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Replacing Your Fuel Injectors
 
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Pelican Technical Article:

Replacing Your Fuel Injectors

Steve Vernon

Time:

3 hours3 hrs

Tab:

$5 to $600

Talent:

***

Tools:

T30 Torx, E10 Torx, 17mm wrench, small flathead screwdriver

Applicable Models:

C350 (2007-14)
SLK350 (2004-14)
CLS350 (2004-14)
CLK350 (2005-14)
E350 (2005-14)
S350 (2005-14)
SL350 (2005-14)
R350 (2006-14)
ML350 (2006-14)
Viano (2005-14)
Sprinter (2006-14)
CLC350 (2008-14)
GLK350 (2008-12)

Parts Required:

Injectors, white lithium grease, O-rings

Hot Tip:

Check for flooded cylinders

Performance Gain:

Better-running engine, improved fuel mileage

Complementary Modification:

Replace worn out hoses

If your car is starting to run rough, getting horrible gas mileage or have an error code, there is a good chance it is time to replace the fuel injectors. A properly working injector will send a precise amount of atomized fuel into the induction system at a designated time. A weak or improperly working injector can do everything from send no fuel, to leak raw, non-atomized fuel into your engine.

If you are going to be replacing your injectors, the first step is to prep the car. I like to tell people to pull the fuel pump relay and then try to start the car. The car will turn over and then die. Do this about two to three times. It will help drain excess fuel out of your system. Also open the gas cap to help depressurize the system. Then, make sure that the car has cooled down; you don't want to be working with gasoline when the car is hot.

Have a fire extinguisher handy. There will be some spillage of fuel, as it's nearly impossible to prevent. Also, wear chemical resistant gloves if you don't want to get any gasoline on your hands, and make sure that you have plenty of paper towels or rags to help you clean up. Perform the injector removal in a clear, open, and well-ventilated space. It may not hurt to have an assistant around in case there are any problems.

You are going to be pulling the injectors out from the manifold. Make sure to clean around the area and blow it out with compressed air so you do not get dirt down into the injector openings.

You will need to remove the front (red arrow) and rear (yellow arrow) engine covers along with the air ducts (green arrows).
Figure 1

You will need to remove the front (red arrow) and rear (yellow arrow) engine covers along with the air ducts (green arrows). Please see our article on engine cover removal for additional assistance.

The fuel rail and injectors are located on both the left and right side of the intake manifold and partially hidden by the wiring loom and EGR hoses (red arrows).
Figure 2

The fuel rail and injectors are located on both the left and right side of the intake manifold and partially hidden by the wiring loom and EGR hoses (red arrows). The fuel rail is a single piece and connected by a piece of pipe that runs along the rear of the ECU unit.

To remove the rail and injector begin by disconnecting the two wiring connections on the left side of the motor (red arrows) and slipping the harness of the fuel rail (yellow arrow).
Figure 3

To remove the rail and injector begin by disconnecting the two wiring connections on the left side of the motor (red arrows) and slipping the harness of the fuel rail (yellow arrow).

Pull back on the wiring bracket on the right side only for the connection to the ECU (red arrow).
Figure 4

Pull back on the wiring bracket on the right side only for the connection to the ECU (red arrow). This will separate the wiring connection.

Tilt the EU back out of the way with the left side wiring connection still attached (red arrow).
Figure 5

Tilt the EU back out of the way with the left side wiring connection still attached (red arrow). Use a T30 Torx and remove the ECU mount on the right side of the intake manifold (yellow arrows).

Use an E10 Torx and remove the fasteners holding the wiring loom in place (red arrows) on the right side valve cover.
Figure 6

Use an E10 Torx and remove the fasteners holding the wiring loom in place (red arrows) on the right side valve cover. Use a T30 Torx and remove the single Torx screw connecting the wiring loom harness to the intake manifold (yellow arrow).

Disconnect the wiring from the coils by using a small screwdriver and pushing the clip back and then gently squeezing the clip and sliding the connections off (red arrow).
Figure 7

Disconnect the wiring from the coils by using a small screwdriver and pushing the clip back and then gently squeezing the clip and sliding the connections off (red arrow).

Use an E10 Torx and remove the bolt holding the ground wire in place (red arrow).
Figure 8

Use an E10 Torx and remove the bolt holding the ground wire in place (red arrow).

