94 yj 4.0 that won't start... Shocking I know - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > YJ Jeep Wrangler Forum > YJ Tech Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 06-16-2014, 10:39 PM   #1
Newb
 
Join Date: Jun 2013
Posts: 6
94 yj 4.0 that won't start... Shocking I know

1994 YJ 4.0 will not start. Was running fine with no issues when I parked it but two days later it wont start. It cranks over, has plenty of spark and is getting fuel. No trouble codes except the normal 12,33,and 55. ECU is only 4 months old. New TPS and CPS when I replaced the ECU. Battery and cables are also 4 months old and hold a good charge.

1. check engine light comes on when you turn the key and the fuel pump charges.

2. turn key to run and she just cranks. checked spark, fuel and have good spark and fuel pressure.

3. Changed plugs, and wires, none were fouled but #2 had a crack in the porcelain. still no start.
4. changed distributor cap and rotor. No change
5. changed power pack, No change
6. Fuel pressure is fine and even tried a little starting fluid.

Was looking for a little advise. Everyone knows you start over thinking this stuff and miss the small things. Thanks in advance for your help.

Gopats is offline   Quote Quick Reply
Old 06-18-2014, 01:36 AM   #2
Jeeper
 
COAinPaso's Avatar
 
Join Date: Feb 2014
Location: California
Posts: 101
You changed the cap and rotor? Double check the timing.

__________________
COAinPaso

-function before style...
COAinPaso is offline   Quote Quick Reply
Old 06-18-2014, 05:30 AM   #3
Jeeper
 
Join Date: May 2014
Posts: 112
Could be a sensor that is giving a false reading that is within normal operating parameters but not where it needs to be for startup. Thereby not giving it the proper fuel spray. For example, if the Coolant Temp sensor was telling the ECU it was at 250 degrees then it would be too lean to start at if the actual temperature was 60 degrees. Get a scan tool that displays data and start looking. Does this vehicle show any attempts to start at all?
JMickey is offline   Quote Quick Reply
Old 06-18-2014, 08:05 AM   #4
Newb
 
Join Date: Jun 2013
Posts: 6
Doesn't try to start at all. Parked it on a Tuesday running fine. Hoped in it Thursday and it would only crank. Checked the basics. Getting fuel and spark. Then tried a little starting fluid. Still nothing. Fuel pressure at the rail was good all with in range. Good compression on all cylinders. First changed plugs, then wires, cap and rotor. No change. Replaced power pack/coil no change. Replaced crank position sensor, nothing... Yesterday changed coolant temp sensor no change.
Reset computer yesterday even though I had no codes except for 12 and 33. Cranked and checked again. Now throwing code 11 (no cam sensor signal/Hall effect). Today I'm going to put a new distributer in and see what happens.
Battery is 4 months old. Installed it with the new ecm. Swapped it out yesterday and didn't make any differance.
Is there any relays I can change?
Gopats is offline   Quote Quick Reply
Old 06-18-2014, 08:36 AM   #5
Jeeper
 
Join Date: May 2014
Posts: 112
If you're not getting a cam sensor signal it may not be firing the injectors. I would diagnose that first. If I'm not mistaken this engine has sequential fuel injection and needs the cam sensor for proper operation. I remember on some of the earlier GM stuff you could unplug the cam sensor and it would go into a default that would allow the engine to start which was how we quickly ruled out a cam sensor. I'm not sure if Jeep would do the same thing or not. My guess is probably not. That would be too easy.
JMickey is offline   Quote Quick Reply
Old 06-18-2014, 05:34 PM   #6
Newb
 
Join Date: Jun 2013
Posts: 6
Put a whole new distributer in today and you guessed it.... Nothing! Had it towed to a shop they are going to test the computer and a once over. Have no clue what's going on with this thing
Gopats is offline   Quote Quick Reply
Old 06-19-2014, 12:44 AM   #7
Jeeper
 
