1991 Ford Mustang - Mustang Evolution

Go Back   Mustang Evolution > 1979-2015 Mustang GT || Tech and Talk > 1979-1995 Mustang GT



Reply
 
Thread Tools Search this Thread
Please support our sponsors and let them know you heard about them here!
Old 12-19-2015, 09:35 AM   #1
Registered User
Newbie
 
Join Date: Dec 2015
Location: Odessa
Region: Texas
Posts: 3
1991 Ford Mustang

Need help! I have a 91 fox and the dies when i give it gas
The car had been sitting for a couple of years.. I replaced the fuel filter and fuel pump and cleaned out the gas tank and put new gas?? Any ideas what I could be Click image for larger version

Name:	ImageUploadedByMustang Evolution1450539335.891404.jpg
Views:	110
Size:	95.6 KB
ID:	194981


Sent from my iPhone using Mustang Evolution
Josueb_8 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 12-19-2015, 09:58 AM   #2
Registered Member

Regular
 
Join Date: Jun 2015
Location: Spokane
Region: Washington
Posts: 1,597
Wow......diagnosing this over the Internet is just about as hard as doing dentistry over the Internet..........it could be one of several hundred things. You replaced almost everything I would have suggested...........maybe replace the plugs too?
The folks here are going to need more info. What engine, miles on car, what transmission?
Guard 5.0 is offline   Reply With Quote
Old 12-19-2015, 11:33 AM   #3
Registered Member
Regular
 
Join Date: Mar 2013
Location: Salinas
Region: California
Posts: 7,417
Yes. It is difficult to diagnose problems like this over the internet.

Does everything seem to be in good condition under the hood? No evidence of rodent damage or anything like that?
When you say that the engine dies when you give it gas, do you mean that it starts up and idles normally, but when you step on the gas pedal the engine dies?
straybullitt is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 12-20-2015, 10:34 PM   #4
Registered User
Newbie
 
Join Date: Dec 2015
Location: Odessa
Region: Texas
Posts: 3
Yes it starts up normal and it dies down when you give it gas
Sorry the engine has maybe less then 300 since rebuild its a 5.0 and I think it has the t5


Sent from my iPhone using Mustang Evolution
Josueb_8 is offline   Reply With Quote
Old 12-20-2015, 10:48 PM   #5
Registered Member
Regular
 
wbrockstar's Avatar
 
Join Date: Mar 2015
Location: Nashville
Region: Tennessee
Posts: 289
The first thing I would do is check for vacuum leaks,since a hose could be dry rotted from sitting so long.Take the tip off the end of a handheld propane torch,attach a 1' long piece of hose and attach it to the propane torch gas valve.Start the engine & let it idle,open the torch valve so propane comes out then run the hose over everything that gets vacuum like vacuum hoses,intake gaskets,fuel injector ports on the intake,egr evp & IAC gaskets,etc.If the idle suddenly surges up,youve found the leak.Check the fuel pressure regulator & make sure its not leaking.While the engines idling,remove the vacuum hose from it,see if the hose has fuel in it & see if fuel is seeping out of the regulator vacuum port.If either part has fuel coming out,the regulator is bad.If its leaking internally,that will cause the o2's to read rich.When they read rich,the EEC will lower injector pulse & that could cause hesitation & stalling.If the regulator is stuck open,the fuel pump won't be able to keep the injectors supplied with enough pressure so the car will hesitate or stall.
Check the throttle body to see if its heavily coated with carbon buildup,if so clean it because it can cause the throttle plate to stick.
Check the egr valve to make sure its not stuck open.The egr valve should only open during part throttle(cruise)conditions,so if its open during idle,acceleration,wot or deacceleration,the valve is malfunctioning.When the egr is open,the EEC leans the fuel mixture & advances timing & you dont need these things to happen during idle or acceleration.It will cause hesitation & stalling.If its stuck open during idle,remove the vacuum hose from it.Did idle change??If yes,the evr solenoid is malfunctioning.If idle didnt change,the egr valve is dirty or defective.
Test the TPS with a voltmeter.It shouldn't have any dead spots or spikes,if it does its defective.This link will help.
TPS Codes 23/53/63 Troubleshooting
__________________
91 LX 342ci(10.5:1)
TFS 190cc(stage ll)
TFS track heat
XE276HR .544" .544"
Flowtech 1 3/4"
Prochamber w FM
wbrockstar is offline   Reply With Quote
Old 12-20-2015, 11:05 PM   #6
Registered Member
Regular
 
Join Date: Mar 2013
Location: Salinas
Region: California
Posts: 7,417
Scan for any diagnostic trouble codes. Hopefully, there is something to help point you in the right direction.
If there are no codes present, I would start by carefully inspecting every electrical connection that would need to be disconnected during the engine removal/replacement process. Since the engine was installed not too many miles ago, possibly something has become loose, or was never reconnected properly. And if the engine replacement was done by an unknown person, you might want to double check that the intake manifold bolts are all properly torqued. They can become loose after a few hundred miles.
Check all of the obvious things first.

