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Topic: 74 Corvette Engine Cut out on Freeway

in Forum: C3 Electrical

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74 Corvette Engine Cut out on Freeway (1/11)
8/10/12 11:44am

Cruzrkid
Former Member
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Auburn, CA - USA

Vette(s):
1974 C3 Corvette Stingray T-Top 4 Speed, High Output, Manual Windows

Joined: 3/28/2012
Posts: 5

Hi Everyone,

I have a quick question: My 1974 Corvette cuts out on the freeway when I put the engine under load. The problem DOES NOT appear to be fuel related (But it could still be the problem). It feels as if someone just disconnected the battery for a second. The car does not sputter, it just stops running for a second and then runs again. I have rebuilt the carburator with no change in the issue. I have replaced the cap, rotor and coil on the car as well as timed the car. Although this made the car seem to run better, it did not stop the problem. I have not replaced the wires or the plugs. If the car is just idiling or at low RPM's it runs fine with no issues. It's only when I put my foot on the gas and rev the engine under load that it seems to have this problem. Any ideas? I wanna drive my car! :)

Thanks!

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Re: 74 Corvette Engine Cut out on Freeway (2/11)
8/10/12 12:26pm

ebo

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Holland Patent, NY - USA

Vette(s):
#1 *1980 White, Red interior 14,000 mile #2 *1980 Red, Oyster interior 93,000 miles Resto project car, rebuilt to 383 stroker

Joined: 6/3/2008
Posts: 4421

Brian, still sounds like fuel to me, can you get a fuel pressure gauge in line and watch the reading when working the throtle. I'm sure you changed the in line carb filter right?

Then it's fuel pump......or dropping the tank and changing the sock on the pick up.... Shocked

Good luck, keep us informed.

ebo

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ebo

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Re: 74 Corvette Engine Cut out on Freeway (3/11)
8/10/12 1:14pm

Adams' Apple

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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

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Cruzrkid said:

It feels as if someone just disconnected the battery for a second. The car does not sputter, it just stops running for a second and then runs again.

The description sounds more like an electrical issue. Have you noticed if any of the gauges blip/flake out when this happens? A fuel problem would not cause all 8 cylinders to just stop firing at the same time...but an electrical, or ignition problem would.
As a test, you could run a "hot wire" from the battery to the ignition coil, and drive it to see if it still cuts out.
Make sure your battery connections are good, and don't forget the grounds.

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Re: 74 Corvette Engine Cut out on Freeway (4/11)
8/10/12 1:24pm

Cruzrkid
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Auburn, CA - USA

Vette(s):
1974 C3 Corvette Stingray T-Top 4 Speed, High Output, Manual Windows

Joined: 3/28/2012
Posts: 5

Hey thanks guys. That's exactly it, all 8 cylindars stop firing at the same time. It's like someone pushed the kill switch! :) I'll try the suggestions you came up with. Is there a regulator or any other substantial electrical components that could be causing this?

The weird thing about it is that it only seems to do it when I put a load on the engine. I'll try the suggestions.

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Re: 74 Corvette Engine Cut out on Freeway (5/11)
8/10/12 1:32pm

Adams' Apple

Under a load, the engine could be shifting enough to break a connection somewhere, or the accelerator cable could be flexing enough to move the coil wires, or something equally silly. Could also be some wires under the dash that are getting moved when you get on it.
If you keep you foot in it when it does this, does it completely die, or does it still just on/off quickly?
Does it ONLY do it when you go full throttle, or anytime you give it just a little more throttle?
An accelerator pump that is not responding properly could cause a hiccup/burp like this, but it would do it every time you give it gas...not only while cruising under a load.
I think it's electrical at this point.

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Re: 74 Corvette Engine Cut out on Freeway (6/11)
8/10/12 5:40pm

dskopp
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Oak Creek, WI - USA

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1981 Great White Shark. Red Interior, 350/190hp. PS, PB (SS), A/C CC, T-Tops, Going to remain as Stock as possible. Served three years in Active Duty Army, then Retired Air Force after 34 years! Badger State Vetts Car Club. 175,000 Original miles!!

Joined: 5/21/2008
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My money is riding on a wire type problem!! Short and Sweet!!

Dan

P.S. Does everybody like the "In-Bred" Cat!!!

|UPDATED|8/10/2012 2:40:20 PM (AZT)|/UPDATED|

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Re: 74 Corvette Engine Cut out on Freeway (7/11)
8/11/12 11:44am

tonytheroofer
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Rochester, NY - USA

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1980 L- 82 fully restored and upgraded.

Joined: 6/12/2012
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Get under car by starter and make sure the hot wire is not contacting the exhaust or engine block when you load the motor. Also if thats all good have someone sit in car with foot on break put it in reverse and load motor see if it cuts out that way also try drive the same way. I one time did this in the dark to find a dead short under load , I was able to see the spark that way lol..

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Re: 74 Corvette Engine Cut out on Freeway (8/11)
8/12/12 3:21pm

aceinthehole

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Manteca, CA - USA

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1978,two tone,Metalic Rootbeer & gold 1975 L48 4 speed

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Hi Brian, If you haven't checked them yet, it's always a good idea to at least inspect, if not replace the rubber fuel lines starting at the tank just under the rubber boot around the fuel cap and follow them forward to the fuel pump to eliminate any trouble now and later. The lines before the pump can suck air through cracks sometimes without the telltale signs of spewing fuel. Every old Vette should have those checked out asap when you bring one home, it's not hard.

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Jimmy B.
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Re: 74 Corvette Engine Cut out on Freeway (9/11)
8/17/12 12:15pm

blacksharkL82
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spring hill, FL - USA

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92 coupe, full minor custom, in & out

Joined: 5/18/2002
Posts: 33

I had that same probl;em with my 69 vette and my 81 truck.

The trucks problem was the fuel filter.

The vettes problem was the wire harness connector at the firewall on the engine side.

Both acted the same way.

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michael Black Sheep Squadron |URL|http://www.rogerscorvette.com/free/lintini.htm|/URL| |URL|http://www.cruisercustomizing.com/blackvette|/URL|

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Re: 74 Corvette Engine Cut out on Freeway (10/11)
8/17/12 12:22pm

Adams' Apple

blacksharkL82 said:The vettes problem was the wire harness connector at the firewall on the engine side.

That's a dang good idea, too..... Thumbs Up

The firewall pass-thru on these things can get corroded, and cause all kinds of weird and unjujual problems. Sometimes just the flexing of the body over bumps can cause it to loose contact of r a second...

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Re: 74 Corvette Engine Cut out on Freeway (11/11)
8/17/12 12:26pm

Cruzrkid
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Auburn, CA - USA

Vette(s):
1974 C3 Corvette Stingray T-Top 4 Speed, High Output, Manual Windows

Joined: 3/28/2012
Posts: 5

Hey Thanks guys! I'll try checking that all out this weekend. I really appreciate everyones ideas!

thanks! :) Hug

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