COAinPaso's Avatar
 
Join Date: Feb 2014
Location: California
Posts: 101
I had an 11 code after changing out the entire distributor. Rotor was advanced past number one. Re-installed correctly, code 11 disappeared and it runs fine now.
__________________
COAinPaso

-function before style...
COAinPaso is offline   Quote Quick Reply
Old 06-19-2014, 11:59 AM   #8
Newb
 
Join Date: Jun 2013
Posts: 6
distributor was installed by local mechanic thats been building jeeps and muscle cars for 30 years. Helped me out in the driveway and he couldn't figure it out so he took it to his shop. Free tow cant complain.
Gopats is offline   Quote Quick Reply
Old 06-26-2014, 02:27 PM   #9
Newb
 
Join Date: Jun 2013
Posts: 6
I did a valve cover gasket two days before the jeep died. After replacing the gasket I drove the jeep and it seemed fine.
Anyone have any knowledge about the two braided grounds off the engine? As for the braided grounds, I found the one off the firewall attached to the block wasn't even attached. It was just resting on the engine. The second ground off the fender that attaches near the dip stick was also not attached. it was just sitting on the fender.

Will or can this effect the computer or the starting? haven't seen much written up on these grounds and didn't have time to change them since its raining here in Boston.
Gopats is offline   Quote Quick Reply
Old 06-26-2014, 03:55 PM   #10
Jeeper
 
Join Date: May 2014
Posts: 112
They are engine electrical grounds. You really don't want to depend on your battery ground cable as being the only ground to the engine. Are they part of your starting issue? Maybe. Fix them to rule them out. Always fix the obvious stuff first.
JMickey is offline   Quote Quick Reply
Old 07-25-2014, 04:01 PM   #11
Jeeper
 
daniel8956's Avatar
 
Join Date: Feb 2013
Location: Buckley, Washington
Posts: 46
So what did it end up being? my guess would have been CPS...
daniel8956 is offline   Quote Quick Reply
Old 07-26-2014, 10:43 AM   #12
Newb
 
Join Date: Jul 2014
Posts: 8
Hello, I have a 95 4.0 that has the same exact symptoms. I was stranded with my son last week and still wont start! What did your fix end up being? Thanks
Reefrunner is offline   Quote Quick Reply
Old 07-27-2014, 10:36 AM   #13
Newb
 
Join Date: Jun 2013
Posts: 6
Sorry for the delay but the Jeep is still not running. I swapped out the PCM with another jeep and still wouldn't start but mine worked fine in the loaner jeep. Tried new relays and fuses with no change.

My electrical box under the hood had allot of corrosion, still cleaning it all up.

Did get it running once and think we tracked it down to a short in one of the wires that goes to the injectors.
Between work and my two year old I have limited time to work on it but will post updates on what i come up with.
Gopats is offline   Quote Quick Reply
Old 07-28-2014, 12:08 PM   #14
Jeeper
 
daniel8956's Avatar
 
Join Date: Feb 2013
Location: Buckley, Washington
Posts: 46
Mine was doing the same

Mine was doing the same and it ended up being the cheap autozone Crank Position Sensor Versus OEM. as minut as the differences could've been that was my issue.

Good Luck
daniel8956 is offline   Quote Quick Reply
Old 07-28-2014, 12:11 PM   #15
Jeeper
 
daniel8956's Avatar
 
Join Date: Feb 2013
Location: Buckley, Washington
Posts: 46
Same advice

Quote:
Originally Posted by Reefrunner View Post
Hello, I have a 95 4.0 that has the same exact symptoms. I was stranded with my son last week and still wont start! What did your fix end up being? Thanks
If you have checked your basics...(power, fuel, air) the first sensor I would check would be the CPS. you can type it in here and ask how to check it and it will pop up with it. mine was going out intermittently.
daniel8956 is offline   Quote Quick Reply
Old 07-28-2014, 01:51 PM   #16
Newb
 
