Engine Starts then stalls Surging idle

[Luisr010]

need help my mustang is stalling.
It’s a 1987 ttop Mustang GT.
It starts and surges high for a second then low rpm bouncing until it dies.
So far what I’ve done:
Fuel pump, Fuel pump relay, Fuel tank, fuel filter,
Fuel pressure regulator, tfi module, egr valve.

Took off my intake to and inspected all the hoses.
I get 30 psi at the rail at the front.
I spray starter fluid after the maf a little bit and it
Evens out and runs nice. Then it stumbles and stalls again.
I’m all out of idea I need HELP please.

 

[Luisr010]

need help my mustang is stalling.
It’s a 1987 ttop Mustang GT.
It starts and surges high for a second then low rpm bouncing until it dies.
So far what I’ve done:
Fuel pump, Fuel pump relay, Fuel tank, fuel filter,
Fuel pressure regulator, tfi module, egr valve.

Took off my intake to and inspected all the hoses.
I get 30 psi at the rail at the front.
I spray starter fluid after the maf a little bit and it
Evens out and runs nice. Then it stumbles and stalls again.
I’m all out of idea I need HELP please.

I get 42 psi on the rail then it goes to 30 when the pump shuts down in the on position key

 

[AeroCoupe]

Define how you are checking the fuel pressure. Stock fuel pressure should be 38-39 psi with the vacuum line disconnected from the fuel pressure regulator (FPR) and the vacuum line plugged. With the vacuum line connected the pressure should be around 30 psi (+/- 1 psi). Checking the pressure with the vacuum line connected requires the car to be running. I think that is pretty obvious but wanted to point it out just in case.

Have you pulled the codes on the car yet? 1987 & 1988 cars do not have check engine lights (CEL) so you have no indication on the dash if codes are present.

Electrical - How To Pull Codes From EEC-IV In 86- 95 5.0 Mustangs

@Noobz347 - The code dump procedure isn't in the sticky - you may want to add it... Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on. Dumping the computer diagnostic codes on 86-95 Mustangs Revised 26-July-2011. Added need to make sure the clutch is...

stangnet.com

 

[Luisr010]

Define how you are checking the fuel pressure. Stock fuel pressure should be 38-39 psi with the vacuum line disconnected from the fuel pressure regulator (FPR) and the vacuum line plugged. With the vacuum line connected the pressure should be around 30 psi (+/- 1 psi). Checking the pressure with the vacuum line connected requires the car to be running. I think that is pretty obvious but wanted to point it out just in case.

Have you pulled the codes on the car yet? 1987 & 1988 cars do not have check engine lights (CEL) so you have no indication on the dash if codes are present.

Electrical - How To Pull Codes From EEC-IV In 86- 95 5.0 Mustangs

@Noobz347 - The code dump procedure isn't in the sticky - you may want to add it... Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on. Dumping the computer diagnostic codes on 86-95 Mustangs Revised 26-July-2011. Added need to make sure the clutch is...

stangnet.com

I checked with a gauge hooked on to the fuel rail at the front. Just changed a 255 walbro into the car along with a brand. New fuel tank.

On position codes: 81o 82o 95o 81o 10o
With car on: 21r 41r 91r 33r

My car was running fine it just one day decided to stall at a red light all of a sudden.

 

[AeroCoupe]

Was the stall before or after the installation of the new pump?

Key On Engine Off (KOEO):
81 - Air Management 2 (AM2) circuit failure
82 - Air Management 1 (AM1) circuit failure
95 - Fuel pump secondary circuit failure
Key On Engine Running (KOER):
21 - ECT out of Self-Test Range
33 - EGR valve opening not detected
41 - HEGO sensor circuit indicates system lean (right HEGO)
91 - HEGO sensor circuit indicates system lean (left HEGO)
The codes are pointing that direction but you may have deleted a few things and/or the car is a 4 cylinder to V8 swap (code 95) and there are other issues due to a poor swap. 81 & 82 are the TAB solenoids related to the EGR so those combined with 33 leads me to believe all that has been deleted.

21 needs to be addressed as the ECU uses this info for trimming the fuel. 41 and 91 need to be addressed as well as these also contribute to how the ECU trims the fuel.

ECU could have an issue as is could be as old as 36 years if original and if a swap car then it could be a few years less. Several threads on here about the caps in the ECU's going bad and sending them off to ECU Exchange for repair. Cost is around $150.

Ford

Repair Service for Ford ECUs

www.theecuexchange.com

If you have access to another speed density (assuming the car is non-mass air) ECU try swapping them out and see if this clears up the problem. You need to be damn sure all the wiring it correct or you could damage another ECU.

 

[Luisr010]

Was the stall before or after the installation of the new pump?

Key On Engine Off (KOEO):
81 - Air Management 2 (AM2) circuit failure
82 - Air Management 1 (AM1) circuit failure
95 - Fuel pump secondary circuit failure
Key On Engine Running (KOER):
21 - ECT out of Self-Test Range
33 - EGR valve opening not detected
41 - HEGO sensor circuit indicates system lean (right HEGO)
91 - HEGO sensor circuit indicates system lean (left HEGO)
The codes are pointing that direction but you may have deleted a few things and/or the car is a 4 cylinder to V8 swap (code 95) and there are other issues due to a poor swap. 81 & 82 are the TAB solenoids related to the EGR so those combined with 33 leads me to believe all that has been deleted.

