Check the batter as sprsonic suggested
What happens at times is when an alternator goes it can fry the battery with it, not always but have seen it more times than not.
Thats where I would start
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| Help me diagnose: stalls on start http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=1&t=45564 |
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| Author: | jeepskate [ Mon Aug 03, 2009 9:24 pm ] |
| Post subject: | Help me diagnose: stalls on start |
So, here's what's going on: It's a 2002 KJ 3.7 with 190,000+ miles. About a year or so, maybe less, had a problem with stalling at stoplights and had the throttle position sensor and battery replaced. Less than a month ago, the battery light came on, eventually determined to be a bad alternator. Replaced alternator, has run fine with the new one. Still have the year-old battery in there. Then Saturday I drove it 50 miles to work and it ran beautifully on the trip in. It sat in the parking garage there for 8.5 hours, after which it started up and immediately stalled. Popped the hood, no obvious issues. Belt was good, nothing oozing or smoking. Tried two more times to start it and as soon as I let the rpms drop back to idle it stalled. On the next try, finally ran without stalling. At this point it's again running beautifully, no misfires, smooth and steady. Drove it home with A/C and lights on, no dimming at stoplights. The next day it started fine at home and work, no issues. Stopped for gas near my house on the way home and it started again but reluctantly. Stopped and restarted it again when I got home (maybe 2 miles, if that) and it started strong again. This afternoon at home after sitting overnight, same situation as Saturday: Cranks over and fires up, dies as soon as I take my foot off the gas. None of the idiot lights are on. I've been too busy to investigate it yet. I basically do nothing but work, watch my 4-year-old daughter and sleep until my weekend comes (Weds/Thursday). If I can get to a parts store I'll see if they can pull any codes. Ordinarily from the symptoms, I'd be thinking TPS again or the battery is on its way out. But I'm perplexed by the fact that sometimes it runs fine. It's been a long time since the plugs were changed, and I'll check them when I can. But aside from my theories, anyone have any ideas/advice? |
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| Author: | tomsjeep [ Tue Aug 04, 2009 8:01 am ] |
| Post subject: | |
'stalls on start' sounds like a Sentry Key Sytem malfunction. The thing has an interuppter that prevents the engine from running. edit: to elaborate, my TJ did this for a while. I cleaned the key extra carefully and solved the problem. But the SKS chip can malfunction, and seems able to waffle in and out. A dealership can check your key for you to make sure it's not damaged. |
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| Author: | sprsonic [ Tue Aug 04, 2009 10:14 am ] |
| Post subject: | |
do a load test on the battery, sounds like a battery condition to me |
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| Author: | Jeepjeepster [ Tue Aug 04, 2009 5:59 pm ] |
| Post subject: | |
If the sentry key is bad then a little key will light up on the dash when it dies after starting it. If it cranks good then its not the battery. Check the terminals just to be sure. If it idles nice and smooth I wouldnt think the plugs would be old or the engine would be dirty. Check the codes just to be sure. |
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| Author: | jeepkj02 [ Tue Aug 04, 2009 7:52 pm ] |
| Post subject: | |
What gas brand you usually use. I like to run a top tier gas such as Shell. Might have carbon buildup around the valves. Try running seafoam through the vacuum into the intake and mix into the oil. Change the oil after 30 minutes of driving and change the plugs. What about the timing chains? Might that be a possible cause? |
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| Author: | tommudd [ Tue Aug 04, 2009 8:28 pm ] |
| Post subject: | |
Check the batter as sprsonic suggested What happens at times is when an alternator goes it can fry the battery with it, not always but have seen it more times than not. Thats where I would start
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| Author: | jeepskate [ Tue Aug 04, 2009 9:52 pm ] |
| Post subject: | |
Thanks for all the replies! Yeah, Tom, I was kind of surprised that the battery wasn't shot when the alternator went out. I'm gonna start there anyway, but I think it's OK still. |
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| Author: | jeepskate [ Thu Aug 06, 2009 6:14 pm ] |
| Post subject: | |
So, finally had time to deal with this. Turns out almost everybody was right. Battery was marginal, throttle body gunked up, spark plugs toast. Runs like a dream now. I'm usually really diligent about maintenance (don't get to 190K otherwise), but lately my life's been running me instead of the other way around. Back to work tomorrow. Thanks again for the suggestions. |
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