Engine Time to address the start and stall issue...

Gs1987GT · May 13, 2022

Hello Gents, good morning,

I figure its about time I address the start when cold, then stall issue. I believe it does this also when warm. Pretty much regardless of engine temp, the first time I crank it, it will start, then stall. If I crank again it starts and idles fine.

I plan on going through jrichker surging idle checklist.
As a preliminary step last night I disconnected the IAC and the car would not idle at all. Started and immediately stalled every time so the IAC must be functioning to some degree based on that.

I also hooked up a fuel pressure gauge last night and I have 38 psi fuel pressure when primed and running. Interesting thing was when I ran the engine up in rpm it looked like it was loosing fuel pressure? At least a few psi anyway. That does not seem right to me.

The car runs well m drives well and has good power. Maybe the gauge is wrong? A little miss at idle maybe, but I don't think these cars ever had a totally smooth idle.

Any thoughts on the start then stall issue would be appreciated. I want to address that first.

Have a good Friday guys...

General karthief · May 13, 2022

I'd be looking at the ignition switch under the dash, but I'm kinda strange so

Gs1987GT · May 13, 2022

Thanks general. Why do you suggest that? Just curious. It is original as far as I know...but I've never had a reason until now to check it.

Can you still get a motorcraft switch? It probably couldn't hurt to change it now just based on age if its original for maintenance purposes if nothing else and take it out of the equation.

Do you have to drop the column to access it?

Thanks.

Mustang5L5 · May 13, 2022

Gs1987GT said:
As a preliminary step last night I disconnected the IAC and the car would not idle at all. Started and immediately stalled every time so the IAC must be functioning to some degree based on that.

Your idle set screw is adjusted in too far. With the IAC unplugged, the engine should somewhat idle on it's own at a low rpm. It it stalls that means your idle is being purely maintained by IAC position and if it's slow to react or closes momentarity it will stall the engine.

Turn the idle screw in and start engine and unplug IAC. Engine will likely idle high. Back the screw out until the engine is maintaining a very low idle. Reset the ECU.

I would clean the IAC piston to make sure it's not sticking. plug it back in and retest.

General karthief · May 13, 2022

First you don't say what year the car is,
Second don't start changing parts just because a dimwit like me makes a suggestion, you need to inspect and test, I mention the ignition switch because you said it starts then shuts off then restarts and runs. The switch is a common issue with this symptom and the first item that activates the starting system. It also was a recall at some time in the fox bodies life. The key switch pushes a rod hooked to a spring loaded slide making contact with certain wire connectors and send power to things like primary/secondary ignition power, the starter and fuse box, the spring can lose it's tension, the rod can wear in the slide and the plastic part can separate from the switch body and wires can get loose and connections get heated and melt the connector.
These cars are 27+ years old, and things get loose/worn.
Like I stated, it's a starting point. When dealing with old cars I try to get things in working order, I don't know anything about your ride so all I can say is checking things out before hitting the boulevard to pick on ricers you need to know the bits that make up the workings are in working order.
Mike also posted above about the idle, that is another symptom to start/stall issues.
Tune ups, system checks like fuel pressure and spark condition are important items for older cars.

Gs1987GT · May 13, 2022

Mustsng 5L5, your advice is much appreciated and that makes perfect sense, i believe in your reply you meant to state the ,manual idle adjust screw is backed out too much as opposed to screwed in too much (which would increase idle rpm) but I understand where you are going and I will try that. Great advice as you so regularly offer here.

Reset the ECU, is there a procedure for that or disconnect the negative battery terminal and turn on the headlights for a few seconds? Or do you mean do a base idle reset? I know there is a procedure for that, I just have to search for it and find it here.

General, the car is the one in my signature, 1987 GT.
I understand not throwing parts at it, but if that switch is original and 34 yrs old it should probably be replaced for maintenance anyway.

I did a full tune on the car last year when I had the lower intake off to fix an oil leak, new plugs, wires, cap. Rotor, coil, has an msd blaster coil, new fuel and air filters last fall, all those items should be in good shape and addressed.

As I said, for a stock engine, it pulls hard and runs strong and is responsive, except for the initial stall on first start issue.

Thanks again.

General karthief · May 13, 2022

Help me create the "Surging Idle Checklist"

Updated 26-Oct-2019 to clarify creeping idle RPM increase as the car is being driven. Many of you are familiar with the "Cranks OK, but No Start Checklist for Fuel Injected Mustangs" checklist and the No Crank Checklist. They are very effective in finding and eliminating the problems by use of...

forums.stangnet.com

This gives info on what check and procedures for reseting the computer and other important stuff.

