of these cases, is to siphon gas out of someone else’s car. Granted, that’s their gas, which they paid for; but the ethics of the situation could get a bit fuzzy in a survival situation. Dying, just because you won’t steal a few gallons of gas doesn’t make much sense, especially if the owners of the vehicle with the gas in it have abandoned it.
Siphoning Gas the Old Way
Siphoning gas used to be fairly simple, back when cars were simpler. One merely put one end of a hose into the gas tank and sucked on the other end. Eventually gas would come up the hose and you’d get a mouthful of it. That was your signal to get the hose out of your mouth and stick it into the gas can, before the gas could stop flowing.
Of course, that’s a rather dangerous way to siphon gas, as you have to inhale it into your lungs, as well as take the chance on swallowing some. I can’t recommend that method, even though I have used it more than once myself.
There’s an alternative to this method, which I’ve seen a few people use, if they have a long enough hose. The idea is to feed as much of the hose into the tank as you can, then cap the hose with your thumb, while you remove it.
If all goes well, there will be enough gas in the tank that the hose will be most of the way filled with water. Then, when you put the end into the gas can, the weight of the water in the part of the hose that is outside the vehicle will help to siphon it out.
This method doesn’t always work and in fact may not work at all on newer vehicles. Many of them have a check valve built into the filler neck, making it impossible to siphon out gas in the normal way. If that’s the case, you will have to get the gas from somewhere other than the filler.
A Safer Siphon
Before we get to ways of siphoning gas on vehicles which have that check valve, I’d like to mention a safer way of siphoning gas out of a vehicle where you can stick a hose down the filler nozzle. This method requires two hoses, the main one and a short hose, which needs to be thinner so that it can be inserted into the neck, past the unleaded gas guard, along with the regular hose.
In this method, the main hose is put into the filler neck, much like for sucking the gas out of the tank. Once it is in, the second hose is inserted into the neck, just far enough to make sure that it won’t fall out.
Then stuff a plastic grocery sack into the opening, making a seal (many people recommend a rag for this, but air will pass through a rag; it won’t pass through the plastic).
Put the end of the main hose into a gas can and blow into the smaller hose. The air pressure you provide by blowing should force gas up the other hose and out. Once it reaches the gas can, you can stop blowing.
With any of these siphon methods, if gas doesn’t come out of the vehicle’s tank, it means that the end of the hose isn’t in the gas. That can mean that the end of the hose has curled up, so that it is above the level of the gas. It can also mean that the gas tank is almost empty.
Let the Vehicle Pump it Out
If siphoning gasoline out of a vehicle by the usual means isn’t going to work, what will? Ideally, it would be to get the vehicle to pump the gasoline out by itself. But when you put the key in the ignition, the pump only stays on for three seconds. That’s not going to pump very much gasoline out.
Nevertheless, using the vehicle’s fuel pump is the best way to get the gasoline out of the tank and into a gas can. All we need is a way to trick the pump to stay on, and someplace where we can divert the gas that is pumping out of the vehicle and into our gas can. Fortunately, we can find both in most cars.
Diverting the Gas
The first thing we want to do is divert the gas that’s going to be pumped out of the tank. To do this requires knowing where that gas is going. Modern cars don’t have carburetors, but rather use what is known as “fuel injection.” This means that there is a small valve, with a nozzle, that squirts gasoline into each cylinder, at the right time in the engine’s cycle. That gas is fed to the fuel injectors through a tube known as the “fuel rail.”
This is where we are going to access the gasoline, so the first thing we need to do is locate the fuel rail. It will be on the top of the engine, running along the top of the cylinders. If the car has a 4 cylinder engine, there will only be one fuel rail. But if it has a 6 or 8 cylinder engine, it will have two fuel rails, one along the top of each row of cylinders. The fuel rail will connect directly to the tops of the injectors, which will, in turn, attach to the tops of the cylinders.
Picture of a fuel rail – taken on a 2005 VW Jetta
A cap can be found at the end of the fuel rail, which is usually threaded. Under that cap is a Schrader valve; the same kind of valve that is used on the inside of tire valve stems. It can be removed with a Schrader valve wrench. There are several styles of these, but the most common is shown in the picture below.
With the valve removed, attach a piece of hose to the end of the fuel rail, right over the threads for the cap.
If your hose doesn’t fit tightly, use a hose clamp to make it snug. Place the other end of the hose into a gas can.
Tricking the Car
Now that we’re ready to collect the gas, we need to trick the fuel pump in the car into turning on and staying on longer than three seconds. To do this, we need to remove the fuel pump relay and jumper across it.
The fuel pump relay is probably located in the engine compartment, in a plastic box, together with other relays and possibly even some fuses. If there is no such box inside the engine compartment of the car you are trying to siphon the fuel out of, then it is probably located under the dashboard, again, with other relays and fuses. If you can’t find it, look for information in the vehicle’s owner’s manual.
