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Unread 07-22-2011, 02:42 PM   #1
mccraneyj
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How to tell which fuel injector is bad?

Hey guys got another one for ya! My 02 six cyl wrangler is running very rich got my cat changed and muffler they are filled with soot. I got all the signs of a bad fuel injector my question is how do you know which one is bad

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Unread 07-22-2011, 02:57 PM   #2
herbiehind
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any codes? you'd have misfire codes . also what's your current mileage ? how are your plugs? unplug each injector one at a time and see if it changes . bet it will . many things can cause rich , like 02 sensors . how many miles ?
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Unread 07-22-2011, 03:09 PM   #3
Varnish
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I was just troubleshooting some injectors last night and what I did was buy a cheapo 6 pack of those little clear plastic water bottles. I emptied em, pulled the fuel rail, surrounded each injector with a bottle. I had to twist some of the injectors to get the plugs to reach the harness with the rail pulled out. I unplugged the coil pack and then had somebody turn the engine over and watched for the pattern. Worked great. You could tell both from seeing the spray and also from the quantity of fuel in each bottle. Wear safety glasses, no spark/fire nearby, and keep an extinguisher handy. If you have a leaky injector you may not even need to turn over the motor, just pressurize the rail by putting the key in the run position a few times and see if any are dripping.
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Unread 07-22-2011, 03:11 PM   #4
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Even easier actually is you could pull the plugs and look for a black one.
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Unread 07-22-2011, 06:08 PM   #5
Jerry Bransford
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I use a $5 mechanic's stethoscope to listen to each injector. A bad injector will often sound different from the others.
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Unread 07-22-2011, 06:20 PM   #6
kloppk
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Quote:
Originally Posted by Jerry Bransford View Post
I use a $5 mechanic's stethoscope to listen to each injector. A bad injector will often sound different from the others.
X2

I just use a large screwdriver as a stethoscope. Just put the handle against your ear and then touch the blade of the screwdriver on each injector. You'll hear the injectors clicking. Just listen to each one at a time. A bad one will sound different from the rest.
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Unread 07-22-2011, 06:42 PM   #7
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If it's running rich there could be a injector leaking fuel,Test by pulling the fuel rail with injectors attached turn key on with engine off & look at each injector to see if 1 is dripping fuel.
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Unread 07-29-2011, 08:26 PM   #8
mccraneyj
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Hey guys thanks for all the replys my jeep has just hit 100k but it has been doing this for the past 20k or so. Hopefully some time this weekend im gonna try all of your suggestions and see what i come up with. Oh and also I do have a cel light on its the large leak detection code but i have changed all the vac lines and solenoids but light still comes on but i heard this wouldnt cause my jeep to run rich? My jeep also has very poor acceleration.
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Unread 11-18-2011, 08:30 AM   #9
mccraneyj
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Checked all injecters they all seem fine i pulled them all out and turned the motor over and none are leaking so i put them back in and bought mechanic's stethoscope that the Man Jerry suggested it wouldnt hurt to have one anyway. All the injectors sounded fine so now im gonna look into the o2 sensors.
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Unread 11-18-2011, 08:47 AM   #10
chris142
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A bad MAP sensor can make it run rich too.
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Unread 11-12-2012, 02:12 PM   #11
delgajac000
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I am not sure if this was posted already but to test a fuel injector take a ohm meter and put one lead on one of the leads in the inside but close to one side. then put the other lead on the other prong on the opposite side. check link for a you tube video on how to tell.
make sure you DO NOT put the meter to volts or anything else!!!
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Unread 11-13-2012, 05:02 PM   #12
chevy2169
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Quote:
Originally Posted by Jerry Bransford View Post
I use a $5 mechanic's stethoscope to listen to each injector. A bad injector will often sound different from the others.
Quote:
Originally Posted by kloppk View Post
X2

I just use a large screwdriver as a stethoscope. Just put the handle against your ear and then touch the blade of the screwdriver on each injector. You'll hear the injectors clicking. Just listen to each one at a time. A bad one will sound different from the rest.
This and this x3.
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