Brake issues again smh

Ybfav84 · Mar 8, 2025

So I’m almost done I hope this is the last time.
I keep running into issues.
1984 mustang 5.0 did a 5 lug
Rear 1995 GT diff and brakes and front 04 cobra spindles and brakes.
1993 booster and 1993 mc
Now I’m running into an issue when I press on the brakes the car wants to stall
Is it a vacuum line making this issue?

AeroCoupe · Mar 8, 2025

Check the cruise control switch under the dash and check for codes.

Post in thread 'Foxbody Mustang Cruise Control information, location, wiring diagrams'

Jan 22, 2021

EDIT: POST BORROWED BY MUSTANG5L5 to add more content. Sorry General

Cruise control brake cancel vacuum dump valve

One common failure mode of the cruise system is misadjustment of the vacuum dump valve on the brake pedal

The above is from an 87 thunderbird, but fox mustang is similar. Tje valve is ALWAYS OPEN to atmosphere unless the brake pedal arm is in contact with the yellow plunger on the bottom, which closes the valve. This allows the servo to build and hold vacuum, which is how it moves the throttle blade open and close.

When you tap the brake pedal...

90sickfox · Mar 9, 2025

Usually, a vacuum leak would cause the car to idle up, not stall. If you hear a hissing noise while the car is running and lightly pressing the brake then you have a booster vacuum leak. To test a vacuum leak you could disconnect the vacuum to the booster and plug the hose. The brakes will be hard to press but if you press them, and car doesn't cut off, you are in the right path. What rpm is your idle set at ? What transmission do you have in the car ?

Bullitt347 · Mar 9, 2025

90sickfox said:
Usually, a vacuum leak would cause the car to idle up, not stall. If you hear a hissing noise while the car is running and lightly pressing the brake then you have a booster vacuum leak. To test a vacuum leak you could disconnect the vacuum to the booster and plug the hose. The brakes will be hard to press but if you press them, and car doesn't cut off, you are in the right path. What rpm is your idle set at ? What transmission do you have in the car ?

OP has an 84, it would have a carb.
A large enough vacuum leak, like from a booster would likely cause the engine to stall.

limp · Mar 9, 2025

Bullitt347 said:
OP has an 84, it would have a carb.
A large enough vacuum leak, like from a booster would likely cause the engine to stall.

As a younger person I forgot to plug my PCV valve back in the valve cover... The car died at every stoplite until I found someone to help me lift off the hood to see what was wrong.... No hinges on this model....

Noobz347 · Mar 9, 2025

Is it a new or used booster?

Did you test it before install?

Ybfav84 · Mar 9, 2025

I’m sorry everyone I was trippin
Turns out it was stalling bc it was on jackstands
I was just too excited to get it off jackstands after 6 months that’s why I didn’t think about that
Thank you everyone for the help

DR1962 · Mar 10, 2025

Ybfav84 said:
I’m sorry everyone I was trippin
Turns out it was stalling bc it was on jackstands
I was just too excited to get it off jackstands after 6 months that’s why I didn’t think about that
Thank you everyone for the help

It happens. I put a 289 and a C4 in a Mustang II ( don't hate me ) when I set it down I drove to a friends house. When I was driving back home a could see two trails of oil in the other lane. Right about then that trans started slipping. When I got back in the garage I had the tans lines on the radiator but the clamps were just hanging their. I never tightened them. But dumb luck is the best luck so no harm to the trans. LOL

Brake issues again smh

Ybfav84

Member

AeroCoupe

lube between the nut and the face. I know my lubes

Post in thread 'Foxbody Mustang Cruise Control information, location, wiring diagrams'

90sickfox

Wasn't a pretty sight...and I've got big hands

Bullitt347

I have been doing it wrong this whole time

limp

wrap a little cheese around it and its a done

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

Ybfav84

Member

DR1962

Member

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Brake issues again smh

Member

lube between the nut and the face. I know my lubes

Wasn't a pretty sight...and I've got big hands

I have been doing it wrong this whole time

wrap a little cheese around it and its a done

Stangnet Facilities Maint Tech... Er... Janitor

Member

Member

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