'82 Chevy Pickup Hesitation when cold

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  #1  
Old 04-23-03, 12:26 PM
RMX
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'82 Chevy Pickup Hesitation when cold

This is an update of a post from awhile back.
'82 Chevy Pickup Hesitation when cold
I "acquired" an old 1982 Chevy C-10 Silverado pickup. I am restoring. 305, V-8, 102k miles. 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. 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 badly. Not drivable for 2 or 3 min. Under heavy acceleration will completely stall. After warm (about 8 min) it runs much better, although it still has 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 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.
UPDATE: I had the carb rebuilt, timing set, and plugs replaced (a couple had residue and look to be close to fouled). Now it runs better and will not completely stall, however there is still moderate hesitation when cold. Can't pull a hill or out in traffic before about 2 min of warming. It did pass emissions test fine. I'm running out of things to change or adjust. Is it running too rich ? Fuel pump ? Any Ideas ?
 
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  #2  
Old 04-23-03, 12:31 PM
Joe_F
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Could be a poorly rebuilt carburetor, but I suggest you bring it back to the person that did the rebuild and let it sit with them overnight so they can duplicate the problem.

At 102k, the timing chain probably has a good amount of stretch in it and should be replaced (the original nylon timing gears are junk), but that is not likely to be the problem here.

If it's strictly cold start/warm up related, I'll look at the carburetor choke controls again for starters.
 
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Old 04-23-03, 04:26 PM
formula_v8
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I've seen this problem before, i presume the carb is original rochester? when these carbs sit for prolonged periods of time the rebuilds are on;y as good as the carb is, things swell and constrict with weather changes so much that it becomes almost warped in places. but short of buying new carb. i'd try replacing module and condenser with new springs and weights in the distributor...chances are this stuff has corrosion on it from sitting so long and it might be hindering the timing and spark abilities enough at cold idle where you have power loss.
 
  #4  
Old 04-23-03, 05:02 PM
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Location: Canton Ohio
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They may have rebuilt the carb and not replaced the choke pull-off. The pull-off does generally come in the rebuild kits. It is the part on the carb by the choke plate with a vaccuum line attached to it. If it sat for four years the diaphram in the pull-off may have gone bad.
 
  #5  
Old 04-23-03, 05:15 PM
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Had the same problem for nearly a year and it drove me absolutely crazy, this only happened in the cold. I finally found the problem and it was a fuel line that was clogged with almost something like crude oil. In the warm it would run and start fine but when it was cold the gunk congealed and restricted the fuel line to the point where it would be hard starting the first thing in the morning and would have a slight hesitation. Look for any fuel lines that have a 180 degree bend, stuff may have settled. Good luck
 
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Old 04-23-03, 06:02 PM
Joe_F
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The pull off is a separate item. Carburetor kits only include the gaskets and needle and seat on most Rochesters.

The float, choke pull off(s) and choke stats are all separate items on Rochesters (and most others).
 
  #7  
Old 04-23-03, 06:05 PM
Join Date: Nov 2002
Location: Canton Ohio
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My bad, I meant to type "does not " and left out the "not".
 
  #8  
Old 04-23-03, 11:22 PM
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Check your centrifugal flyweights in the distributor as well as the other things mentioned. Make sure they operate freely without binding or sticking.
 
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Old 04-24-03, 06:19 AM
RMX
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Thanks Guys, you all have given me some very good ideas. I'm going to figure this out one way or another. This site is great. I always recommend it to others.
 
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Old 04-24-03, 07:08 AM
Joe_F
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Cheese has another good point.
 
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