tbi probs...won't start - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Electrical
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 02-15-2008, 03:58 PM
Registered User
 
Join Date: Feb 2008
Location: Longview, tx
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
tbi probs...won't start

1988 chevy truck 454 cid w/tbi. Truck died several times. no fuel out of injectors. I removed one of the injector plugs and plugged back in, truck started and ran for a while. I was replacing the plugs and found the oxy sensor unplugged, plugged back in. Truck started and ran for a block and died and won't start. no fuel out of injectors. Checked with meter, no power to injectors. Replaced ecm. now i have power to injectors but it is constant power not pulsing, still no fuel from injectors I have fuel and spark. I checked the tps=ok. trouble codes flash 12 only, nothing else. What else could it be??? any suggestions???

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 02-15-2008, 07:00 PM
T-bucket23's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Engine basic condition - how to check Last photo:
Join Date: Aug 2005
Location: Massachusetts
Age: 56
Posts: 5,091
Wiki Edits: 26

Thanks: 7
Thanked 102 Times in 87 Posts
First off are you sure the replacement ECM is good and the Correct one. Did you replace the prom with the one from your original. If you cant answer yes to both I would hook the original ecm back up. I am fairly certain they pulse the ground on those so power there all the time MAY be normal.
Those are famous for broken or shorted wires where they go away from the flange where the air cleaner sits. You may want to take a hard look at them. I have also seen the ground in the harness a little further back rot out.
I am suspicious of the wiring near the TBI unit as you said you unplugged and re plugged and it ran for a while. I am thinking that moving the wires is what did it. I am going to look up a couple things and I will post back

Chet
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 02-15-2008, 07:17 PM
T-bucket23's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Engine basic condition - how to check Last photo:
Join Date: Aug 2005
Location: Massachusetts
Age: 56
Posts: 5,091
Wiki Edits: 26

Thanks: 7
Thanked 102 Times in 87 Posts
I was correct they pull up the ground to fire the injector. So if you check it 1 pin should be hot all the time and the other should be pulsing. If not you either havea wiring issue or a bad ECM. I would be willing to be it is wiring or a combination of both. Bad wiring can destroy the ECM drivers.
If you can locate a schematic, I would start buy checking the ground points first.

Good Luck

Chet
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 02-16-2008, 06:15 AM
Registered User
 
Join Date: Feb 2008
Location: Longview, tx
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
OK, thanks. I will keep you informed as to what happens.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 02-16-2008, 11:40 PM
snkbyt's Avatar
ASE Master
 

Last journal entry: Finished
Last photo:
Join Date: Mar 2002
Location: Salem, Oregon
Age: 61
Posts: 245
Wiki Edits: 0

Thanks: 1
Thanked 0 Times in 0 Posts
Sounds like the control module in the distributor. It sends RPM signal to PCM to control the injectors. Also it will act up intermittent. The ground for injectore comes from PCM but the pulse has to come from distributor to the PCM to Injectors.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 02-17-2008, 10:36 AM
NEW INTERIORS's Avatar
Believe in yourself !!!!!!
 

Last journal entry: 41 WILLYS FRAME
Last photo:
Join Date: Jul 2007
Location: In My Shop..
Age: 49
Posts: 10,010
Wiki Edits: 0

Thanks: 1,148
Thanked 497 Times in 369 Posts
Mine did that and it was the pick up in the distributor.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 03-12-2008, 03:28 PM
Registered User
 
Join Date: Feb 2008
Location: Longview, tx
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
no start...tbi problems.....no fuel

OK guys, I have looked for bad wiring. The TPS checks OK, The dist pickup coil checks OK, Since you can't test the dist module, I just replaced ($20.00)
I did swap the prom from the original ECM to the new one but I can't say it's good??? I can't put the old one back in as they took it for a core. Any other suggestions other than a gallon of diesel and a match.......This thing is giving me hemmoroids.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 03-12-2008, 06:02 PM
snkbyt's Avatar
ASE Master
 

Last journal entry: Finished
Last photo:
Join Date: Mar 2002
Location: Salem, Oregon
Age: 61
Posts: 245
Wiki Edits: 0

Thanks: 1
Thanked 0 Times in 0 Posts
I think we are way off base here!!! You can't read injector pulse with a voltmeter. Has to be a noid light or a lab scope. Are you checking the injectors cranking? I don't see any posts here that say 'the fuel pressure is'. Sounds like any Chev pump, starts for a freak minute then quits. No fuel out the injectors. Fuel pressure I believe is around 12# on tbi they were a low pressure system. Hope this helps.