Relays can be thought of as remote control switches. There is a small electromagnet inside there, which controls a switch. When the electromagnet is activated, it closes the switch, allowing current to flow through the relay. They are used in cases where more current needs to flow through to the item that is going to use that electrical current, than the controller can provide. In this case, turning on the fuel pump is a function of the car’s computer, which can’t pass enough current to operate the pump, so a relay is used.
Relays can vary in quantity and appearance; but these square relays are rather common. What we’re going to want to do is jumper across the relay. So we need to know which contacts to jumper across. In the case of this particular relay, that’s contacts 3 and 5. We know this, because of the little diagram molded into the side of the relay’s case in the diagram below.
Notice on the diagram that contacts 1 & 2 are connected together through a box. This is the coil or electromagnet. Contacts 3 & 5 are also connected together; but this time through a symbol that looks like two lines that don’t quite meet, because the one coming from 3 is crooked. This is the electrical symbol for a switch. We want to concern ourselves with the switch part of the relay, not the coil part, as it is the switch which would normally get the electricity to the fuel pump. So, regardless of how your relay looks, you want to find which parts make up the switch and work with them.
Relay diagram – contacts 1 & 2 are the coil and contacts 3 & 5 are the switch
If we look at the bottom of the relay, we can see that the different tabs are marked as well, with the same numbers that are on the diagram. With three tabs running in one direction and the fourth tab running perpendicular to them, the relay can only be installed in its socket one way. Therefore, even if the socket is not numbered, we know which contact in the socket is which number.
Bottom of relay, showing contact numbers
With the relay removed from its socket, we can jumper across contacts 3 and 5 with any piece of wire, pushing the ends of the wire down into the slots in the socket, just as the tabs on the relay itself would push down into it. It is best to use a solid wire for this, rather than a stranded one, but if all you have is stranded wire, it will work. Strip back enough of the insulation to ensure good electrical contact.
Now that the jumper is installed, all we have to do is to turn on the ignition key and the pump will start running, pumping gasoline out of the tank, through the fuel rail and into our gas can. If the gas doesn’t start flowing after a few seconds, turn off the key and verify that the jumper wire is firmly into the socket.
What If We Don’t Have the Key?
If you don’t have the key to the vehicle, but can still get into it, the same thing can be done by using a wire to jumper power from the positive terminal of a car battery to one of the two switch contacts from the relay (either 3 or 5 for this relay). I can’t tell you which, because it will depend on the make and model of the car. You will probably need to try one and the other to find which one works. Don’t worry about damaging the car, you won’t.
To do this, using a battery from another vehicle, you’ll also need to use jumper cables to attach the negative pole of the other vehicle’s battery to the negative pole of the vehicle’s battery you are trying to get the gas from. If there is no battery or battery cable, find a good solid piece of metal on the engine and attach the jumper cable there.
Remember, what you’re trying to do is to fake what the car’s control system does, supplying electricity to the fuel pump, so that it will work. To do this, you have to have a complete circuit. That’s why you have to have jumper cables.
When You Can’t Get to the Engine
The above method is fine and dandy, assuming that you have the keys to the vehicle so that you can get into it and turn on the ignition. It also helps if the vehicle you’re getting the gas out of is still functional. But what about a worst-case scenario, such as an EMP; is there still a way to get the gas out?
The simple answer is “yes.” There are actually two ways; but that doesn’t mean that they will be simple to do.
Using the Fuel Pump
For the first way, we’re going to fool the fuel pump once again, but not use the relay or the fuel rail in the engine compartment. While you could break the window and get into the car to pop the hood, maybe there’s some reason why you don’t want to do that. In that case, we need to do everything from underneath the car.
There are two things you’ll need to access under the car for this: the fuel filter and the wires leading to the fuel pump. The filter will be located mounted to the side of the vehicle’s frame and the wires will be the only wires going to the top of the fuel tank. You won’t be able to see where they connect, but you will be able to see them going up there.
Remove the fuel filter by removing the hose clamps that hold it to the fuel lines. You may also need to remove a screw that holds the clamp in place, depending on the style of filter. With the filter removed, you can attach a hose to the line coming from the back of the vehicle, which is the feed line from the fuel pump. Use a hose clamp to make sure it is a tight connection, if necessary.
Find the wires providing power to the fuel pump and cut them, attaching your own. Most likely there will be two wires, as the fuel tank is isolated from the vehicle and the pump will need both a positive and negative wire. Connect your own wires and attach the other end to the vehicle’s battery to get the pump started.
Wires in vehicles are color coded, so there’s no way of saying what colors they are. If one of the wires is black, chances are it is the ground or negative wire. If not, take a guess and try. If it doesn’t work, reverse the wires. You will not have damaged the pump.
Removing the Tank
The other option is to just remove the fuel tank from the vehicle. Typically, fuel tanks are installed with two straps.
All you have to do is remove those straps and lower the tank to the ground. You’ll want to put a floor jack under the tank for this, so that it doesn’t fall.
In addition to removing the hardware at the ends of the fuel tank straps, you’ll need to disconnect the filler neck and probably the fuel lines leaving the tank to go to the engine.
With the tank removed from the vehicle, you can easily scavenge the fuel from it.
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