Check Engine Light
Thread Starter
CF Veteran
Joined: Aug 2010
Posts: 1,085
Likes: 3
From: Fountain Inn, SC
Year: 1988
Model: Comanche (MJ)
Engine: I6 4.0L
so my check engine light has been on before and then i gotta it reset when i hooked it up to a computer where the codes said evap leak or something...at the time i didnt wanna spend 75 bucks just for them to smoke it to find the leak and then have to pay more to fix it...so i went and bought another case cap which is wiggly as heck. but yeah it fixed it for a little bit then it came back on for 2 weeks then off for a week now its back on ugh..any ideas? or know how much it would cost to fix the fuel thingy if thats whats wrong with it. thanks
Seasoned Member
Joined: Jun 2009
Posts: 337
Likes: 22
From: Earth
Year: 1998
Model: Grand Cherokee
Engine: 5.9 V8
I've had a similar problem. I reset it multiple times, occasionally it was accompanied by a misfire. Fixed it by replacing an evap tube elbow located on the right side of the intake manifold. Mine was dried out and needed to be replaced($2 from autozone). You might be able to push yours back in, that is if this is the problem. It usually blows out upon start-up.
Thread Starter
CF Veteran
Joined: Aug 2010
Posts: 1,085
Likes: 3
From: Fountain Inn, SC
Year: 1988
Model: Comanche (MJ)
Engine: I6 4.0L
I've had a similar problem. I reset it multiple times, occasionally it was accompanied by a misfire. Fixed it by replacing an evap tube elbow located on the right side of the intake manifold. Mine was dried out and needed to be replaced($2 from autozone). You might be able to push yours back in, that is if this is the problem. It usually blows out upon start-up.
Senior Member
Joined: Jan 2010
Posts: 999
Likes: 0
From: Brentwood, TN
Year: 2001
Model: Cherokee
Engine: 4.0
Check the square evap box under the jeep. Its towards the back on the driver side. There are two hoses that go there. My evap leak was comming from there. I had the smoke test done and there was a hose the was rotten. Easy to replace and you will probably see the rotten one right away. Here is a picture of what it looks like. I have an 01 also.
Thread Starter
CF Veteran
Joined: Aug 2010
Posts: 1,085
Likes: 3
From: Fountain Inn, SC
Year: 1988
Model: Comanche (MJ)
Engine: I6 4.0L
Check the square evap box under the jeep. Its towards the back on the driver side. There are two hoses that go there. My evap leak was comming from there. I had the smoke test done and there was a hose the was rotten. Easy to replace and you will probably see the rotten one right away. Here is a picture of what it looks like. I have an 01 also.

Thread Starter
CF Veteran
Joined: Aug 2010
Posts: 1,085
Likes: 3
From: Fountain Inn, SC
Year: 1988
Model: Comanche (MJ)
Engine: I6 4.0L
Check the square evap box under the jeep. Its towards the back on the driver side. There are two hoses that go there. My evap leak was comming from there. I had the smoke test done and there was a hose the was rotten. Easy to replace and you will probably see the rotten one right away. Here is a picture of what it looks like. I have an 01 also.
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Senior Member
Joined: Jan 2010
Posts: 999
Likes: 0
From: Brentwood, TN
Year: 2001
Model: Cherokee
Engine: 4.0
Those look a little rough. I would remove them (very easy, they just pop off) and inspect them in the light. Just make sure you some how mark where they go or just remove one at a time. Look for cracks or holes etc. I might even just replace both. You can see how much newer mine look compared to yourse. Check the lines going to the hoses when its light out.
Seasoned Member
Joined: Jun 2009
Posts: 337
Likes: 22
From: Earth
Year: 1998
Model: Grand Cherokee
Engine: 5.9 V8
I'll post a picture of the hoses tomorrow, when it's light out. The check engine light won't go out, it has to be reset; You can reset it by disconnecting the positive wire to your battery and touch it to the negative/ground for 5-10 minutes. That or with a code reader if you have one on hand.
Thread Starter
CF Veteran
Joined: Aug 2010
Posts: 1,085
Likes: 3
From: Fountain Inn, SC
Year: 1988
Model: Comanche (MJ)
Engine: I6 4.0L
I'll post a picture of the hoses tomorrow, when it's light out. The check engine light won't go out, it has to be reset; You can reset it by disconnecting the positive wire to your battery and touch it to the negative/ground for 5-10 minutes. That or with a code reader if you have one on hand.
Thread Starter
CF Veteran
Joined: Aug 2010
Posts: 1,085
Likes: 3
From: Fountain Inn, SC
Year: 1988
Model: Comanche (MJ)
Engine: I6 4.0L
Hey, fellas. I have a 99 XJ (only just got it less than a month ago!) which threw the same error codes recently. I replaced the gas cap already, but I checked the elbow connectors on the EVAP box and they look about as crusty and rough as 01Cherokee_Sport's. I was going to go ahead and replace them, but I was wondering if you knew the exact size of the connectors. (I know I could probably just pop them off and take them into a parts store, but figured maybe someone knew!) One is slightly larger than the other.
Going through Autozone's website I see they have "universal connectors." Is that what I want?
Here's another noob question... If I pop off the elbow connectors and attempt to measure them myself, what am I measuring? The length of the connectors up to the right angle intersection? Or the diameter of the opening?
Like I said, I'm new at this, but I'm really excited to learn and get my hands dirty, so any info would be great. Thanks!
Going through Autozone's website I see they have "universal connectors." Is that what I want?
Here's another noob question... If I pop off the elbow connectors and attempt to measure them myself, what am I measuring? The length of the connectors up to the right angle intersection? Or the diameter of the opening?
Like I said, I'm new at this, but I'm really excited to learn and get my hands dirty, so any info would be great. Thanks!
Thread Starter
CF Veteran
Joined: Aug 2010
Posts: 1,085
Likes: 3
From: Fountain Inn, SC
Year: 1988
Model: Comanche (MJ)
Engine: I6 4.0L
Hey, fellas. I have a 99 XJ (only just got it less than a month ago!) which threw the same error codes recently. I replaced the gas cap already, but I checked the elbow connectors on the EVAP box and they look about as crusty and rough as 01Cherokee_Sport's. I was going to go ahead and replace them, but I was wondering if you knew the exact size of the connectors. (I know I could probably just pop them off and take them into a parts store, but figured maybe someone knew!) One is slightly larger than the other.
Going through Autozone's website I see they have "universal connectors." Is that what I want?
Here's another noob question... If I pop off the elbow connectors and attempt to measure them myself, what am I measuring? The length of the connectors up to the right angle intersection? Or the diameter of the opening?
Like I said, I'm new at this, but I'm really excited to learn and get my hands dirty, so any info would be great. Thanks!
Going through Autozone's website I see they have "universal connectors." Is that what I want?
Here's another noob question... If I pop off the elbow connectors and attempt to measure them myself, what am I measuring? The length of the connectors up to the right angle intersection? Or the diameter of the opening?
Like I said, I'm new at this, but I'm really excited to learn and get my hands dirty, so any info would be great. Thanks!


