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12-27-2023, 07:32 PM
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#1 |
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Registered User
Join Date: Oct 2020
Location: ca
Posts: 106
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Truck stumbles when cold
I recently changed my oil when the problem started IÂ’m donÂ’t know if itÂ’s related or not. We are having a cold streak here itÂ’s in the 60s. When I drive the truck it feels like it stumbles. It never actually stalls it just feels like itÂ’s going to and the power drops out. The truck seems to start normal it does seem to idle weird at stoplights. Is this something to do with the cold or my oil change?
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12-27-2023, 07:58 PM
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#2 |
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Registered User
Join Date: Dec 2017
Location: Elkhart, Texas
Posts: 1,853
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Re: Truck stumbles when cold
I don't see how a simple oil change can cause engine stumble, so I'm going with ambient temperature.. Check choke operation and fast idle setting. Also TCAC operation is critical in cold weather.. Posting the checking and testing procedures are a lengthy writeup. Refer to the Factory Service manual for these items..
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12-27-2023, 08:04 PM
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#3 |
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Registered User
Join Date: Dec 2005
Location: Kalifornia
Posts: 354
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Re: Truck stumbles when cold
60 isn't cold. Check your idle mixture.
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12-27-2023, 08:09 PM
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#4 |
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Senior Member
 
Join Date: Apr 2016
Location: Cypress, TX
Posts: 3,884
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Re: Truck stumbles when cold
I was having my truck stumble and often stall upon startup when it's colder, and I adjusted the choke to have a slightly more open choke plate when cold, and that resolved it for me.
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12-28-2023, 11:37 AM
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#5 |
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Registered User
Join Date: Apr 2022
Location: Medina, Ohio
Posts: 227
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Re: Truck stumbles when cold
Vacuum leak, hose line, might have got bumped when you were adding oil, air cleaner moved, ect. Spray carb cleaner around intake, careful, focused area.
What vehicle do you have. Eng, trans. Last edited by 1967GMCC20; 12-28-2023 at 12:45 PM. |
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12-28-2023, 12:27 PM
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#6 |
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Registered User
Join Date: Dec 2023
Location: Pensacola, FL
Posts: 41
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Re: Truck stumbles when cold
Is it stumbling all the time, intermittently, or just on acceleration?
Timing issue? Mine stumbles on acceleration if I don't have the timing advanced a little bit from spec. I haven't chased down the reason why yet (it's gotta be either the vacuum or mechanical advance is lazy, I guess), but it runs ok if I put the timing at +13 or so. A $15 vacuum gauge/fuel pump tester combo from Harbor Freight would let identify or rule out vacuum leak and bad fuel pump. Plus there are wise men on this forum who can tell you all about reading the tea leaves of vacuum gauge behavior to diagnose other issues. |
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12-28-2023, 03:13 PM
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#7 |
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Registered User
Join Date: Oct 2020
Location: ca
Posts: 106
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Re: Truck stumbles when cold
Thanks I’ll take a look at the idle and choke this weekend.
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12-28-2023, 07:54 PM
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#8 |
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Who Changed This?
Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,723
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Re: Truck stumbles when cold
Here is a vacuum chart to use.
__________________
~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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12-29-2023, 02:05 AM
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#9 |
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Registered User
Join Date: Jun 2010
Location: San Diego Co.
Posts: 1,179
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Re: Truck stumbles when cold
Nice vacuum legend there. Thanks for posting.
__________________
1972 Chevy C-10, SWB, Fleet, 350/350, PS, PB, HEI, mostly stock, Survivor. 
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12-29-2023, 11:53 AM
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#10 |
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Who Changed This?
Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,723
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Re: Truck stumbles when cold
Thanks! The header in the pic shows I got it here, so thanks to whomever posted it before, too.
__________________
~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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12-31-2023, 10:05 PM
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#11 |
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Registered User
Join Date: Oct 2020
Location: ca
Posts: 106
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Re: Truck stumbles when cold
Do I use that chart with the engine at idle or when I give it throtle? Or both?
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