What's Involved in Getting a New Fuel Pump?Replacing this car part is not an easy job. It requires quite a few tools, and you must know your way around a car pretty well. Putting the fuel pump in wrong could be catastrophic, so please don't try it unless you are really sure you know what you're doing and you're ready to take full responsibility for any possible errors. First off, you have to find the right fuel pump for your S-Class Mercedes. The fuel pump usually comes with a new gas tank. Even if you'd rather go the safe route and have a professional replace your fuel pump, you could save by ordering the fuel pump and tank yourself. When you buy brand new parts and accessories from an OEM dealer, you can be sure of getting a low price. This way, you can also make sure you get a genuine Mercedes-Benz fuel pump, which comes with a one-year warranty and is guaranteed to fit. All you have to do is make sure you supply the right part number or VIN for your S-Class Mercedes.
Where is Fuel Pump On My S-Class Located and How Do I Change It?Before you access the fuel pump, make sure you have an empty gas tank or one that's less than half full. The fuel tank is located in the back of the car under one of the seats. You will have to lift the back seats up to get to it. After lifting the outer lid on the floor of your car under the seats, you will see that it's covering the gas tank housing. You will need a tool like needle nose pliers to remove the outer lid covering the area where the fuel pump is located. Then you will need to use a socket wrench to remove the nuts holding the main cover in place. Make sure you're wearing work goggles and gloves before you lift this cover because this is where things start to get messy. You can now see the fuel pump sitting submerged in gas. Now that you're inside, the first thing you need to remove is the wire harness to the fuel pump. To remove these two wires, which are attached to the fuel pump, push the visible clamp that's connecting them in with your needle-nose pliers to release them. Then, remove the fuel line by pushing the little green tab up with a flathead screwdriver. Finally, undo the two latches on either side that are keeping the fuel pump in position. With all of these things disconnected and the lids and nuts placed in an order that you can remember, remove the pump from the gas tank. Put your new S-Class fuel pump in and reconnect the harness wires, the fuel line and close the two latches. Now you can put your lid on and bolt it down with the nuts and put the metal lid over top of that, then put the cover back in place that's attached to the floor of your car. How to tell if your fuel pump needs to be replaced:
If you notice your car is hotter than usual for the time of year and the climate where you live.
If your car has a gas leak.
If you turn the key and the car doesn't begin to run.
If while someone is turning the key you're listening by the open gas tank and you don't hear a buzz coming from the gas tank.
Check the fuse box under the hood, there is a specific fuse for the fuel pump, which your car's manual can help you locate. Look at the fuse to see if it's burnt out. If you're not sure, then compare it to other fuses. A burnt out fuse could be what's causing you fuel pump problems.
Hold a finger on the fuel pump relay, which is also near the fuel pump fuse, while someone turns the key in the ignition. If you can hear or feel a click, then this is a good sign that the relay is in working order.
You can also have a mechanic check to see if the fuel pump is producing enough pressure. It should have a pressure of 60 to 70. Find out the exact pressure by checking your car manual. If the pressure is not good, then at this point you can assume that you need a new fuel pump.
It could just be that the fuel pump is not connected properly, so have that checked before you spring for a new fuel tank.
If you're driving at around 50 mph or higher and your car starts to jerk then resumes driving normally, this could be a sign pointing towards a fuel pressure problem.
If you notice that you're spending more on gas when you're still doing the same amount of driving, then this could be a sign of fuel pump trouble.
If your car suddenly picks up speed even though you haven't given it more gas.
If the engine turns off when you attempt to increase your speed.If you experience any of the above problems, save yourself unnecessary hassle by having the fuel pump checked. Plus, a second opinion can't hurt before such a costly repair. Spending the money to have your fuel pump serviced or replaced is nowhere near as bad as having your car breakdown when you're not expecting it and probably a lot cheaper.