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By now many owners have racked up a good amount of miles. And may be dealing with similar issues that did. Experiencing a rough, shaking idle? Fuel milage gone south but no change in driving habits? Receiving check engine lights with codes for misfires even after changing your plugs and checking the coils? New injectors might just be the ticket to get the 3.7l purring again (in the funny way they do). Time to get those hands dirty!
Disclaimer:
This is the documentation of a process I performed. I am not a trained mechanic, electrical engineer, or fire safety expert. There is potential danger in anything we do. In this case a 4000lb vehicle, electrical systems, open fuel systems and other unknown circumstances can culminate to a harmfull or deadly situation. I cannot be responsible for the results of your actions or the aforementioned circumstances. I have documented any special precautians that I thought of to help keep things safe, I also did happen to have a fire extinguisher nearby.
I cannot stop you from following this document and performing the task yourself. If you choose to continue. I cannot be responsible for loss or damage to your vehicle, tools or money. If you are doubtful of your skill, please leave this to the professionals.
A) Parts, Tools, Materials:
Injectors for the 3.7l are available from many different manufacturers. I believe 22# is the generic specification. After some research I found the ford/bosch XF2E-C4B is what many jeep 4.0l (older inline 6, not the optional Nitro 4.0l v6) owners install as a replacement for the "sub par" units that came from the factory. I tried them in my 3.7l and found they did work. I would not consider them and "Upgrade" per se. Rather a potential alternative.
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Tools
Socket wrench - 3/8 preferably
Socket extension - 6" or combo of shorty ones used together
10mm socket - Ignition coil and fuel rail bolts
13mm socket - Alternator power cable nut
10mm box wrench - Negative battery terminal strap nut
Screw driver/s - Intake boot clamp removal, and other misc uses
5/16 fuel line disconnect tool (Yellow)- This $3.50 plastic one worked flawlessly after my old metal one faired poorly
MISC. - something non-marring to pull orings just incase.
Materials
Canned air - Clean injector bores before removal. Could use an air compressor
Cotton swabs - Clean injector bores
Rags - (not pictured) Catch spilled fuel, clean hands for handling new injectors
Oring lube - (not pictured) Motor oil or fuel is most suggested. Fuel evaporates quickly so I used motor oil
![]()
B) Prep
First order of business is to depressurize the fuel system...
Prop open the hood, then Open the fuse box behind the battery.
![]()
Pull the yellow 20amp fuse #25 for the fuel pump (circled on right) with the puller (circled on left).
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Put the key in the ignition and crank the engine. It will probably try to start then stumble and die immediately. Crank the engine for a few more seconds. Pull the key and keep the fuel pump fuse disconnected.
Next, Use the 10mm box wrench to loosen the nut on the negative battery terminal strap. Pull the strap off the terminal and push it aside so it won't slip back. It's best to restrain it somehow for the rest of the process. If it slips back and touches the terminal it will arc a small amount as the electronics power up. This is bad news with the fuel system open and fuel vapor present.
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C) Clearing a path to the fuel rail
Disconnect the IAT (Incoming air Temperature) sensor (circled). This requires pulling the red tab before the disconnect clip can be depressed and the plug removed. The IAT sensor on Late models will be on the right like mine. Early models will be to the left of the throttle body at the back of the intake.
![]()
Remove the intake. (Mine is a K&N) Late models: unclip the filter box cover then loosen the boot clamp at the throttle body side and remove the whole thing. Early models are similar except for the square "hat" over the throttle body. I'm unfamiliar with it's removal unfortunately.
![]()
Loosen the 3x 10mm bolts holding in the ignition coils on the drivers side. Then pull the coils (full removal not necessary)
![]()
To finish clearing the way for the fuel rail, disconnect the throttle body control plug (left); then (bottom) disconnect the alternator plug and power cable (13mm nut). Take note of the fuel supply connection (right)
![]()
Clip on the fuel line disconnect tool
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Push the tool into the fuel supply line connector.
![]()
Place a rag under the connection to catch fuel that will spill out. Then pull the fuel supply line off the fuel rail nipple. Place a rag over the line to prevent contaminates from falling in.
![]()
Now time to disconect all 6 injector electrical plugs.
![]()
Like the IAT sensor and Alternator connections; the red clip must be pulled up before the black tab (circled) can be depressed and the plug removed. I used a flathead screwdriver. It takes patience, but with careful force the red clips will yeld without breaking.
![]()
D) Fuel rail and injector removal/install
Remove the 4x 10mm bolts holding the fuel rail in place (2 per bank)
![]()
Blow out each injector bore to clear loose debris that would otherwise fall into the engine.
![]()
Pull out the injectors one bank at a time. This requires a good amount of force. The orings are likely seated snugly. Be ready for it to "let go" though.
![]()
This is where the real problem solving skill comes in. How to maneuver the ungainly fuel rail out. The most headache for me was the small gap between the AC line and dipstick tube. I figured it out eventually, but I suggest placing rags under the rail nipple to catch spillage. Based on some images I've seen, the AC lines on early model Nitros may have been routed differently. This may make fuel rail removal more difficult, or it may make it easier. I can't say for sure.