Also, after you replaced the fuel pump, did you verify that the fuel system is operating correctly by testing it with a fuel pressure tester?
straybullitt is offline   Reply With Quote
Old 12-20-2015, 11:17 PM   #7
Registered Member
Regular
 
Join Date: Mar 2013
Location: Salinas
Region: California
Posts: 7,417
Quote:
Originally Posted by wbrockstar View Post
The first thing I would do is check for vacuum leaks,since a hose could be dry rotted from sitting so long.Take the tip off the end of a handheld propane torch,attach a 1' long piece of hose and attach it to the propane torch gas valve.Start the engine & let it idle,open the torch valve so propane comes out then run the hose over everything that gets vacuum like vacuum hoses,intake gaskets,fuel injector ports on the intake,egr evp & IAC gaskets,etc.If the idle suddenly surges up,youve found the leak.Check the fuel pressure regulator & make sure its not leaking.While the engines idling,remove the vacuum hose from it,see if the hose has fuel in it & see if fuel is seeping out of the regulator vacuum port.If either part has fuel coming out,the regulator is bad.If its leaking internally,that will cause the o2's to read rich.When they read rich,the EEC will lower injector pulse & that could cause hesitation & stalling.If the regulator is stuck open,the fuel pump won't be able to keep the injectors supplied with enough pressure so the car will hesitate or stall.
Check the throttle body to see if its heavily coated with carbon buildup,if so clean it because it can cause the throttle plate to stick.
Check the egr valve to make sure its not stuck open.The egr valve should only open during part throttle(cruise)conditions,so if its open during idle,acceleration,wot or deacceleration,the valve is malfunctioning.When the egr is open,the EEC leans the fuel mixture & advances timing & you dont need these things to happen during idle or acceleration.It will cause hesitation & stalling.If its stuck open during idle,remove the vacuum hose from it.Did idle change??If yes,the evr solenoid is malfunctioning.If idle didnt change,the egr valve is dirty or defective.
Test the TPS with a voltmeter.It shouldn't have any dead spots or spikes,if it does its defective.This link will help.
TPS Codes 23/53/63 Troubleshooting
I have never heard of using a propane torch to locate vacuum leaks. But why not! Lol
I suppose that the only thing that you would need to be careful of is, if there was an open spark from a leaky wire, and if the propane built up enough... You could possibly lose your facial hair.
straybullitt is offline   Reply With Quote
Old 12-21-2015, 06:20 AM   #8
Registered Member
Regular
 
wbrockstar's Avatar
 
Join Date: Mar 2015
Location: Nashville
Region: Tennessee
Posts: 289
Quote:
Originally Posted by straybullitt View Post
I have never heard of using a propane torch to locate vacuum leaks. But why not! Lol
I suppose that the only thing that you would need to be careful of is, if there was an open spark from a leaky wire, and if the propane built up enough... You could possibly lose your facial hair.
Cover the spark plug wires up with a damp towel where they feed off the distributer cap.The remaining portion of them will be down on the plugs away from most of the areas you'll be testing.

Fuel Injection Technical Library ยป Vacuum Leaks
__________________
91 LX 342ci(10.5:1)
TFS 190cc(stage ll)
TFS track heat
XE276HR .544" .544"
Flowtech 1 3/4"
Prochamber w FM
wbrockstar is offline   Reply With Quote
Old 12-27-2015, 02:30 PM   #9
Registered Member
Regular
 
havhammer's Avatar
 
Join Date: Oct 2011
Region: Michigan
Posts: 127
You can also use a can of carb cleaner with the straw on it, instead of propane. Also disconnect the mass air sensor and start it and try to accelerate. If you can or it improves it your mass air sensor is bad or the sensor wire is dirty. I would start there first.

Sent from my SPH-L710 using Mustang Evolution mobile app
havhammer is online now   Reply With Quote
Reply

Lower Navigation
Go Back   Mustang Evolution > 1979-2015 Mustang GT || Tech and Talk > 1979-1995 Mustang GT

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 On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Mean green 91 :: 1991 Ford Mustang Mean green 91 Member Garages 5 11-15-2015 08:59 PM
My 1991 Ford Mustang 5.0 GT 5.0 pony 1979-1995 Mustang GT 16 05-10-2011 05:26 PM

» Like Us On Facebook



04:09 PM


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0

MustangEvolution.com is in no way associated with or endorsed by Ford Motor Company.