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Author Topic: Truck starts but dies when I give it gas  (Read 2481 times)

Offline 78Hawk

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Truck starts but dies when I give it gas
« on: December 01, 2017, 07:54:01 AM »
Hello All,

I’ve finally got the 78 C10 to start but idles ruff and when I give it gas it dies. Sometimes it will continue to run but not consistently. I’ve changed the fuel tank and pick up, coil, battery, distributor, ignition switch a the base of the steering column and had the carburetor rebuilt.  What is the deal? The truck has a 454, Edelbrock intake and a Holley 4 barrel.
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Offline zieg85

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Re: Truck starts but dies when I give it gas
« Reply #1 on: December 01, 2017, 10:34:25 AM »
The choke may be opening to soon would be my guess
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1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
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Offline Irish_Alley

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Re: Truck starts but dies when I give it gas
« Reply #2 on: December 01, 2017, 11:19:01 AM »
improper tune maybe? check for a vacuum leak and go from there.
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Offline VileZambonie

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Re: Truck starts but dies when I give it gas
« Reply #3 on: December 01, 2017, 11:20:07 AM »
You need to check the accelerator pump discharge
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Offline Henry

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Re: Truck starts but dies when I give it gas
« Reply #4 on: December 01, 2017, 12:14:05 PM »
Hi 78 Hawk:
Sure sounds like carb problems. But, with all those replaced parts, have you verified the timing, dist advance features, initial idle mixture screw settings, and choke settings?
Regards,
Henry
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Offline blazer74

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Re: Truck starts but dies when I give it gas
« Reply #5 on: December 01, 2017, 04:56:27 PM »
 More info: Runs warm? Electric choke? Has it backfired thru the carb? Fuel filter and lines replaced with the tank?
Make sure there’s no open vacuum ports anywhere on the carb or manifold.
PVC hooked up and where?
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Offline 78Hawk

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Re: Truck starts but dies when I give it gas
« Reply #6 on: December 01, 2017, 10:54:01 PM »
Yes it runs warm, electronic choke. Yes it back fired and actually shot fire from the carb.
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Offline blazer74

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Re: Truck starts but dies when I give it gas
« Reply #7 on: December 01, 2017, 11:36:50 PM »
Holley’s are known for blowing power valves with intake backfires causing over rich idle mixtures causing rough idling.

Intake backfiring can be from incorrect timing, crossed up firing order, lean fuel mixture, vacuum leaks and also valve train problems.

Choke should open 1/8 to 3/16 when engine starts. A little either way makes a big difference in a cold engine.

Mileage on engine?
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