Hey folks,

Having a problem with my cherokee this week.

First, I've had a "small evap leak" code for a couple months, but hasn't been a problem.

Second, the other night on the highway my Tach and Speedo both dropped to 0. I pulled over and restarted and everything seemed fine.

This morning, I went to start up and it turned on for about 2-4 seconds then shut off. Sounded weak. Did this 3 or 4 times.

Then I turned the key to "run" without starting. none of the gauges spiked like normal. Checked under the hood for anything obviously out of place, cracked lines, leaks, fuses....nothing seemed wrong.

Got back in, held the gas down a little, started up and held the Tach at 2000-2500 RPM (it was working now) for 15-20s. Let it idle, which it did normally, put it in gear and got to work.

Anyone have experience with this problem? I did find a post on another forum with a wrangler of the same year with a similar problem, which suggested:

1)clean the throttle body
2)replace idle control valve
3)test air and coolant temp sensors
4)small evap leak may give similar symptoms <---which i have a code for

where would a likely place for an evap leak be?

 

Check your throttle position sensor, the wire and then the sensor itself. There's a way to check it by going through the throttle stages with an ohms meter and looking for drops, and a way to calculate the position in accordance with the t-body. I couldn't find the information on my phone, but I'm sure a nice Google search should turn something up. Also your crank sensor could be a part of it.

 

With your model year I would suspect the gas cap is defective. First, remove the cap and examine it, reinstall it securely, remove the battery negative (-) cable for a few minutes to see if the CEL clears, then drive it through several key cycles (stop/restart) and see what happens. If the cap looked defective, or the CEL pops back on with the same code replace the cap with a new MOPAR cap and then see what happens.

 

hey folks. so I'm thinking the problem is in my fuel line, possibly the pump....the problem only happens if the car has been sitting for more then 10 hours or so, and if I turn the key off and on 6-8 times without trying to crank, to let the fuel pressure build, and then it'll start up normally. gonna check the fuel line pressure when i have a chance some morning. does this make sense to people?

 

That's called the "poor man's prime". If the check valve in the fuel pump assembly is faulty it loses pressure while sitting, cycling the key to RUN a few times builds up pressure before starting.

However your original description actually sounds like a low battery. It can be low enough to start the engine but put enough of a load on the alternator that it just drags it to a stop. I would absolutely disassemble, clean, and reassemble all of the battery and ground cables you can find. Thin layers of corrosion build up on terminals, posts, and cables and they're certainly not conductive, or one of the battery's cells may be on the way out. A load test of the battery might be a good idea and any parts store should be able to do that.

Did you manage to get the evap code cleared? New gas cap?

 

Got a new battery about a month ago, cleaned the terminals when I installed it, though maybe could have done a better job (I was in the store's lot). I'll have it checked anyway, and clean the terminals again.

I have not replaced the gas cap yet but am gonna stop by NAPA on my way home from work.

 

in part to bump this thread, here are my current issues and what's been done so far:

Problems:

1st)SOMETIMES: xj will turn over, run for 3-5 seconds, then shut off. this will happen over and over again. I have been sure to turn key to "on," wait for the fuel pump to finish it's start cycle, then try and start. if it happens to shut off after a few seconds, I will turn the key on, let the fuel pump finish, turn off....repeat 8-10 times and try again. usually this gets the engine to stay on normally. i have noted that it seems these starts happen when it was relatively warm the previous day, and a cool morning.

2nd) I have received several "no bus" messages with my gauge cluster failing, always on the highway with cruise control on. the engine continues to run normally, so I just stop and restart the car, though sometimes it seems just slowing down below ~45mph is enough to get the gauges back on.

3rd) i have had a CEL for months now (no big deal, I know, but figure if i'm listing my problems i should include it). at last check it was a small evap leak, i replaced my gas cap and it went away for a few days. havent had a chance to check if its a new code yet. also may have another small leak at me leak detection pump hose, which i will be replacing soon.



based on these issues, i'm thinking one of several things:

--1 & 2 could be related? if the computer is failing somewhere, perhaps it is erroring out intermittently on both sending info to the gauges and on those few start-ups?

--1 could just be my fuel pump/check valve failing, with 2 being the corrosion build-up that has been mentioned with regards to the gauge cluster connections in the dash


based on these symptoms, anyone have some advice for me? I plan to replace the fuel pump and pull the gauges out for cleaning one of these days.