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Old 11-29-2010, 08:21 AM   #1
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94 2.5L Super Hard to Start when Cold Outside

Hey Guys, 1994 2.5 Fuel Injected YJ here with 90,000 miles. I am looking for a reason why it struggles to start when it is cold out. I bought it in the middle of summer and when it was warm and it would fire just fine. Very little cranking to get it to fire. The colder it gets, the harder it is to fire. What it does is just crank crank crank. I always turn the key to the point where all the lights light up and wait for about 10 seconds to let the fuel pump engergize. Usually after about 3 or 4 times of turning the key off and trying again it will fire. Battery is fine. Starter is spinning fast as could be. I changed the plugs, wires, cap, rotor, fuel filter and coil. Fuel pump has great pressure. I am struggling with this problem guys, anyone have any ideas what is causing this???? It's 30 degrees now, but here in Illinois its gonna get colder and I'm afraid she isn't going to fire on me when it gets much colder outside! Thanks.

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Old 11-30-2010, 10:13 AM   #2
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check the fuel pressure regulator, sounds like you might not have pressure in the line in the AM

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Old 11-30-2010, 06:55 PM   #3
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Try the Ecu. That could be going bad . A few people including myself have had that problem on here. Remember that when its warm out points of contact are expanded, in the cold they shrink.
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Old 11-30-2010, 08:43 PM   #4
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Shavedsasquach, that was one of the first things I was considering when researching all the posts/threads here referencing cold/hard starting. However, one common thing I noticed with everyone else is that their check engine light doesn't come on when turning the key. Mine, however, comes on. Everything works like it should, except the engine starting. So I kinda thought the ecu wasn't the culprit then. Am I wrong? Should I still look further into the ECU? Also, did you replace yours or fix it like some people have in this forum?
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Old 12-01-2010, 07:29 PM   #5
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This may sound stupid but it works: if the ecu is affected by colder temps as you suspect, use a hair drier or heat gun and warm it up for a few minutes and then try to start it. I have read this works but have never had to try it...
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Old 12-01-2010, 08:04 PM   #6
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How long has this been going on? I also have a 94,mine started in Sept. when it first started my check engine light came on and eventually took time to come on. I changed my distributer cap and rotor, crankshaft positioning sensor and finally narrowed it down to the ecu.All of those will give a hard start and are cheaper to replace. It took three weeks til mine finally wouldn't start. Im not electronically handy so I changed mine out instead of soldering the connections. I paid 275 from the company Woodfin inc. I have to look the # up or check the other post I replied to.I gave that guy the #.No chain auto parts store around me had any ,they needed the ecu out of my jeep to refurbish. I tried the hair dryer trick,it didn't work for me.I don't think it was powerful enough. Good luck. Did you try the Haynes manual?
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Old 12-02-2010, 07:27 AM   #7
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Thanks guys for the replies. This has pretty much been going on since it started getting cooler here in Illinois. I bought it in July and started great then when it was warm out. I started noticing something in the amount of time it took to start on the cooler mornings. Now that it's 20-30 in the morning she is struggling bad to fire. I do notice that if I leave 'er in the garage overnight she starts a lot better. So, I think gonna pull the ecu out this weekend and see how it looks. Might try soldering it back into shape. If not, I will try to get one ordered. Thanks again for your help!
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Old 12-02-2010, 03:52 PM   #8
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Look on top of the capacitors for any corrosion. I just swapped mine out w/ new ones from Radio Shack. Took approximately 1 hour & I have very little soldering experience. There's a good link on Jeep Forums, google "Brain surgery on a 95 Wrangler". Has a great thread w/ pics.
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Old 12-04-2010, 09:56 AM   #9
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Well I replaced the 3 caps on the board last night. Let her sit outside and she is still not starting quickly. Still just cranking and cranking and eventually firing. I think I'm going to try the fuel pressure regulator next and see what happens. If that doesn't do it, I'm not sure what the next step should be. Any ideas?
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Old 03-20-2011, 08:38 AM   #10
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Well it's march now, how did things work out? What was teh end culprite? I have a 95 and am having the same problem right now. Replaced all teh usual things, gonna dig into teh ECU today, I also heard the Coil and or Pick up coil could be the problem. Any responses would be greatly appreciated.
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Old 03-21-2011, 08:22 AM   #11
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Well I think I finally found the problem but still haven't gotten around to fixing it yet. The jeep is my DD in the winter when it's crappy out and I couldn't take the chance of not having it for a couple of days. What I found was my fuel pressure at the rail is at about 80psi when running. It should only be 35ish. I changed the regulator and that didn't do anything. Basically what is going on when I first try to start the jeep the cylinders get flooded with massive amounts of fuel and has a hard time firing. What I've got is a pinched return line somewhere right around where the lines enter the tank. The skid plate looks kinda rusty so I wasn't sure how many days it would take for me to drop the tank and everything to inspect. So I should hopefully be getting to it soon since spring offically started yesterday. I will keep you posted on my findings!
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Old 03-21-2011, 12:55 PM   #12
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A block heater might be a good idea once you've addressed the key issues. Just a thought My 94 2.5L will start in -15F like it's 50F with it plugged in for a few hours or overnight.
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Old 03-21-2011, 08:20 PM   #13
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Another thing I would do once you've fixed your main problem is to possibly run thinner oil in the winter time, like a 5W instead of a 10W. I've heard that helps in colder weather, although I've never tried it myself, I never had the need to. Also, one thing I did for my old Bronco II that I used to have was to buy a bigger, higher amperage battery than it had originally. I lived in the Upper Peninsula of Michigan for a few years and never had any trouble starting it in the winter, and I think in part thanks to that battery, and that thing had a V6 that was slightly larger than your engine (2.9L). Just a thought.

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