![]()
Success!
![]()
Notice some injectors came out without the orings.
![]()
Disclaimer:
This is the documentation of a process I performed. I am not a trained mechanic, electrical engineer, or fire safety expert. There is potential danger in anything we do. In this case a 4000lb vehicle, electrical systems, open fuel systems and other unknown circumstances can culminate to a harmfull or deadly situation. I cannot be responsible for the results of your actions or the aforementioned circumstances. I have documented any special precautians that I thought of to help keep things safe, I also did happen to have a fire extinguisher nearby.
I cannot stop you from following this document and performing the task yourself. If you choose to continue. I cannot be responsible for loss or damage to your vehicle, tools or money. If you are doubtful of your skill, please leave this to the professionals.
A) Parts, Tools, Materials:
Injectors for the 3.7l are available from many different manufacturers. I believe 22# is the generic specification. After some research I found the ford/bosch XF2E-C4B is what many jeep 4.0l (older inline 6, not the optional Nitro 4.0l v6) owners install as a replacement for the "sub par" units that came from the factory. I tried them in my 3.7l and found they did work. I would not consider them and "Upgrade" per se. Rather a potential alternative.
Tools
Socket wrench - 3/8 preferably
Socket extension - 6" or combo of shorty ones used together
10mm socket - Ignition coil and fuel rail bolts
13mm socket - Alternator power cable nut
10mm box wrench - Negative battery terminal strap nut
Screw driver/s - Intake boot clamp removal, and other misc uses
5/16 fuel line disconnect tool (Yellow)- This $3.50 plastic one worked flawlessly after my old metal one faired poorly
MISC. - something non-marring to pull orings just incase.
Materials
Canned air - Clean injector bores before removal. Could use an air compressor
Cotton swabs - Clean injector bores
Rags - (not pictured) Catch spilled fuel, clean hands for handling new injectors
Oring lube - (not pictured) Motor oil or fuel is most suggested. Fuel evaporates quickly so I used motor oil
B) Prep
First order of business is to depressurize the fuel system...
Prop open the hood, then Open the fuse box behind the battery.
Pull the yellow 20amp fuse #25 for the fuel pump (circled on right) with the puller (circled on left).
Put the key in the ignition and crank the engine. It will probably try to start then stumble and die immediately. Crank the engine for a few more seconds. Pull the key and keep the fuel pump fuse disconnected.
Next, Use the 10mm box wrench to loosen the nut on the negative battery terminal strap. Pull the strap off the terminal and push it aside so it won't slip back. It's best to restrain it somehow for the rest of the process. If it slips back and touches the terminal it will arc a small amount as the electronics power up. This is bad news with the fuel system open and fuel vapor present.
C) Clearing a path to the fuel rail
Disconnect the IAT (Incoming air Temperature) sensor (circled). This requires pulling the red tab before the disconnect clip can be depressed and the plug removed. The IAT sensor on Late models will be on the right like mine. Early models will be to the left of the throttle body at the back of the intake.
Remove the intake. (Mine is a K&N) Late models: unclip the filter box cover then loosen the boot clamp at the throttle body side and remove the whole thing. Early models are similar except for the square "hat" over the throttle body. I'm unfamiliar with it's removal unfortunately.
Loosen the 3x 10mm bolts holding in the ignition coils on the drivers side. Then pull the coils (full removal not necessary)
To finish clearing the way for the fuel rail, disconnect the throttle body control plug (left); then (bottom) disconnect the alternator plug and power cable (13mm nut). Take note of the fuel supply connection (right)
Clip on the fuel line disconnect tool
Push the tool into the fuel supply line connector.
Place a rag under the connection to catch fuel that will spill out. Then pull the fuel supply line off the fuel rail nipple. Place a rag over the line to prevent contaminates from falling in.
Now time to disconect all 6 injector electrical plugs.
Like the IAT sensor and Alternator connections; the red clip must be pulled up before the black tab (circled) can be depressed and the plug removed. I used a flathead screwdriver. It takes patience, but with careful force the red clips will yeld without breaking.
D) Fuel rail and injector removal/install
Remove the 4x 10mm bolts holding the fuel rail in place (2 per bank)
Blow out each injector bore to clear loose debris that would otherwise fall into the engine.
Pull out the injectors one bank at a time. This requires a good amount of force. The orings are likely seated snugly. Be ready for it to "let go" though.
This is where the real problem solving skill comes in. How to maneuver the ungainly fuel rail out. The most headache for me was the small gap between the AC line and dipstick tube. I figured it out eventually, but I suggest placing rags under the rail nipple to catch spillage. Based on some images I've seen, the AC lines on early model Nitros may have been routed differently. This may make fuel rail removal more difficult, or it may make it easier. I can't say for sure.
Success!
Notice some injectors came out without the orings.
