5.0 injector swap
02-09-2012, 11:51 AM
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Year: 1996
Model: Cherokee
Engine: 4.0
What's a 5.0? Assuming that's a typo (or even if it's not...)
The injectors are held captive between the fuel rail and the intake manifold. To remove, FIRST label the wires (there's a couple that would be easy to mix up), starting at the front of the engine is #1, to #6 at the back.
Relieve the fuel pressure in the fuel rail - there's a fitting for testing the fuel pressure, it has a cap that you can unscrew (usually with your fingers), there's like a tire valve inside. Press the stem, a bit of fuel squirts out - maybe a tablespoon or so. Catch it in a rag, you don't want it all over. Put the rag outdoors to dry out.
Remove the bolts holding the fuel rail to the manifold. (10mm wrench, socket it easiest). The O-rings are usually pretty tight, and don't want to let the injectors out. You have to pull up pretty hard on the fuel rail, I use a screwdriver to pry each individual injector out a bit at a time, you can twist them around a bit too. Work carefully, don't bend the fuel rail. More fuel will spill out of the fuel rail when the injectors come out. I usually remove the injectors and the fuel rail as an assembly, then pull them from the fuel rail one at a time. There's clips that hold them into the rail.
Take your new injectors, put NEW O-rings on (they are cheap, like 10 bucks for a set of 12. Don't cheap out here, or you'll be on the side of the road watching your jeep burn when the leaking fuel catches fire). A bit of grease on the O-rings helps a lot, else they don't want to go in. Push the fuel rail back into place, bolt it up, plug the connectors in, and you're done.
If the new injectors are close to the same size (flow rating) as the old ones, you may not need to reset the computer. If they are different, you may want to reset the computer so it goes through it's learning mode again: disconnect the negative battery terminal, turn headlights on for a minute, connect it back up and you're good to go.
May take a bit longer to start, (the air needs to get out of the fuel rail), and it may not want to idle right off, should settle down after 30 seconds or so.
For information about what injectors you want, there's lots of threads about it, do a search.
The injectors are held captive between the fuel rail and the intake manifold. To remove, FIRST label the wires (there's a couple that would be easy to mix up), starting at the front of the engine is #1, to #6 at the back.
Relieve the fuel pressure in the fuel rail - there's a fitting for testing the fuel pressure, it has a cap that you can unscrew (usually with your fingers), there's like a tire valve inside. Press the stem, a bit of fuel squirts out - maybe a tablespoon or so. Catch it in a rag, you don't want it all over. Put the rag outdoors to dry out.
Remove the bolts holding the fuel rail to the manifold. (10mm wrench, socket it easiest). The O-rings are usually pretty tight, and don't want to let the injectors out. You have to pull up pretty hard on the fuel rail, I use a screwdriver to pry each individual injector out a bit at a time, you can twist them around a bit too. Work carefully, don't bend the fuel rail. More fuel will spill out of the fuel rail when the injectors come out. I usually remove the injectors and the fuel rail as an assembly, then pull them from the fuel rail one at a time. There's clips that hold them into the rail.
Take your new injectors, put NEW O-rings on (they are cheap, like 10 bucks for a set of 12. Don't cheap out here, or you'll be on the side of the road watching your jeep burn when the leaking fuel catches fire). A bit of grease on the O-rings helps a lot, else they don't want to go in. Push the fuel rail back into place, bolt it up, plug the connectors in, and you're done.
If the new injectors are close to the same size (flow rating) as the old ones, you may not need to reset the computer. If they are different, you may want to reset the computer so it goes through it's learning mode again: disconnect the negative battery terminal, turn headlights on for a minute, connect it back up and you're good to go.
May take a bit longer to start, (the air needs to get out of the fuel rail), and it may not want to idle right off, should settle down after 30 seconds or so.
For information about what injectors you want, there's lots of threads about it, do a search.
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02-09-2012, 02:25 PM
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Originally Posted by Normajean410
What's sig? Sorry I'm pretty new to the forum.
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