Not Running Good!? -

Go Back > Ford Mustang Tech > 5.0L (1979-1995) Mustang
Sign in using an external account
Register Forgot Password?

5.0L (1979-1995) Mustang Technical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.
Sponsored by Weld Racing

Welcome to Mustang Forums!
Welcome to Mustang Forums.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

Not Running Good!?

Thread Tools Search this Thread
Old 10-27-2013, 02:42 PM   #1
Join Date: Oct 2013
Vehicle: 94, ford,mustang gt
Location: ky
Posts: 8
Default Not Running Good!?

I purchased a 1994 Mustang with efi to carb swap recently. It has a Mr. Gasket fuel pump edelbrock intake and 1405 carb. Couple issues Im running into, its running very rough at idle and spitting and sputtering under a load. The carb is adjusted to the best of my ability and is running about 4.5psi fuel. Also vacuum advance when advance when hooked up kills the engine? So its plugged at the moment. Any ideas?? Im stumped
This ad is not displayed to registered or logged-in members.
Register your free account today and become a member on Mustang Forums!
uavspecialist is offline   Reply With Quote
Old 10-27-2013, 03:39 PM   #2
Join Date: Oct 2013
Vehicle: 94, ford,mustang gt
Location: ky
Posts: 8

Also It seems to do this once its been running for a while
uavspecialist is offline   Reply With Quote
Old 10-28-2013, 04:56 AM   #3
4th Gear Member
Join Date: Nov 2006
Vehicle: '98 3.8L Mustang Convertible
Location: CA
Posts: 1,671

Its been a while since I’ve worked on a carb’d motor, but I usually started with cleaning the carb. A (partially) clogged jet and/or clogged fuel filter could cause the problems your talking about. Good luck...
'98 3.8L Convertible (Red w/ White top)
’07 Shelby GT500 (White w/ Blue racing stripes)
YouTube Channel: Pet Rock’s Garage
petrock is offline   Reply With Quote
Old 10-28-2013, 06:10 AM   #4
5th Gear Member
Join Date: Jul 2012
Vehicle: 1990 lx hatch 5.0
Location: ohio
Posts: 2,917

You need to check to see where you timing is set to at the moment.
If the engine dies when you hook up the vacuum advance , the base timing may be set to high.
If some one disconnected the vacuum advance , the distributor would need to be manually advanced in order to maintain idle . This will kill performance because the mechanical and vacuum advance are supposed to work in unison with one another to maintain an optimal level of timing advance over the entire rpm range. Part throttle or idle = higher vacuum advance and better throttle response. With no vacuum advance and an overly advanced dizzy as soon as you apply rmps to the engine the mechanical advance starts to work and puts you way to far advanced for the amount of fuel and air coming in, this will kill your performance and may cause detonation.

You need to time the car so that you can hook up the vacuum advance and maintain an idle of about 750 to 800 rpm. You could probly increase fuel pressure to about 6 psi If it runs a bit rich you can back it down a bit but I think 4.5 psi is a bit low for that carb. Most carb pumps are factory set at 7.5 psi and usually that is a bit much. The edelbrock carbs tend to run some what rich any ways out of the box , they make a spring kit to adjust the primaries and lean it out a bit.
dawson1112 is online now   Reply With Quote
Old 10-28-2013, 03:54 PM   #5
Join Date: Oct 2013
Vehicle: 94, ford,mustang gt
Location: ky
Posts: 8

Will do, I need to get my hands on a timing light and vacuum to really tune it well.
uavspecialist is offline   Reply With Quote
Old 10-28-2013, 03:54 PM
Ford Mustang

Paid Advertisement


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not 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

Forum Jump


Featured Sponsors
Vendor Directory
New Sponsors
All times are GMT -5. The time now is 12:06 AM.

© Internet Brands, Inc.

This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. Ford® is a registered trademark of the Ford Motor Company
Emails Backup