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firedawg77
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Okay what can cause my 73 mustang to accelerate on its own ? Drive perfect and then it feels like throttle sticks and it revs like crazy and car shoots forward few times i could put it in nuetral and back to drive it would fix it cleaned gas pedal thinking it might be dirty . Wife drove it with my duaghter and drove perfect monday i change brake pads and test drive it brakes work good take it out of neighborhood and everything works good we get about 50 yards from stoplight and it does it and quickly put it in nuetral and slam on brakes but nothing. We totaled our beautiful mustang!!  Now my wife is in hospital and i have 9 stitches in my cheek.  What happened??? Work that has been done by mechancic is ..intalled cam i believe around a 500 lift but not completely sure heads been cleaned and reworked aluminum intake 2v to 4v abd holley 750 double pump carb and headers installed. Nothing has happened like this till we took it to the mechanics ao i want to make sure they didnt do something wrong

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WOW, Glad you didn't get hurt worse. No idea on the engine rev on it's own. I could see maybe sticking when you had it pegged but acceleration on it's own???

Something has to open up the throttle plates to get the fuel air mixture needed. Very strange.

Hope you had a good insurance policy and I would dig deep might be some liability to mechanic.

If you part it out I could use the factory trailer hitch I have two 72 and they are different due to bumper move on the 73.

When a man is in the woods and talks and no women are there is he still wrong??:P

David

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oooh man that's a disaster...

Hope your wife will get better soon and that its not too bad.

 

For the weird behaviour. Unless it was EFI equipped, I can only imagine the carb linkage/ faulty pedal cable...

Looking at car damage, you should still be able to (let) inspect these.

73 modified Grande 351C. (Finally back on the road woohoo!) 

71 429CJ. ( In progress )

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Thanks she is doing good broken femur and rehab . As for parts i won't be able to part it out . Next fri i am supposed to go on active duty in texas for 2 months if it works out to where i can i will let people know . Police did say there was something wrong with the throttle cable and that is why he is saying mechanical malfunction is the cause of the wreak . I just dont understand why the brakes didn't stop the vehicle i had my foot to the floor on the brakes

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I hope you all get better soon.

 

It's a mechanical system so something was stuck.

Double pump carb means vacuum secondaries could not stick open.

Was an additional return spring installed along with the one on the carb? Was the stock return spring removed? The carb has a return spring (or should) and there should be at least one other return spring. I prefer three.

 

You will also want to take a good look at the linkage to see if it could bind on the manifold or air cleaner. Did they attach the kick down for the transmission? Did they use the kit Holley Ford kit or did they fabricate something?

 

So what happened? Did you floor it and it stuck or did the pedal seem to fall to the floor?

 

I know it won't help you but tips for others that find themselves in a similar situation.

 

- Turn off the ignition but not to the lock position, you want to be able to maintain steering control. Your brakes will loose vacuum and you may get one good assisted pump so be ready for that. Also power steering will not work, this gets more troublesome as you slow down.

- Try lifting the pedal with your foot. I have done this before shutting the car off but had plenty of room.

'Mike'

73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

 

Pics of modifications included in: [button=http://www.7173mustangs.com/thread-1973-convertible--3335]My Garage[/button]

 

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I'm so sorry to read this and I hope you and your wife will be OK again soon. This is scary stuff, I'd be interested to know the cause so that I can prevent this from happening with mine...

 

All the best!

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Wow! Scary stuff. Good to read that your wife is doing ok! The right side of the car looks really bad! Lucky that the windscreen pillar went outwards with the rest of the door ( or did the fire brigade cut it like this? ).

I wish you both a speedy recovery!

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Busted engine mounts? Had this happen to a guy I know and the engine moved upon accelaration from Start, causing the throttle cable to stick.

Thx, Alex

 

 

73 vert, 351 2v, red/white/white, RWLs on factory alloys, a/c, pwr roof, pwr steering, pwr brakes, front discs

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I honestly dont know i haven't had a chance to look at the mustang since it happened and i am supposed to go on active duty next friday . The pedal didnt get stuck and i cant remember if it fell to the floor it happened so fast i just remember it reving so loud and it taking off faster than i ever thought it could . I wish it would have happened after the stop light because would have had a long road to quickly do something. 50 or so yards isnt enough time to do crap ! We where going about 30 mph and i let off the gas and it just reved up so loud and took off i didnt floor it or anything i just did the brakes so i didnt want to test. I remember someone telling the police that they heard the mustang reving super loud so i know that actually happened .. just can't believe it happened and that fast

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It does sound like a broken motor mount, but your '73 should have the "safety" motor mounts, which keeps the mounts from pulling apart. Possibly the bolts came loose.

Or, as previously mentioned, broken or missing throttle return springs.

When your car is accelerating you have little to no vacuum to the power brake booster, especially if the check valve is bad.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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It does sound like a broken motor mount, but your '73 should have the "safety" motor mounts, which keeps the mounts from pulling apart. Possibly the bolts came loose.

Or, as previously mentioned, broken or missing throttle return springs.

