TBI fuel delivery problem when starting - Page 2 - 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> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #16 (permalink)  
Old 04-18-2013, 05:59 PM
LATECH's Avatar
Hotrodders.com Moderator
 

Last journal entry: Motor - vator
Last photo:
Join Date: Jul 2010
Location: Northeast Pennsylvania
Posts: 5,166
Wiki Edits: 0

Thanks: 199
Thanked 249 Times in 231 Posts
Here is a pinout on the 8 pin HEI/EFI module for TBI setups with small cap dizzy
Attached Thumbnails
Click image for larger version

Name:	hei8-ms2.png
Views:	270
Size:	44.6 KB
ID:	73300  

    Advertisement
__________________
Fact is stranger than Fiction
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #17 (permalink)  
Old 04-18-2013, 06:01 PM
LATECH's Avatar
Hotrodders.com Moderator
 

Last journal entry: Motor - vator
Last photo:
Join Date: Jul 2010
Location: Northeast Pennsylvania
Posts: 5,166
Wiki Edits: 0

Thanks: 199
Thanked 249 Times in 231 Posts
If this were mine, I would try another Ignition module.
__________________
Fact is stranger than Fiction
Reply With Quote Quick reply to this message
  #18 (permalink)  
Old 04-18-2013, 09:18 PM
Registered User
 
Join Date: Nov 2011
Location: Phoenix,
Posts: 26
Wiki Edits: 0

Thanks: 4
Thanked 0 Times in 0 Posts
Wow, that is some pretty heavy advice. I have a grasp of what you guys are telling me, but you certainly have the technology down better than I do. I'll try the test bulb and see if I am getting the signal.

Thanks to everyone for sharing your knowledge and talents. I'll let you know how it turns out.

Fleetsidebob
Reply With Quote Quick reply to this message
  #19 (permalink)  
Old 04-19-2013, 09:38 AM
Registered User
 
Join Date: Nov 2011
Location: Phoenix,
Posts: 26
Wiki Edits: 0

Thanks: 4
Thanked 0 Times in 0 Posts
I take it that the pick up coil is actually inside the distributor cap and that it is different from the external coil? When you speak of replacing the module, are you talking about the pick up coil?
Reply With Quote Quick reply to this message
  #20 (permalink)  
Old 04-19-2013, 09:54 AM
Registered User
 
Last wiki edit: Wheelbase database Last photo:
Join Date: Jan 2007
Location: Virginia
Posts: 3,516
Wiki Edits: 1

Thanks: 6
Thanked 144 Times in 131 Posts
Quote:
Originally Posted by fleetsidebob View Post
When I turn the key to the run position, the fuel pump runs for a couple of seconds and shuts off. I was assuming it stopped running because it was pressured up.
This is normal. In a factory TBI system, there are two separate methods for operating the fuel pump. When you turn the key to START, the ECU closes the fuel pump relay for two seconds to build pressure in the system. This is the only time that the fuel pump relay is used. Once the engine is cranking and builds fuel pressure, a separate circuit closes through the oil pressure switch. This bypasses the relay and keeps the pump running whenever there is oil pressure.

Quote:
How can I test to see if there is actually pressure at the injectors during start up? I hate to disconnect fuel lines and have gas shooting all over the place.
The only way to test this is to temporarily attach a fuel pressure gauge to the test port on the fuel line to the throttle body. You should see ~15 psi when you turn the key to START. The pressure should remain there the whole time you are cranking the engine. If it drops, you have a problem someplace, like a bad check valve in the pump or a bad pressure regulator.

Quote:
The pump itself is not very accessable, but I'm wondering if I could use a clamp meter around the power wire to the fuel pump and see if we have current while the starter is turning. Would that make sense?
No. See above. If the problem is a check valve the pump will run but you won't maintain pressure in the system, so an ammeter won't help.
Reply With Quote Quick reply to this message
The Following User Says Thank You to joe_padavano For This Useful Post:
fleetsidebob (04-19-2013)
  #21 (permalink)  
Old 04-19-2013, 09:55 AM
Registered User
 
Last photo:
Join Date: Apr 2007
Location: Seattle, Wa
Posts: 6,684
Wiki Edits: 0

Thanks: 3
Thanked 403 Times in 348 Posts
Quote:
Originally Posted by fleetsidebob View Post
When I turn the key to the run position, the fuel pump runs for a couple of seconds and shuts off. I was assuming it stopped running because it was pressured up.

How can I test to see if there is actually pressure at the injectors during start up? I hate to disconnect fuel lines and have gas shooting all over the place.

The pump itself is not very accessable, but I'm wondering if I could use a clamp meter around the power wire to the fuel pump and see if we have current while the starter is turning. Would that make sense?
The pump should run from 10 to 15 seconds. What's going on is a pump shut down by the computer if in that time if the computer doesn't see the RPMs coming up from a sucessful start. Additionally, there is a relay on the firewall that can fail. You need to get a wire diagram to checck all this out. There are minor differences of how this curcuit is layed out that appear year to year, model to model.

If it's a sensing problem often the engine can be started with a prime and it will continue running, if it's a relay problem it will burn the prime then stop running.

You can force the issue by jumpering around the relay but then you've got to be sure that if the key is in run position, the engine better damn well also be actually running.

Bogie
Reply With Quote Quick reply to this message
The Following User Says Thank You to oldbogie For This Useful Post:
fleetsidebob (04-19-2013)

Recent Engine 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
fuel delivery problem on older 350 chevy SGT@ARMS Engine 6 01-31-2012 08:14 PM
fuel delivery problem with chevy 350 mb1d357 Engine 5 12-01-2008 09:40 PM
fuel delivery problem meev182 Engine 1 03-20-2008 07:25 PM
Fuel delivery problem, anyone knowledgeable on this? PLEASE HELP! dripcandles Engine 7 09-28-2006 10:57 AM
fuel delivery problem has me stumped dripcandles Engine 4 05-16-2006 01:54 PM


All times are GMT -6. The time now is 02:23 AM.


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.