#1  
Old 05-29-2023, 10:37 PM
1974-trans-am 1974-trans-am is offline
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Default 1974 Trans Am 455 400 stalls out

I have an all original numbers matching 1974 Trans Am 455 (not SD) auto I bought new in September 1973. Just turned 30,000 miles and has been stored several years in heated storage. Replaced original tires, tuned it up with new plugs, points, new fluids - etc. Driving the car several miles and coming to a stop it will shut off like I was turning the key off. Doesn't do it often but always when in traffic. It than turns over fine and after several seconds will start up like nothing was wrong. Doesn't seem flooded - more like no gas. Put camera down gas tank filler and tank is clean with no rust. Fresh gas, lines all ok and fuel pump looks fine. Does anyone have a similar problem? Grounds look good, no fuel leaks, checked coil, new vacuum lines, battery cables good, - nothing obvious. My first post. Thanks for help
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  #2  
Old 05-29-2023, 11:38 PM
Schurkey Schurkey is offline
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What is the fuel pressure when the engine stalls?

Do you have STRONG spark immediately after the engine stalls, if you were to crank the engine? How do you know?

Points/condenser distributor?

  #3  
Old 05-30-2023, 02:48 AM
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It sure sounds like something fuel related.

When it dies out on you if you remove the air cleaner and look down into the carb while working the throttle can you see the accelerator pump working hood, as in with not much throttle lever movement?

When you rev it up to 4500 thru the gears how does the motor preform?

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Old 05-30-2023, 06:20 AM
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1st, Welcome to PY!



Next time it dies, take the air cleaner off and look in carb. Move throttle arm and see if any gas squirts out. If not, then crank it for a couple seconds and re-check to see if gas squirts out then.

Make sure choke is open, filter isn't clogged, no obvious loose wires on distributor/coil.

If gas ruled out, then will need more intensive sleuthing.


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Old 05-30-2023, 11:56 AM
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Wow - what a time capsule...

Have you ever upgraded your cap & wires?

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'74 T/A 455 Y-code SD clone

previously on Dawson's Creek:

'74 T/A 400
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  #6  
Old 05-30-2023, 12:49 PM
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77 TRASHCAN 77 TRASHCAN is offline
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Welcome to the original TA owners club (LOL)!!!

Has the carb ever been off the engine???
I'm wondering how well the base gasket is sealing, if original...just a thought...

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  #7  
Old 05-30-2023, 03:59 PM
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For the record, I don't know anything. But, if it's cutting out at low RPM and low load, and then it's instantly fine again, that doesn't really seem like a fuel delivery problem. Sounds more electrical. What happens at WOT?

Also, that is soooo cool that you are the original owner of a low miles survivor. Very, very cool indeed. That's special.

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Old 06-01-2023, 08:27 PM
1974-trans-am 1974-trans-am is offline
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Thanks for all the replies - lots of good ideas. I was a mechanic back in the seventies and eighties but have been away several years now. When I bought this car new I really wanted an SD but it was a daily driver the first few years except in the winter. The SD would have been out of its element. I have since bought a one owner original paint SD and in the process of cleaning and preserving it. Glad I found this forum

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Old 06-01-2023, 09:28 PM
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Pics are always welcome!



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  #10  
Old 06-02-2023, 04:34 PM
1974-trans-am 1974-trans-am is offline
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Quote:
Originally Posted by johnta1 View Post
Pics are always welcome!


Here's a link to the SD that was featured in Bring A Trailer in January, 2021
and not sold there. I bought it in July 2022 from the owner. It has surface rust on the underbody
but in far better condition than it looked on Bring A Trailer. The SD and Blue 455
I have go well together. I'm in the hunt for a low mile original 1974 Trans Am 400
4 speed white car to have the 1974 engine and paint line up. https://bringatrailer.com/listing/19...55-super-duty/


Last edited by 1974-trans-am; 06-02-2023 at 04:45 PM.
  #11  
Old 06-02-2023, 04:41 PM
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Could it be bad gas, from sitting over winter? Fresh full tank ought remove all doubt.

If you have a Tach, watch it for tell-tale loss of spark.

  #12  
Old 06-02-2023, 05:35 PM
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Oh wow, nice SD.

Trifecta hey...super! 😎

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'74 T/A 455 Y-code SD clone

previously on Dawson's Creek:

'74 T/A 400
'81 AMC SX/4
'69 FB 350
  #13  
Old 06-02-2023, 06:45 PM
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Thinking outside of the box if the other suggestions don’t work, first, what about the seatbelt interlock? I know they’re designed not to stall the engine if a belt is unbuckled for example but what if it’s malfunctioning. Could that cause the symptoms seen? I know little about their function so I may be way off.

Also, does the engine die alone or does all power seem to die (radio, gauges, etc).

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  #14  
Old 06-03-2023, 06:00 AM
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A fast cheap and easy way to confirm by yourself if it’s fuel related or not is to spray some starting fluid into the carb when it has died.

If it kicks well or starts for a second then you have spark but no fuel.

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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs!
And he was not talking about 1/8 or 1/4 mile ETs!

1) 1940s 100% silver 4 cup tea server set.

Two dry rotted 14 x 10 Micky Thompson slicks.

1) un-mailed in gift coupon from a 1972 box of corn flakes.
Two pairs of brown leather flip flops, never seen more then 2 mph.

Education is what your left with once you forget things!
  #15  
Old 06-05-2023, 08:43 PM
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That has happened to me before and it was the sock filter in the tank. I also had the convertor lock up on me, will it stall up at all when you foot brake it? That also happen to me when it had a vacuum lea at the brake booster..

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