When your car is accelerating you have little to no vacuum to the power brake booster, especially if the check valve is bad.

 

This is a pretty rough thread, sorry to hear it happened. What is the safest replacement motor mount setup for a 73? I never seemed to figure out the winning combo but this is a wakeup call!

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Sorry to hear about the accident. I hope you guys are doing better.

My gas pedal once got stuck but after hitting it to full throttle. The carb cam wedged the spark plug wire and kept the accelarator stuck at full. It is hard for the OEM brakes to counter all that power from thd engine.

 

Sent from my SAMSUNG-SM-G930A using Tapatalk

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1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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So sorry to read about what happened to your family and your car. I had the same thing happen to me in an old maverick of mine, in my case the throttle cable got in to a bind causing an uncontrolled full throttle situation while coming down a mountain road. Fortunately a quick restab of the throttle corrected the situation. I hope everyone comes out okay after this ordeal.

351w - Ford racing GT40X 178 cc aluminum heads - Ford racing(crane) 1.7 roller rockers - Comp Cams 280H magnum cam .544" / .544" lift - ARP hardware - hedman longtubes - magnaflow exhaust with X pipe - Duraspark - MSD digital 6al box - MSD TFI coil - optima red top battery - tuff stuff 140 amp alternator - weiand stealth intake  - edelbrock 1406 600 carb  - march pullies and brackets - Be cool fan controller - derale electric fan - FMX trans - motive 4.11 gears - traction lok - lakewood traction bars.                                            

 

 

 

 

 

 

 

 

 

 

 

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OMG, I hope they will recover soon.

I was in a Vette with a friend of mine after changing the carb to a larger one and exactly the same thing happened. It was the seal between the air cleaner and carb that sucked into the carb (we testdrove without air cleaner) and made the butterfly's stay open.

Another possibility might be the floor mat, it took me a while to find that out on my fathers 05 Stang. He also had a stuck throttle every now and then. After "fixing" the floor mat to the floor it never hapened again.

Edwin

 

71 Convertible 250-auto

71Mach1 4.6-32v/IRS project

71 Shelbyeuropa GT350-auto HO 1 of 9

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Very sorry to read about the accident. Hope the recovery from injuries goes well.

 

Was the acceleration cable stock or aftermarket? I once came upon a friend with a street rod parked along the side of the road who was very shaken up. His engine had done what you describe, but he was lucky in that he was able to pull off to the side and shut down the engine with the key. Turned out to be an incorrectly installed Lokar cable which had a swage stud located near where it passed thru the firewall by the pedal. The stud caught in the opening and pulled the carb throttle wide open.

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I have two 73 verts and three 72 but have not driven much. I just do not see a way it can do that and I  for sure want to learn from this. Unless someone changed the motor mounts as stated they should not allow the engine to rotate and cause it. The mounts are specific to the vert also for 73 I am told. I will go look at cars today and see if I can find anything possible to cause it.

Keep us informed on the progress of wife and be safe on your deploy.

When a man is in the woods and talks and no women are there is he still wrong??:P

David

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Its not the motor mounts it was fine till I had the cam and the rest of the upper part of engine done . I really feel like its carb involved.. So the reason the brakes didn't work is because it was accelerating? I really need to look at the engine but I dont have the time

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Sorry. Im Late for this.

I'm really happy that you and your family weren't hurt more than that. Especially given what the car looks like! I wish you a fast recovery.

It's sad for the car too of course.

I'd really like to learn from this because this is scary. I could imagine the throttle getting stuck after acceleration but accelerating on its own?!?! That's scary!

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Mike
"If I were you...... I´d rather be me." 😛
Check out my video:
http://www.7173mustangs.com/thread-my-mustang-in-action

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carburetor coming lose from intake manifold or a part in the carburetor self? 

no brakes or hard brakes ... vacuum leak to booster

acceleration ...very rich gas mixture with air... gas throttle cable or maybe kick-down rod attracted

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Its not the motor mounts it was fine till I had the cam and the rest of the upper part of engine done . I really feel like its carb involved.. So the reason the brakes didn't work is because it was accelerating?  I really need to look at the engine but I dont have the time

 

Dayum.....

 

Hope your wife makes a full recovery. 

 

Brakes are vacuum boosted. Hard acceleration / WOT drops vacuum down significantly. You're also fighting the engine. If it ever happens again on another car, pop it into neutral and let the engine rev.

 

 

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Puh, that sounds like a horrible nightmare... :-/ 

 

Hope your wife and you are recovering soon!

 

I am sorry for your loss...

 

But I have no idea than that what others still have said...

Tim

 

Never drive faster than your guardian angel can fly :runninpony:

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So sorry to hear this. Like the others I suspect the throttle cable stuck open for some reason, likely interference in the linkage. Brakes in proper operating condition should still stop the car under that circumstance, but pedal effort would be significant.

 

Hope you and your wife make a full recovery.

http://www.7173mustangs.com/gallery/1_01_07_15_8_53_18.png

 

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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