Gs1987GT · May 13, 2022

General karthief said:
Help me create the "Surging Idle Checklist"

Updated 26-Oct-2019 to clarify creeping idle RPM increase as the car is being driven. Many of you are familiar with the "Cranks OK, but No Start Checklist for Fuel Injected Mustangs" checklist and the No Crank Checklist. They are very effective in finding and eliminating the problems by use of...

forums.stangnet.com

This gives info on what check and procedures for reseting the computer and other important stuff.

Much appreciated as always general, thank you!

Gs1987GT · May 15, 2022

Update:

I knew the prior owner replaced the IAC because it is not original and appears relatively new so I didn't remove/ clean it, yet.

I did go in on the manual idle adjustment screw until it would idle with the IAC unplugged as 5l5 suggested (thank you!). I then got the engine up to operating temp, checked engine timing with spout removed and that was still ok, about 14 degrees initial.

I then checked and adjust TPS voltage, my range of the sensor adjustment was .711 to .930 VDC, so I went for around the middle of that range, .830 VDC.

I always keep the positive battery cable disconnected when I'm not driving the car, but I did reset the ecu agsin by disconnecting and then turning on the headlight switch for awhile.

As I was adjusting everything, on a few starts then engine did fire and it did not stall, but it surged/ hunted a bit until it settled into an idle.

When I was done with all adjustments it started and settled into an idle in a few seconds of running just as it should with no hunting.

So it seems to be good for now. I'm sure I've got some other issues going on I have to delve further into because the car seems happiest idling just under 1,000 rpm. Probably too fast for some but doesn't bother me at all and it runs very good otherwise so I'm not going to mess with it for now. The autozone alternator I installed last year doesn't charge as strongly as I'd prefer (still 14.25 VDC at idle, but I notice a drop on the gauge at night when sitting at a traffic light) so a slightly increased idle rpm isn't a negative thing in my case.

In a few years I'd like to pull it anyway, do a 347 stroker and put a procharger on it and at that point I'll have to decide if I want to stay with the stock (convert to mass air) Ford ecu or go to an aftermarket set up.

Thanks to @Mustang5L5 and @General karthief for your continued great help and advice on this forum. I (and we all) really appreciate it.

Have a good Sunday gents.....

limp · May 15, 2022

You are supposed to disconnect the neg cable NOT the positive....
Can't say in your car, but I have had GM vehicles that had the battery disconnected, that took a few days to retrain the computer after reconnecting the battery and driving them....

General karthief · May 15, 2022

Don't thank me, I just regurgitate what I've learned around here.
Another satisfied customer non the less
Now you have to post some pics of this ride.
Extra credit for WHEELIES!!!

Gs1987GT · May 15, 2022

limp said:
You are supposed to disconnect the neg cable NOT the positive....
Can't say in your car, but I have had GM vehicles that had the battery disconnected, that took a few days to retrain the computer after reconnecting the battery and driving them....

Not sure about that limp. I was always taught to connect the negative first and disconnect it last so the system stays grounded.

I don't think it's a big deal either way though...it's just what I do

Gs1987GT · May 15, 2022

General karthief said:
Don't thank me, I just regurgitate what I've learned around here.
Another satisfied customer non the less
Now you have to post some pics of this ride.
Extra credit for WHEELIES!!!

Can't agree with that sir. You are always very helpful to others and very active on here and provide good advice.

Your efforts here are appreciated sir.

General karthief · May 15, 2022

Bumbling Genius
The real melvin here is Mike (Mustang5L5)

Engine Time to address the start and stall issue...

Gs1987GT

Active Member

General karthief

wonder how much it would cost to ship you a pair

Gs1987GT

Active Member

Mustang5L5

That is…until I whipped out my Bissell

General karthief

wonder how much it would cost to ship you a pair

Gs1987GT

Active Member

General karthief

wonder how much it would cost to ship you a pair

Help me create the "Surging Idle Checklist"

Gs1987GT

Active Member

Help me create the "Surging Idle Checklist"

Gs1987GT

Active Member

limp

wrap a little cheese around it and its a done

General karthief

wonder how much it would cost to ship you a pair

Gs1987GT

Active Member

Gs1987GT

Active Member

General karthief

wonder how much it would cost to ship you a pair

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Engine Time to address the start and stall issue...

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wonder how much it would cost to ship you a pair

Active Member

wonder how much it would cost to ship you a pair

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Active Member

wrap a little cheese around it and its a done

wonder how much it would cost to ship you a pair

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wonder how much it would cost to ship you a pair

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