Continue to use the T30 Torx and remove the two screws holding the wiring harness bracket from the rear of the motor (red arrows).
Figure 9

Continue to use the T30 Torx and remove the two screws holding the wiring harness bracket from the rear of the motor (red arrows).

Disconnect the wiring from the air pump (red arrow).
Figure 10

Disconnect the wiring from the air pump (red arrow).

Remove all the electrical connections from the front of the right side cylinder head (red arrows) and move the wiring harness off to the side.
Figure 11

Remove all the electrical connections from the front of the right side cylinder head (red arrows) and move the wiring harness off to the side.

Use an E10 Torx and remove the wiring harness connectors from the left side bank (red arrows), including the one on the lift eye on the rear.
Figure 12

Use an E10 Torx and remove the wiring harness connectors from the left side bank (red arrows), including the one on the lift eye on the rear.

Next, remove the two T30 Torx screws (red arrows) holding the left side ECU bracket and release the EGR hose from underneath it (yellow arrow).
Figure 13

Next, remove the two T30 Torx screws (red arrows) holding the left side ECU bracket and release the EGR hose from underneath it (yellow arrow).

Pull the EGR hose from the top of the throttle body (red arrow) and move the hose out of the way.
Figure 14

Pull the EGR hose from the top of the throttle body (red arrow) and move the hose out of the way.

The connections for the injectors are small, can be brittle and in a tight spot.
Figure 15

The connections for the injectors are small, can be brittle and in a tight spot. Use a small flathead screwdriver and pop up the gray clips (red arrow). Then gently squeeze the clips and pull the connections off each injector.

Even though the engine should have been sitting overnight and you have removed the fuel pump relay to try and get the fuel out of the rail there will still be some.
Figure 16

Even though the engine should have been sitting overnight and you have removed the fuel pump relay to try and get the fuel out of the rail there will still be some. Unscrew the Schrader valve cap and wrap a screwdriver in a rag and press in the end of the Schrader valve (red arrow). This will release the remaining pressure in the system. Gasoline will come out, so be prepared to catch and dispose of it according to the regulations in your area.

Use a 17mm wrench and separate the fuel line from the distribution rail (red arrow).
Figure 17

Use a 17mm wrench and separate the fuel line from the distribution rail (red arrow). Some fuel will come out, so be prepared to catch and dispose of it according to the regulations in your area.

Remove the four E10 Torx bolts holding the fuel rail to the intake manifold (red arrows).
Figure 18

Remove the four E10 Torx bolts holding the fuel rail to the intake manifold (red arrows).

You can now pull the fuel distribution rail out from the manifold.
Figure 19

You can now pull the fuel distribution rail out from the manifold. The rail is just held in place by the six O-rings between the injectors and manifold, so you should just be able to wiggle and pull it straight up.

Once the injectors are removed there is an open hole into the intake manifold and then the combustion chamber.
Figure 20

Once the injectors are removed there is an open hole into the intake manifold and then the combustion chamber. Make sure you stick some rags or clean cloth into the opening to prevent anything from falling in (red arrows).

Take the fuel rail and injectors to your workbench.
Figure 21

Take the fuel rail and injectors to your workbench. Fuel will still be in the rail, so be prepared for some to spill out while you work on the injectors.

Each injector is held in the rail by a metal clip.
Figure 22

Each injector is held in the rail by a metal clip. Use a small flathead screwdriver and pry the clip back off the injector and rail (red arrow).

You can now wiggle and pull the injector from the rail.
Figure 23

You can now wiggle and pull the injector from the rail. Do not pull so hard that you damage or bend the rail.

New injectors will come with new O-rings.
Figure 24

New injectors will come with new O-rings. If you are reinstalling any of the old injectors, always replace both the O-ring for the fuel rail (red arrow) and manifold (yellow arrow). Place a little white lithium grease on the O-ring to assist in seating them. Installation is the reverse of removal.


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Comments and Suggestions:
WesD. Comments: Can you tell me which one is the fuel pump relay?
The fuse graph does not indicate which is the relay.
Thank you
November 24, 2016
  Followup from the Pelican Staff: On what vehicle model and year? I may have the info. - Nick at Pelican Parts  

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