Hard accelerator pedal
May 1st, 2019, 04:16 AM
#2
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Make sure the accelerator cable isn't binding between the carb and pedal. If the cable isn't kinked then make sure the carburetor throttle moves freely. You might just have a throttle return spring that's too big on the carb.
May 1st, 2019, 05:30 PM
#9
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May 2nd, 2019, 02:39 PM
#11
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Frayed throttle cable, or seizing throttle-body bushings would be the most likely, but any worn or dry pivot point in the linkage could be part of the stiffness. As said, sometimes a swollen or "flipped" accelerator pump cup can bind in the pump bore.
May 2nd, 2019, 07:33 PM
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Nope. Read about it years and years ago. I'm sure it's a safety regulation--having a redundant spring in case one would fatigue and break.
But it's no coincidence that if you search for "throttle spring" on the Summit site, virtually every product is a dual-spring system.
https://www.summitracing.com/search?...ottle%20spring
But it's no coincidence that if you search for "throttle spring" on the Summit site, virtually every product is a dual-spring system.
https://www.summitracing.com/search?...ottle%20spring
May 2nd, 2019, 08:07 PM
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https://www.federalregister.gov/docu...ontrol-systems
The purpose of Standard No. 124, Accelerator Control Systems, 49 CFR 571.124, is to reduce deaths and injuries resulting from failures of a vehicle's accelerator control system. Since 1972, Standard No. 124 has specified requirements for ensuring the return of a vehicle's throttle to the idle position...
Standard No. 124 at S5.1 requires that each vehicle have “at least two sources of energy,” each independently capable of returning the throttle to the idle position, within the time specified in paragraph S5.3, from any accelerator position or speed whenever the driver removes the actuating force. The Standard defines the throttle as “the component of the fuel metering device that connects to the driver-operated accelerator control system and that by input from the driver-operated accelerator control system controls engine speed.”
The two energy sources were simply two return springs acting on the linkage between the accelerator pedal and the throttle. If at least one of those springs ... were connected directly to the carburetor or to the diesel fuel injection rack, it would cause the throttle to return to idle in the event of a disconnection of the pedal linkage. If the disconnection occurred at one of the springs, the other would permit continued driver control.
Given that the original poster is discussing a 1972 vehicle, his car is required to have two springs.
Last edited by Schurkey; May 2nd, 2019 at 08:10 PM.
Hard accelerator w
May 3rd, 2019, 12:41 PM
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It's all there in posts 1 and 9, although there's some good advice in between, and after those posts.
The OP thinks he's solved a problem by removing a second throttle return spring, and he hasn't. He's just covered-up the symptoms of some other problem.
The car is SUPPOSED to have two springs, Two springs doesn't make the throttle stiff. They ALL had two springs by law starting in '72. So, aside from assuring that he's got the proper two springs, he needs to be looking somewhere else for the source of the throttle-motion problem.
As I've said before--any pivot in the linkage, a frayed throttle cable, worn throttle body bushing or throttle shaft, and, I suppose, stiff, hardened grease in a TH400 kickdown switch could be potential causes. Some are more-likely than others.
Thanks for being obstinate and making me look up the Federal regulation. Until I saw the regulation, I thought the dual-springs were required in '68, perhaps before.
The OP thinks he's solved a problem by removing a second throttle return spring, and he hasn't. He's just covered-up the symptoms of some other problem.
The car is SUPPOSED to have two springs, Two springs doesn't make the throttle stiff. They ALL had two springs by law starting in '72. So, aside from assuring that he's got the proper two springs, he needs to be looking somewhere else for the source of the throttle-motion problem.
As I've said before--any pivot in the linkage, a frayed throttle cable, worn throttle body bushing or throttle shaft, and, I suppose, stiff, hardened grease in a TH400 kickdown switch could be potential causes. Some are more-likely than others.
Thanks for being obstinate and making me look up the Federal regulation. Until I saw the regulation, I thought the dual-springs were required in '68, perhaps before.
Last edited by Schurkey; May 3rd, 2019 at 12:45 PM.
May 3rd, 2019, 01:15 PM
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May 3rd, 2019, 04:58 PM
#22
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I second the frayed cable. Before I got my first Cutlass at 16, I drove the fambly Ford station wagon. Once I took it to the grocery store, about 3 miles and six controlled intersections away. Before I got to the store I realized the engine was running FAST and I was not on the accelerator. I tapped the pedal a couple times, thinking "the choke is stuck, and I'll bump it loose." You guessed it, the engine revved higher. Being the mostly dumb 16 YO driver, I drove the thing back home 
where I told my dad about it. This was in fall of '78 - no cell phones. Dad came out to check it out and we found the accelerator cable massively frayed where it went through the firewall. The grommet was still serviceable and doing it's job.
where I told my dad about it. This was in fall of '78 - no cell phones. Dad came out to check it out and we found the accelerator cable massively frayed where it went through the firewall. The grommet was still serviceable and doing it's job.
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