Last edited by snkbyt; 03-12-2008 at 06:08 PM.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 03-13-2008, 03:49 AM
Registered User
 
Join Date: Feb 2008
Location: Longview, tx
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
tbi problems.....no start

OK, thanks for the info SNKBYT, I did take the fuel line loose and it was pumping gas but I didn't check the pressure. I will do that and let you know. I really appreciate the help. I don't want to sound stupid but what is a noid light???? Never heard the term.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 03-13-2008, 08:14 PM
snkbyt's Avatar
ASE Master
 

Last journal entry: Finished
Last photo:
Join Date: Mar 2002
Location: Salem, Oregon
Age: 61
Posts: 245
Wiki Edits: 0

Thanks: 1
Thanked 0 Times in 0 Posts
The injectors open and close so fast it can't be read on a voltmeter so you have to use a labscope or a noid light (strobe), flashes as the injector works. Also just because fuel comes out of the line doesn't mean it has pressure but if it does come out and shoots out good probably OK.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 03-21-2008, 04:31 PM
Registered User
 
Join Date: Feb 2008
Location: Longview, tx
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
tbi problems......won't start

OK guys, I went out to check fuel pressure but tried to crank it first. Would not start. Disconnected the fuel line to see what fittings I would need. While it was disconnected I thought I would check the volume flow again. I turned the key on and heard the fuel pump kick in. figured the pump would shut off but with the line open there was no pressure and it didn't. In the time from when I turned the key on, got out and saw gas, got in and turned the key off, it had filled one side of the tbi full. I reconnected the fuel line and waited until the extra gas disappeared and hit start. The truck started on the 2nd rev and ran better than it did before. I started it 5 times with 15-20 minutes between and it hit every time. I finally gave up and went to town to the beer store. I was gone 45 minutes. I started it again, no problem. It ran 30 secondss and died. Now , nothing. WT?????
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 03-21-2008, 06:55 PM
snkbyt's Avatar
ASE Master
 

Last journal entry: Finished
Last photo:
Join Date: Mar 2002
Location: Salem, Oregon
Age: 61
Posts: 245
Wiki Edits: 0

Thanks: 1
Thanked 0 Times in 0 Posts
FUEL PUMP! FUEL PUMP! FUEL PUMP! That's exactly how they act. stops on the bad spot then works OK.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 03-23-2008, 06:39 AM
Registered User
 
Join Date: Feb 2008
Location: Longview, tx
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
OK guys.............changed out the fuel pump and still no start. Is it time for the gallon of diesel and the match??????
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 03-23-2008, 11:35 AM
snkbyt's Avatar
ASE Master
 

Last journal entry: Finished
Last photo:
Join Date: Mar 2002
Location: Salem, Oregon
Age: 61
Posts: 245
Wiki Edits: 0

Thanks: 1
Thanked 0 Times in 0 Posts
Jerry does your truck have a 3 wire oil pressure sender? If it does jumper the 2 that have the same color wire and try it. I think the 88 uses oil pressure to shut down the pump in a wreck. If its a single wire sender this couldn't be the problem. Sender is right by the distributor. The fuel pump runs 3 seconds on 1st crank off the pump relay the swithes to oil pressure for continued run. Sorry the pump didn't fix it. Can't give up now.
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 03-26-2008, 12:06 PM
Registered User
 
Join Date: Feb 2008
Location: Longview, tx
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
tbi problems....won't start

Snkbyt, the oil pressure sensor is at the front left on this 454. the chilton book I have says the sender is pointed toward the back of the engine and says the unit beside it points to the left side, The unit pointing toward the back does not look like a sender and has two wires. The (what the book calls a fitting) unit that points to the left looks like the old chevy senders (abt 3" in diameter, 4" long, coming to a point where the wire connects. oh and it only has one wire.
Reply With Quote Quick reply to this message

Recent Electrical posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
crank no start meev182 Engine 7 06-17-2007 06:27 PM
1981 converted to 350 tbi info needed ghomer Engine 1 01-29-2007 10:15 PM
My truck wont start. 91 serria 350 tbi montea Engine 17 12-17-2006 04:23 PM
TBI fuel injector delay??? punk1c5040 Electrical 3 10-23-2004 10:11 PM
Very "lazy" '88 350 TBI help newsuburbanite Engine 9 12-01-2003 05:57 PM


All times are GMT -6. The time now is 12:44 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.