Join Date: Jul 2014
Posts: 8
Thanks Daniel! I had replaced the cps with Napa equipment without checking the old one. Still no luck, had spark at coil, not at plug so I replaced cap and rotor, still no luck. In the process of diagnosing the MAP and TPS now...
Reefrunner is offline   Quote Quick Reply
Old 07-28-2014, 07:53 PM   #17
Jeeper
 
zachattack's Avatar
 
Join Date: Jul 2014
Location: PHX, AZ
Posts: 121
check you ignition switch as well.. i just has to redo the whole ignition system in mine.. the ignition switch would kick it over but they have 7 or so individual out puts.. the cost 16 bucks or so.. they also are common to fail..
zachattack is offline   Quote Quick Reply
Old 08-06-2014, 12:51 PM   #18
Newb
 
Join Date: Jul 2014
Posts: 8
Well I am stumped, checked timing, replaced ecm capacitors, replaced cap and rotor, replaced cps and cmp/pickup coil, other sensors seem to check out. I have fire at plugs, I have fuel at rail. Engine compression at 125psi. Tried to start engine on starting fluid..nothing. ECM not throwing any codes

zacattack-I have yet to check the ignition but would you know what the the individual outputs supply?
Reefrunner is offline   Quote Quick Reply
Old 08-06-2014, 04:44 PM   #19
Founder, ThumbJeeps

WF Supporting Member
 
sevenservices's Avatar
 
Join Date: Sep 2009
Location: Mid-Michigan/Thumb
Posts: 3,952
I thought pickup coil, usually when nothing else works its that. But, you got that... you have all three things you need.

Spark
Compresion
Fuel

And, if it ran when you parked it, its not timing. Timing doesn't just change itself all of a sudden.

Have you checked for water/moisture in the gas? Crank it for a few, pull spark plugs, look for water. Gas will spread into the metal so to speak, water will bead up.

You can also pull the fuel line, crank it over and push some fuel into a glass jar and hook the line back up. If you let it sit for a couple minutes, any water in the fuel system will turn into balls in the bottom of the jar as water is heavier than gas. If its the case, you want a can of drygas in there. Its a liquid, just named that because it eats up the water.

I'm stumped, you've done everything and you have all the things you need for it to run. Thats the only reason I think of maybe water in the gas. A little tiny droplet will cause it to foul.

Does it ever fire? will it even sputter or try at all to go on its own or is it completely no go when you crank it?
__________________
-Chris
Founder, ThumbJeeps


1994 Wrangler YJ I6 4.0 H/O Auto 3 spd. 4" RC (33x12.5) (15x8) 3:54 Gears
sevenservices is offline   Quote Quick Reply
Old 08-06-2014, 06:16 PM   #20
Jeeper
 
Join Date: May 2014
Posts: 112
You have spark. You have fuel pressure at the fuel rail. Have you checked for an injector pulse? Fuel pressure is useless unless the injectors are actually firing.
JMickey is offline   Quote Quick Reply
Old 08-14-2014, 11:24 PM   #21
Newb
 
Join Date: Jul 2014
Posts: 8
Alright guys, here to follow up. So after diagnosing the whole fuel system I found that it was getting to the cylinders. Figured I would go back to the ignition system, and even though the coil was showing spark, it wasn't sufficient enough to fire the cylinders so after a new Delphi coil from Amazon she is running better than ever. For anyone in the same boat the main symptoms were rich at idle,stumbled while driving a few times and then a run down river road east at big bend natl park on a 110 degree day, the hot coil finally took a dump. Thanks guys for the support
Reefrunner is offline   Quote Quick Reply
Old 08-14-2014, 11:42 PM   #22
Newb
 
Join Date: Jul 2014
Posts: 8
[IMG][/IMG]

Reefrunner is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Download our Mobile App

» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 09:05 PM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC