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Old 01-27-2011, 09:36 AM   #1
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'95 with cold starting issues

My '95 has been having a hard time starting when the engine is cold...It cranks but wont start...thought it might be the fuel pump so i changed that...still has that problem...it also wont start when then the temp outside is cold....any ideas????


Thanks!!

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Old 01-27-2011, 11:36 AM   #2
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Quote:
Originally Posted by JeepMedic32 View Post
My '95 has been having a hard time starting when the engine is cold...It cranks but wont start...thought it might be the fuel pump so i changed that...still has that problem...it also wont start when then the temp outside is cold....any ideas????


Thanks!!

First the most important thing to check to see if you have spark. cold temps can mess with distributor and components. But also could be the crank position sensor. If not all that then check fuel filter or fuel pressure. Is it hard to start only in cold or everytime?

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Old 01-28-2011, 10:06 AM   #3
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does the fuel pump kick on "brrrrrt" as soon as you turn the key on? Or is it dead quiet?
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Old 01-28-2011, 02:46 PM   #4
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Does your CEL come on as soon as you move the key in the switch? Any CEL codes?
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Old 01-28-2011, 03:06 PM   #5
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I had this very issue, after approximately 10-15 minutes (depending on temp), I could hear a relay under the hood clicking. Then I could start the Jeep when the CEL came on.

It ended up being the capacitors in my ECU. Don't think buying a replacement ECU will fix this, I bought a replacement and it had the same problem. I swapped out the capacitors with brand new ones and now it fires up instantly no matter how cold.

Read through this link, has great troubleshooting and a pic by pic on how to do it yourself. Took me roughly an hour to swap the capacitors, including smoke/beer breaks.

Crash Course In Brain Surgery Replacing Capacitors On ECU - JeepForum.com
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Old 01-28-2011, 03:55 PM   #6
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Quote:
Originally Posted by WhiteWillSmiff View Post
I had this very issue, after approximately 10-15 minutes (depending on temp), I could hear a relay under the hood clicking. Then I could start the Jeep when the CEL came on.

It ended up being the capacitors in my ECU. Don't think buying a replacement ECU will fix this, I bought a replacement and it had the same problem. I swapped out the capacitors with brand new ones and now it fires up instantly no matter how cold.

Read through this link, has great troubleshooting and a pic by pic on how to do it yourself. Took me roughly an hour to swap the capacitors, including smoke/beer breaks.

Crash Course In Brain Surgery Replacing Capacitors On ECU - JeepForum.com
This is why I asked if you hear a delayed click under the hood or if you hear the click immediatly when you turn the key to on. If there is a delay, its your PCM (Primary Control Module-Computer) I was able to get a sweet "plug it in and go" one from autocomputerexchange.com (2) winters ago I had the same issue. I was really annoyed with waiting upwords of twenty minutes sometimes for my fuel pump to click and the check engine light to come on before I could start it. Sooooo much better now. This year, she's firing right up instantly even at -15 F at 7:00am.
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Old 01-28-2011, 04:55 PM   #7
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this problem only happens when the jeep is sitting in the cold and hasnt been running for a while and the engine is cold...check the spark plugs and they are getting spark...checked the fuel pressure when starting cold and it was about 15psi...changed the fuel pump and still having the same problem...i kept the car in the garage the other night and went to start it and it was fine...seems to only happen when the temp outside and engine is cold...it could be 5 degrees out but if the truck has been running for maybe 15 min or more it will start fine

thanks for the input everyone!!
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Old 01-28-2011, 06:01 PM   #8
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I remember reading a long time ago about someone who's pickup wouldn't start when it got cold. Turned out the MAT sensor got stuck and wouldn't read below a certain temperature, so when it got cold the PCM wouldn't give enough gas for the engine to start. Once it warmed up it would run.

It's probably a long shot, but its pretty easy to check. Let the Jeep sit for a while so its cooled down completely, then pull the connector on both the MAT sensor and engine coolant temperature sensor. Use a multimeter to check the resistance of both sensors. Since the Jeep is cold, both should read almost the same value.
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Old 02-26-2011, 01:48 PM   #9
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I had the same problem with my 95 YJ and had the chance to have a spare ECU from a junkyard.
In my case the problem went away as soon as I swapt the ECU.

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