21 needs to be addressed as the ECU uses this info for trimming the fuel. 41 and 91 need to be addressed as well as these also contribute to how the ECU trims the fuel.

ECU could have an issue as is could be as old as 36 years if original and if a swap car then it could be a few years less. Several threads on here about the caps in the ECU's going bad and sending them off to ECU Exchange for repair. Cost is around $150.

Ford

Repair Service for Ford ECUs

www.theecuexchange.com

If you have access to another speed density (assuming the car is non-mass air) ECU try swapping them out and see if this clears up the problem. You need to be damn sure all the wiring it correct or you could damage another ECU.

Hello, thank you and the emissions is deleted it doesn’t have cats. And my engine is off a 1989 it is not original has been rebuilt but what is strange is one day it started stalling out of no where. Mine has a mass air

 

[Luisr010]

Was the stall before or after the installation of the new pump?

Key On Engine Off (KOEO):
81 - Air Management 2 (AM2) circuit failure
82 - Air Management 1 (AM1) circuit failure
95 - Fuel pump secondary circuit failure
Key On Engine Running (KOER):
21 - ECT out of Self-Test Range
33 - EGR valve opening not detected
41 - HEGO sensor circuit indicates system lean (right HEGO)
91 - HEGO sensor circuit indicates system lean (left HEGO)
The codes are pointing that direction but you may have deleted a few things and/or the car is a 4 cylinder to V8 swap (code 95) and there are other issues due to a poor swap. 81 & 82 are the TAB solenoids related to the EGR so those combined with 33 leads me to believe all that has been deleted.

21 needs to be addressed as the ECU uses this info for trimming the fuel. 41 and 91 need to be addressed as well as these also contribute to how the ECU trims the fuel.

ECU could have an issue as is could be as old as 36 years if original and if a swap car then it could be a few years less. Several threads on here about the caps in the ECU's going bad and sending them off to ECU Exchange for repair. Cost is around $150.

Ford

Repair Service for Ford ECUs

www.theecuexchange.com

If you have access to another speed density (assuming the car is non-mass air) ECU try swapping them out and see if this clears up the problem. You need to be damn sure all the wiring it correct or you could damage another ECU.

I have put starting fluid a little in the maf and it evens out and runs perfect but as soon as it runs out it starts to stumble again.

 

[AeroCoupe]

You need to address the oxygen sensors and ECT issues.

If it were me I would be suspecting the ECU.

 

[General karthief]

Or a big vacuum leak

 

[Luisr010]

You need to address the oxygen sensors and ECT issues.

If it were me I would be suspecting the ECU.

How do I know if the ecu is no good?

 

[Luisr010]

You need to address the oxygen sensors and ECT issues.

If it were me I would be suspecting the ECU.

The ECT wouldn’t it be because the car hasn’t reach operating temperature? Since I’m only able to start it cold?

 

[Luisr010]

Or a big vacuum leak

Other than the intake losing vaccum there’s no other location right? That I would be concerned about

 

[Luisr010]

Other than the intake losing vaccum there’s no other location right? That I would be concerned about

I have capped most of the hoses since I don’t have ac or emissions system or cats

 

[AeroCoupe]

Remove the cover on tbe ECU and check the blue capacitors as they seem to corrode, burn, or the end looks like it’s popped up/swollen. Also check for burnt traces. Lots of threads on here covering the topic.

 

[Luisr010]

Remove the cover on tbe ECU and check the blue capacitors as they seem to corrode, burn, or the end looks like it’s popped up/swollen. Also check for burnt traces. Lots of threads on here covering the topic.

Not burned or corrode or swollen so ecu is good?

 

[AeroCoupe]

Possibly but the visual check is encouraging.. The only way I know to test one for sure is with a break out box or sending it off to someone that can test / rebuild it.

The code 95 is bothersome. Read through this thread:

Code 95. What is considered the Secondary fuel pump circuit

So I have the legendary stumble, hiccup, misfire... what ever you wanna call it issue. Comes up with code 95. So what is considered the "secondary fuel pump circuit" vs primary. The only other codes are egr. 93 LX 5.0 T5

stangnet.com

 

[Luisr010]

I’m going to search that tomorrow thank you

 

[Luisr010]

Possibly but the visual check is encouraging.. The only way I know to test one for sure is with a break out box or sending it off to someone that can test / rebuild it.

The code 95 is bothersome. Read through this thread:

Code 95. What is considered the Secondary fuel pump circuit

So I have the legendary stumble, hiccup, misfire... what ever you wanna call it issue. Comes up with code 95. So what is considered the "secondary fuel pump circuit" vs primary. The only other codes are egr. 93 LX 5.0 T5

stangnet.com

Thank you so much for you help I Appreciate you replying!! And my car was running fine it ran from Kentucky to Florida after that I did an oil change and some brake swap and a strut brace And cleaned the interior. I went to pick up tires and on my way back at a light it stumbled and stalled and ever since then it stalls and dies

 

[Mustang5L5]

If the engine isn’t fully warmed up you would get a code 21.

Also, do a smoke test for vac leaks as speed density cars are very sensitive to them.

 

[AeroCoupe]

@Mustang5L5 - I believe his car is a mass air conversion so is there anything with that that would trip a Code 95? The smoke test is a great suggestion.

Building your own smoke generator is pretty easy and here are two versions:

Using an air compressor:

View: https://www.youtube.com/watch?v=crc6CJ_ni2w

Using a small air pump if you do not have an air compressor:

View: https://www.youtube.com/watch?v=u6KmRZh8IXE