'82 Chevy Pickup Hesitation when cold

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Old 10-16-02, 07:49 AM
RMX
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'82 Chevy Pickup Hesitation when cold

I "acquired" an old 1982 Chevy C-10 Silverado pickup. I am restoring. It had been sitting for over 4 years. When I first got it, I had to clear the wasp nest and cobwebs to see what I had. It ran, but very rough. I've been working on it for 8 months. This is what I have done so far as engine work goes:
New battery, Engine degreasing, Carb and linkage 'spray' cleaned (gumout), changed oil, spark plugs, some bad vacuum hoses, radiator, thermostat, hoses, fuel filter, air filter, water temp sending unit, manifold heat riser tube. All this got it running fairly well, except for hesitation/stall when accelerating after cold start. Will start and idle great when cold. Choke seems good, however under moderate acceleration will hesitate. Under heavy acceleration will completely stall. After warm (about 8 min) it runs much better, although it still has a very small amount of hesitation from a stand still. At speed, it has great power and cruises smooth. I have check the plug wires (saw no arching at night), checked most vacuum hoses, had a bad EFE sensor (EFE value at manifold/exhaust wasn't working, replaced that, checked the EGR valve and replaced its sensor (was cracked), checked the manifold heat riser door in the air filter housing. It's working the way it should. It is obvious it is thermo related. Other than more in-depth carb/choke work I'm out of ideas. Right now I'm driving it everyday while I'm looking for a commuter car. Any help would be great Thanks.
 
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Old 10-16-02, 10:01 AM
Joe_F
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Sounds like an old and tired carburetor. Time for a rebuild...

Disassemble it, clean it completely and replace all gaskets and parts contained in the carburetor kit (which will also have instructions), choke pull off, choke thermostat and float.

Bring the # stamped on the side of the carb (starts with 170 or 7 in most cases) with you to the parts store to find the proper replacement parts.

Don't cheap out on it. Pitch the plug wires and all expendables throughout the truck. Things rot and turn to dust when a vehicle sits that long.

I would also suggest you get the tank boiled out too. If fuel sat in there for four years, it will turn to varnish/gum and wipe things out in a heartbeat .
 
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Old 10-16-02, 02:01 PM
davidf
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cold

adjust vacuum break on carb.IE choke plate opening gap on startup of engine when ambient temperature is cold.
 
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Old 10-16-02, 03:01 PM
Joe_F
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If fuel sat in the carburetor for 4 years before it ran again, the seals in the carburetor and the gaskets are wiped out and dried out.

The needle and seat is also likely varnished with stale fuel too .
 
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Old 10-16-02, 07:54 PM
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I agree with Joe...After sitting with old fuel in the carb 4 years, the carb needs some TLC. It sounds to me like the accellerator pump is dried out and not working. Replacement of this is part of a carb rebuild.
 
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Old 10-17-02, 01:21 PM
redneck
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Joe hit it on the head--I just went through this with my '77 Formula--34,000 miles but had been sitting since '84. Car ran great when hot--started and idled great when cold or hot. But, when cold would hesitat "flat spot". Rebuilt carb with NAPA kit and it runs great! o'course I "tuned" it alittle while apart--prob. would'nt pass an emission test now--but runs much better--these cars are very lean from factory--due to primative emission controls back then they had to rely on "lean" carbs. Todays cars can actually run much richer. Due to computers.
 
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Old 10-21-02, 06:05 AM
RMX
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Thanks guys,
I'll do a carb rebuild when I can take her out of commission for a while and will let ya know how it goes.
 
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