Replacing Cobalt Fuel Injectors: A Step-By-Step Guide

If you're experiencing problems with your Chevy Cobalt, it could be time to replace the fuel injectors. Fuel injectors regulate the amount of pressurised fuel used for each engine cycle, and there is one injector per cylinder in an engine. This function was previously performed passively by carburetors until the late 1980s. One of the advantages of fuel injectors is the programmable firmware that allows them to handle different fuels. When fuel injectors fail or clog, engine power is reduced and misfires will occur. The check engine light will turn on and, as the issue progresses, the engine may stall immediately after starting, fail to start, hesitate under throttle or vibrate roughly.

Replacing fuel injectors can be a complicated process and is not recommended as a DIY job. The risk of fire is high, and a good amount of knowledge is required to remove the injectors, intake manifold, fuel rail and other components. If done incorrectly, it can further damage the vehicle.

Disconnect the negative battery cable and relieve the fuel system pressure

Disconnecting the negative battery cable and relieving the fuel system pressure are important steps to take when working on a car's fuel injectors. This is because it helps to ensure safety and reduce the risk of fire when working with fuel. Here are some detailed instructions on how to do this in a Chevrolet Cobalt:

First, locate the negative battery cable. This is usually a black cable connected to the negative terminal of the battery, which is often marked with a "-" symbol. Use a socket wrench to loosen the nut that secures the cable to the terminal. Once it is loose, carefully remove the cable from the battery. Make sure that the cable does not touch any metal parts of the car, as this could cause a short circuit.

Next, to relieve the fuel system pressure, briefly run the engine with the fuel pump fuse removed. This will reduce the pressure within the fuel rail. It is important to make sure that the engine is cold before doing this step.

After completing these steps, you can continue with the rest of the fuel injector replacement procedure. Remember to exercise caution when working with fuel and always refer to a professional mechanic if you are unsure about any part of the process.

It is also important to note that working on fuel injectors can be a complicated process and it is recommended that fuel injector replacement be left to a professional.

Remove the coolant overflow pipe and disconnect the fuel supply pipe from the fuel rail

To remove the coolant overflow pipe and disconnect the fuel supply pipe from the fuel rail of a Chevrolet Cobalt, follow these steps:

First, wait for the engine to cool down. Next, relieve the pressure within the fuel rail by briefly running the engine with the fuel pump fuse removed. Then, remove the upper plenum on the intake manifold, along with any cables, hoses, or wiring that may restrict access to the fuel rail. Now, you can remove the supply and return lines from the fuel rail.

To disconnect the fuel supply pipe from the fuel rail, you will need to release the little plastic clip from the rubber hose that comes up from underneath, as well as the metal clip from the chrome fuel tube above. The chrome twist fitting should turn freely. You may need a special tool to disconnect the fuel line without damaging it. A fuel line disconnect tool can be purchased from auto stores. Alternatively, you can use a small flat-head screwdriver to press down on the collar of the quick-connect fitting while pulling the fuel line away from the fuel rail.

Once the fuel supply pipe is disconnected, you can proceed to removing the coolant overflow pipe. The coolant overflow pipe is located near the air intake cover. You may need to loosen and lift the plastic fuse box/ECU to access the coolant overflow pipe and its bracket. Loosen the bolts holding the fuse box/ECU in place, then wiggle the bracket and lock washer with a flat-head screwdriver.

Finally, to remove the coolant overflow pipe, you will need to release the lock on the stud holding it in place. Use a screwdriver to pop off the lock, then remove the pipe.

Remove the fuel rail and the fuel injectors from the cylinder head ports

To remove the fuel rail and the fuel injectors from the cylinder head ports, follow these steps:

Firstly, disconnect the negative battery cable with a socket wrench. Then, relieve the fuel system pressure. Remove the coolant overflow pipe and disconnect the fuel supply pipe from the fuel rail with a back-up wrench. Now, unfasten the mounting studs on the fuel rail with a socket wrench. Pull the fuel rail back and upward to remove the fuel injectors from the cylinder head ports. Rotate the fuel rail so that the injectors are positioned downward and then remove the rail.

Next, remove the wiring harnesses for the fuel injectors. Release the retainer clip for the fuel injectors and remove them. Remove and discard the fuel injector O-rings.

At this stage, the fuel rail and the fuel injectors will be successfully removed from the cylinder head ports. You can now proceed to install new fuel injectors by reversing the removal procedure.

Remove the wiring harnesses for the fuel injectors

To remove the wiring harnesses for the fuel injectors, you will need to first relieve the fuel system pressure and disconnect the negative battery cable with a socket wrench. Next, remove the coolant overflow pipe and disconnect the fuel supply pipe from the fuel rail with a back-up wrench. Now, you can unfasten the mounting studs on the fuel rail using a socket wrench. Pull the fuel rail back and upward to remove the fuel injectors from the cylinder head ports. Rotate the fuel rail so that the injectors are positioned downward, then remove the rail.

Now you can remove the wiring harnesses for the fuel injectors. Release the retainer clip for the fuel injectors and remove them. At this point, you should also remove and discard the fuel injector O-rings.

Install the new fuel injectors and lubricate the new injector O-rings

To install the new fuel injectors, reverse the removal procedure. First, lubricate the new injector O-rings with clean engine oil. Then, insert the new fuel injectors into the fuel rail, ensuring that the O-ring seal is properly seated. The O-rings should fit very tightly to prevent fuel leaks.

Next, re-install the fuel rail by bolting it back into the intake manifold. Reconnect the supply and return lines to the fuel rail, as well as the electrical connectors to each fuel injector.

Finally, tighten the fuel rail studs, the bolts on the fuel supply pipe, and the bolt for the coolant overflow pipe using a torque wrench. Torque specifications are as follows:

• Fuel rail studs: 89 in. lbs.
• Fuel supply pipe bolts: 10 ft. lbs.
• Coolant overflow pipe bolt: 71 in. lbs.

Frequently asked questions