91 won't start in cold weather? - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Wrangler Forums > YJ Wrangler Technical Forum > 91 won't start in cold weather?

FS: 2007-2013 Jeep Wrangler "HALO" Angel Eye KitFlowmaster's Force II Axle-back exhaust system for the 201FS: Wranger BRIGHT License Plate LED! Just $3! Great value

Reply
Unread 01-06-2008, 10:34 AM   #1
medtech
Registered User
2005 LJ Wrangler 
 
Join Date: Jul 2006
Location: Mass
Posts: 54
91 won't start in cold weather?

I have a 91 yj. 4.0L. Engine is basically stock. When it's warm out, say above 50, the jeep starts fine. When it's cold it won't start. The engine will crank but there is no spark and no fuel.

Could it be the ecu? I would try a new one but they're rather expensive and I still don't know if this would fix the problem.

Sometimes when it's around 50 the check engine light will flicker very rapidly and I can hear a relay clicking. After a minute the light will come on solid and then the jeep will fire right up. Is there some other sensor that might be temperature sensitive that would cause the ecu to shut down the engine and not allow it to start?

Thanks for any help!

medtech is offline   Reply With Quote
Unread 01-06-2008, 11:03 AM   #2
Jeeples
Registered User
2000 WJ 
 
Join Date: Jul 2006
Location: forum/f310/, UT
Posts: 4,292
It's possible that it may be the ECU, however a less expensive part to replace would be your Crankshaft Position Sensor. I would suspect this is to be problem since you are not getting any spark or fuel.
__________________
His: '00 WJ 4.7 Limited- stock

Hers: '03 WJ 4.7 V8- IRO 3", 245/75/16 Duratracs
Jeeples is offline   Reply With Quote
Unread 01-06-2008, 03:30 PM   #3
medtech
Registered User
2005 LJ Wrangler 
 
Join Date: Jul 2006
Location: Mass
Posts: 54
I've tried a new crank sensor and made sure all relays work correctly. I'll have to try a new ecu. It looks like a pain in the butt to get out, I'll have to remove the washer fluid botle too!
medtech is offline   Reply With Quote
Unread 01-06-2008, 04:24 PM   #4
sentinal02
H2 Recovery Team Member
 
sentinal02's Avatar
1992 YJ Wrangler 
 
Join Date: Feb 2003
Location: New York
Posts: 6,688
Quote:
Originally Posted by medtech
I've tried a new crank sensor and made sure all relays work correctly. I'll have to try a new ecu. It looks like a pain in the butt to get out, I'll have to remove the washer fluid botle too!
next time try a search and read the FAQ first. I know it's long but it's got what you need in this case:

http://www.jeepforum.com/forum/f12/91-hard-no-start-long-cranks-cold-explained-490788/
__________________
RIP: '88 YJ 2.5L Ax-5 NP231
Posi-Loked. Herculined. Optima yellow top. 1" Shackle, 2" BDS. Cragar 397's Aussie front.

92 YJ 4.0L Ax-15 231
5" springs, 1" shackle 31's or 35's depending on my mood
sentinal02 is offline   Reply With Quote
Unread 01-06-2008, 07:28 PM   #5
medtech
Registered User
2005 LJ Wrangler 
 
Join Date: Jul 2006
Location: Mass
Posts: 54
Excellent. Sorry for wasting your energy making you type the link!
medtech is offline   Reply With Quote
Reply
Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.