KJamesJR

Jeep threw two codes at me this morning starting it up. One was a CPS, which is fine because I bought the replacment part about 2 months ago. Never put it in until now.

The other was a small evap leak. For me this is more difficult because I don't have a smoke tester. Any other way to figure out where this leak is? Are there any common problem areas to be aware of on the 98 XJ? Or anywhere I could start looking?

Thanks.

FG Jeep

chrysler products in general are known for having the rubber coupler hoses get cracks in them and setting minor leak faults. They never show up on the smoke machine. Grand Carvan's are probably the worse one out there. But look at the rubber connector at the purge valve, the feed line to the purge valve, and the canister underneath and by the fuel tank. On xj's specifically i have seen one of the canister ones get cracked up pretty good.

If all your lines look good check your gas cap seal after driving for a while and see if the seal is wet at all. if is that is a tell tale sign your gas cap is allowing vapor to leak by.

KJamesJR

+1

Will do as soon as I get some daylight.

Are these hoses listed in the Haynes Manual? I did see a chart for the evaporator system, or something similar for the I6. Would these be the hoses to check?

FG Jeep

No the evaporator is for the air conditioning. It is in the heater box in the dash. The evap lines are plastic 5/16 inch lines with rubber hose couplers on them. There are also some larger maybe 3/8 inch off the canister. The canister is a small black box on the drivers side under the near the rear wheel. It is very close to the fuel tank and has a little metal skid plate in it. The purge valve is mounted on the firewall/cowl above the blower motor behind the ac accumulator. You have a 98 like me so we do not have a LDP pump. You will be able to tell if the rubber sections are bad just looking at them. They will have splits in them. They will almost look like they were sliced with a razor blade.

KJamesJR

Awesome I'm about to start looking so wish me luck. I also may be attempting my CPS today if I have the time. Jeep is still runnin and I gotta be at work in 2 hours!

KJamesJR

Bad news... And bad news.

I couldn't find any visible issues with any of the evap lines, or the couplers. The purge valve looks questionable, as well as the gas cap. There is a very bad looking metal line running from the canister to the fuel tank. Looks like some kind of return line. really rusted. Not sure if this is creating the issue or not.

CPS... I can reach the bottom bolt easily. The top one is in a rough spot. Also... I'm beginning to realize just about every bolt on my Jeep is going to be seized up. For the CPS, it's an issue of leverage. I can't get any. Using about 14" of extension with a U-joint. Maybe I need to use a 1/2" ratchet/drive. There's also some kind of transmission line or pull in the way. Couldn't remove that either. Would free up some space. My time today is limited. Tomorrow I start again.

FG Jeep

You need to see if the purge valve is actually functioning. It more than likely is if it is setting leakage faults. It is possible that steel line is causing it. Is it soft or crumbling it when you squeeze it. It is a very easy line to replace if you decide to replace it. If the gas cap is questionable. Replace it. They live a hard life being used frequently. Make sure you get one from the dealer. The aftermarket ones tend to leak and set faults.

As for your crank sensor issues. I use a long extension 3/8 drive stuff so I can get some leverage.

KJamesJR

Anyone ever bought a cheap cigar and blow smoke into the service port? I thought about trying that...

KJamesJR

Still no luck finding the evap leak.

This CPS is a pain in the ***... I had to stop before rounding the head off the bolt. I'll probably take it in to get done. Something I was trying to avoid. Unless anyone has other suggestions.

I found the write-up in the XJ write-up section. Didn't help any because I can't get the bolts to turn. PB it for a week maybe? Buy longer extensions? As it stands... The bolt are too shallow for my socket to get a good grip. Also it's not in a location to achieve decent leverage. They're also old, so rounding them off isn't difficult. I was using an 11mm socket, which I'm sure is the right size. I hit them with WD-40 last night. Didn't help.

Passt

I made a homemade smoke tester using stuff around the house. I grabbed a tin, a bicycle inner tube valve stem, some hose, some incense (to create the smoke), and one of those electric air pumps.


I found a how-to and modified it by using stuff I had around the house instead of going to buy materials. I threw the same code, small evap leak. It ended up being one of the 90 degree rubber elbows coming off the intake manifold.

peepjeep

My "01 xj kept giving me a very small evap leak code. I replaced the gas cap and the code hasn't come back. It may not be that simple, but it was the easiest place to start and no harm in a new gas cap.

KJamesJR

Update: So this small issue turned out to be more complicated than expected...

Yes the gas cap was faulty, in addition to a large evap leak in the fuel pump o-ring. Needless to say... The fuel tank had to come down.

Instead of playing the guessing game, I took it in to a mechanic who knows my family very well. He ran the smoke test and at first nothing. He took the gas cap off, and blew into the back of it... There was no back pressure. He put the cap on, there was no leak. Jiggled the cap a bit, smoke comes oozing out.

We were about to wrap things up when I noticed a small wisp of smoke coming from the gas tank, top side. We got curious... One thing led to another, and before we know it, we've got a floor jack under the tank and disconnecting all the lines. Good thing I only had a 1/4 tank full this day...

Got the tank down and he gets his fuel pump wrench. The seal/cap slides right off, no resistance. Takes the seal/cap off ... gravel and dirt coating the o-ring, as well as in the tank.

He spills fuel all over himself.

He curses.

I laugh.

Got everything cleaned off, and realized the o-ring was brand new... Thanks OP for this one. Got everything cleaned off, reconnected, new gas cap, another smoke (3 or 4 at this point)... No leaks what-so-ever.

He clears light and tries a diagnostic on my misfire code... Asks me if I've replaced any sensors. I say "yes, crankshaft". He wipes my ECU clean, and tells me "this should fix it, computer needs to 're-learn' your new CPS". Misfire and rough idle fixed.

3 hours into it... He only asks for an hours worth of labor, $70. Stood around staring at a hot rod for an additional 45mins, priceless.

Passt

Glad you got this figured out!

chereveco

i'm having this issue also with my 2001 XJ, already replaced gas cup, but it feels just the same as the old one, ( very loose ), Will have to go to check hoses and stuff....

BimmerJeeper

So, you got that tricky CPS removed by yourself? I hear this is harder than people make it out to be. Not only getting at the bolts, but something about dropping the bolt into the bell housing and having to crank the engine by hand in order to get the dropped bolt. Sounds like a risky job.