coil getting constant voltage instead of pulsating - JeepForum.com

 
LinkBack Thread Tools
post #1 of 6 Old 07-12-2010, 04:52 PM Thread Starter
headstrong50
Registered User
1993 YJ Wrangler 
 
Join Date: Dec 2009
Location: noblesville
Posts: 206
coil getting constant voltage instead of pulsating

i recently put my drive train back into my 93 yj after getting everything rebuilt. the jeep fired fine before, but when we went to turn it over, it wouldnt. i bought a new coil because i wasnt getting any spark, but that didnt help anything, so i tested the volts and instead of it pulsating at 12 volts, it was constant. what does this mean? or am i way off?


going off road is like being married, its great until you bang something you shouldnt.
headstrong50 is offline  
Sponsored Links
Advertisement
 
post #2 of 6 Old 07-12-2010, 05:16 PM
laybackman
Bikini Bridge Inspector
 
laybackman's Avatar
2010 JK Wrangler 
 
Join Date: Dec 2002
Location: Massachusetts
Posts: 6,926
Quote:
Originally Posted by headstrong50 View Post
i recently put my drive train back into my 93 yj after getting everything rebuilt. the jeep fired fine before, but when we went to turn it over, it wouldnt. i bought a new coil because i wasnt getting any spark, but that didnt help anything, so i tested the volts and instead of it pulsating at 12 volts, it was constant. what does this mean? or am i way off?
Was this a complete disassembly/rebuild of the engine?

"turn it over" does that mean the starter turns the engine but it does not fire?

Do you have fuel pressure at the fuel rail? Do you have gas? I ask becasue I have done a bunch of rebuilds and I am quite meticulous YET one time I spent an entire 12 hour day chasing a problem....yep no fuel!

If you have no fuel pressure at the fuel rail or high voltage or any spark at all coming out if the distributer you may have a problem with the ECM. Does your CEL come on when you turn the ignition switch to the ON position?
If not then you have an ECM problem.

IF the CEL does go on and you have fuel opressure at the rail but it will not fire up I would suspect the crank sensor first.

The coil input is always 12v when starting/running. It is the output voltage to the distibuter cap that is important. That voltage depends on the coil output. But if the crank sensor or the vss sensor 'sees' no movement of the turning asssembly you get no spark of fuel after a second or so of cranking.

EDIT if the sensor in the distributer sees no mevement the same thing happens I beleive.

Do you know what was good about the good old days? I wasn't good, And I wasn't old!

Senators and Congressman should wear uniforms like NASCAR drivers so we could identify their corporate sponsors....
laybackman is offline  
post #3 of 6 Old 07-12-2010, 08:19 PM
ctm
Registered User
1990 YJ Wrangler 
 
Join Date: May 2007
Location: Boston MA
Posts: 1,447
for the coil it is the ground connection that is pulsed by the ignition module on the trigger signal from the distributor
ctm is offline  
post #4 of 6 Old 07-13-2010, 12:15 AM Thread Starter
headstrong50
Registered User
1993 YJ Wrangler 
 
Join Date: Dec 2009
Location: noblesville
Posts: 206
the engine cranks, just does not run. i checked the fuel rail and i have pressure.

going off road is like being married, its great until you bang something you shouldnt.
headstrong50 is offline  
post #5 of 6 Old 07-13-2010, 01:51 AM
Douglas S.
Registered User
1991  
 
Join Date: Jun 2007
Location: Saskatchewan, Canada
Posts: 2,645
Have you checked for codes?

1991 Land Cruiser HDJ81
1987 YJ Laredo
Douglas S. is offline  
post #6 of 6 Old 07-13-2010, 03:32 AM
Mark05059
Registered User
1989 YJ Wrangler 
 
Join Date: Mar 2009
Location: quechee Vermont
Posts: 4,699
sounding like a crank sensor issue.

1998 ZJ 5.2 Auto

1989 Wrangler Black Bone Stock 2.5l 5spd
/l , [____],
|---L--[]lllllll[]-
()_) ()_)==O=)_)
Mark05059 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com 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 e-mail address for yourself.



Email Address:
OR

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.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
Pulsating Brakes turkish6 TJ Wrangler Technical Forum 8 04-01-2010 08:35 PM
No Spark but coil has voltage at supply bsousa YJ Wrangler Technical Forum 2 06-12-2008 04:51 PM
Voltage to the coil ? CUtigger YJ Wrangler Technical Forum 19 05-30-2008 07:17 AM
90YJ No Voltage at Coil ctm YJ Wrangler Technical Forum 7 02-09-2008 02:43 PM
coil voltage Scurv YJ Wrangler Technical Forum 1 03-10-2007 09:22 PM

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 On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome