nutz4hs

okay, im new here and i know theres probably a rule about using search before posting, just to let you know i did and there was a similar post but it didnt go in dept enough.

ive spent a bit of time searching for an answer for this question and im hoping that bouncing the ideas off people that may have experience will help.

i have a 67 mustang coupe, with 50k miles on the engine/trans.
its a 289 with an auto that hasnt been rebuilt. it ran fine till a month ago when it started struggling in gear, it will idle and run fine in park and neutral, but in gear, it will idle horribly, and even stall. once moving it will once again run fine, but if you are in gear and use the brake, it will attempt to stall, then will hiccup, (the brake pressure will drop a bit, causing the car to roll foward a tiny bit, then will catch again and the engine will compesate, this happens every time the brakes are used. so any suggestions? id greatly appreciate any help

FuglyStick

How does it take throttle when it's not in gear? If it is still revving all right, you can probably eliminate a fuel problem.

You may want to check the timing. Sometimes an engine will run fine without a load, but will act up under load if the timing is out of whack, causing a dip in horsepower; if it's enough out of whack, it can cause stalling.

It could also be a brake problem. If the emergency brake cable is adjusted too short, the shoes will drag in the drum (I'm assuming you have rear drums), and when you have it in gear attempting to move, the engine has to compensate for the extra drag, causing it to stall under low rpms. Then again, one of the springs that hold the shoes around the spindle could be stretched or broken, causing the shoe to ride the inside of the drum when the brakes are not engaged as well. (That should only happen in one direction though; do you have the same problem in reverse?)

If the problem was with the transmission or the rear axle, I would suspect you would have some noise to go along with your stalling problem.

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nutz4hs

it will rev fine and seems to run quite happily as long as its not in gear. it will handle acceleration fine until the time you hit the brakes.

it does this in both reverse and drive, whenever the tranny is locked in to place. this only happens when coming to a complete stop, you can slow down to about 5-10 mph before this starts
the E-brake cable is non existent on this car, its heater core leaked while it was in storage and rotted the floors to nothing, so when the floors fell through, so did the support to the brake cable, (it on my huge list of things to fix) the brake light is on, in the dash, the previous owner was a mechanic and swapped all the brake lines and fittings, and rebuilt the brake housings. so im thinking its simply linked to the proportional valve being uncentered, the rear wheels will lockup well before the front stops rolling. when this last ran it was very warm, around 80 degrees, this started when it started to get colder, do i have to adjust the carb for weather differences?



also when it does stall, it doesnt just labor like stalling a standard trans, it kinda struggles and will drop rpms slowly, then sound out of tune when the rpms are about to drop. but theres no noise from the trans or the rear, it just simply quits. even when its really close to stalling, its usually able to stay running if i let off the brake or kick the gas a smidge,

thanks for your thoughts, i really appreciate the help, im not a gearhead, mostly a tinkerer, i got the car for around 2000$ in running shape, with alot of new mechanics already on the car.

kinsaj

Sounds like ignition or fuel. First make sure the timing is right and that you are getting a good spark. If not that then start playing with the carb. You do not need to adjust for temp change but you do for significant elevation change. Also make sure your fuel filter is not clogged.

Does the car run different when the engine is cold vs warmed up?

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cj2112

Give the car a good tune-up. Points, plugs, plug wires, cap and rotor. Check ignition timing and dwell.

If the above doesn't solve it look for leaking vacuum lines.

Was their old fuel left in the carburetor when the car was stored? Did it build up varnish in the carburetor?

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"If gun laws in fact worked, the sponsors of this type of legislation should have no difficulty drawing upon long lists of examples of crime rates reduced by such legislation. That they cannot do so after a century and a half of trying--that they must sweep under the rug the southern attempts at gun control in the 1870-1910 period, the northeastern attempts in the 1920-1939 period, the attempts at both Federal and State levels in 1965-1976--establishes the repeated, complete and inevitable failure of gun laws to control serious crime." Senator Orrin Hatch, Chairman, Senate Judiciary Committee Subcommittee on the Constitution, 97th Cong., 2d Sess., The Right to Keep and Bear Arms, Committee Print I-IX, 1-23 (1982).

nutz4hs

ill have to check for the timing, it could be a issue. as long as its reasonable that the timing would change that much over a few month to go from running great to stalling,

@cj2112, the carb was one of the items that was cleaned and tuned heavily, around 2-3 months ago so i dont think thats an issue, the plugs wires, rotor and cap look brand new. also can vacuum cause this much problems? i know for a fact that a few vac lines are missing, (ac unit, heater, and dash stuff,) the lines just dryrotted apart.

@kinsaj, ive thought about the fuel filter, but cant seem to find one on the car, any idea where it should be? the last owner did replace alot of the fuel lines and added a brand new tank,pump and filler hose, ive traced the fuel lines all the way back to the tank and havent seen one, last i can think is tank mounted?

thanks for the replies.

cj2112

So we've likely ruled out the carb, rotor and plug wires. The cap could have a hairline crack, but for now let's assume it's good. The timing could have changed that much if the distributor moved. I'd also check the dwell, and the condition of the points as well as the condition of the cam that operates them.

It is unlikely that the fuel filter is tank mounted. It is typically an inline filter found on the supply line for the carburetor. No telling what the previous owner has done though.

Vacuum may cause this, I am unsure if the advance on your distributor is mechanical or vacuum operated, if it is vacuum operated then vacuum problems might cause this.

__________________
"If gun laws in fact worked, the sponsors of this type of legislation should have no difficulty drawing upon long lists of examples of crime rates reduced by such legislation. That they cannot do so after a century and a half of trying--that they must sweep under the rug the southern attempts at gun control in the 1870-1910 period, the northeastern attempts in the 1920-1939 period, the attempts at both Federal and State levels in 1965-1976--establishes the repeated, complete and inevitable failure of gun laws to control serious crime." Senator Orrin Hatch, Chairman, Senate Judiciary Committee Subcommittee on the Constitution, 97th Cong., 2d Sess., The Right to Keep and Bear Arms, Committee Print I-IX, 1-23 (1982).

kinsaj

sounds like timing or vacuum... and I do not have much experience with either as I deal primarily with diesels and bikes. A place to start would be to hook up a mightyvac up to the vacuum line and see if it holds vacuum, if not diagnose and repair leaks.

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grumpyolddude

If the car has the Autolite/Motorcraft 2 barrel, the fuel filter should be threaded into the carb. Wix #33046.


The loss of performance when applying the brakes, assuming power brakes, points to a bad diaphragm in the booster, a leaking brake booster check valve, or damaged vacuum lines.

You should hunt down the vacuum sources for all of those missing, disconnected or dry-rotted vacuum lines and make sure they are all reattached or plugged off. Vacuum leaks = lean condition, at the very least. If you aren't getting consistent vacuum to the distributor advance (it is vacuum controlled, if still original), the brake booster and the transmission modulator, you won't run smoothly, stop reliably or shift at the proper speeds.

When you think you have all of those handled, get yourself a decent vacuum gauge. At a source off the base of the carb, you should get very close to 22 inches of vacuum at idle.

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nutz4hs

thank you for the pic of the filter, when i get a chance i will see if its there, seems perfectly logical. the carb is the 2 barrel with the 289 engine. but i do not have power brakes, which is what confused me, what would manual brakes have to do with the engine stalling?. im going to swap most of the lines out since almost everyone i look at is in terrible condition and retest the engine. will keep it posted. thanks to all for the info so far

grumpyolddude

I'll ask a couple of seasoned professionals for their thoughts on this. From your description of the symptoms, I was surprised to find out that you had manual brakes.

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"Regret can be a harder pill to swallow than failure .With failure you at least know you gave it a chance..." David Howard