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Carburetor Question?Fuel? #5319470 01/11/20 09:36 AM
Joined: Feb 2014
Posts: 3,607
Marco620 Offline OP
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My neighbor has a older 80's GMC Pickup and it sounds and runs awful cold or during winter. His income is limited right now so I have taken to the BITOG way and tried to help. I've let him use the last couple ounces of Redline Si-1 occasionally to try to clean his fuel system up. Would non ethanol fuel be something that could help? I cant help but to think it would. I'm contemplating giving him this can of CRC GDi throttle cleaner to help. Any insight,guesswork is great.


15' Civic 1.8 i-vtec 302,000 mi M1 AP 0w20 & LG Biotech, BP CVT Fluid,GUMOUT W/ PEA
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Doberman,Heckler & Koch & SONY Aficionado

Re: Carburetor Question?Fuel? [Re: Marco620] #5319479 01/11/20 09:43 AM
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mk378 Online Content
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Is it really carburetor? The later 80s ones have fuel injection and a computer. It's a very rudimentary system but if it is that type, see if the check engine light is on and check for trouble codes.

The last of the carburetor systems from the mid 80's, which pulled out all the stops with some crazy stuff for emission control, can be very difficult to keep running properly. Things to do here are (a) be glad it still runs at all and (b) be glad it's not your truck. Seriously, don't get involved.

Mechanic in a bottle isn't going to help here.

Last edited by mk378; 01/11/20 09:48 AM.
Re: Carburetor Question?Fuel? [Re: Marco620] #5319492 01/11/20 09:53 AM
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Chris142 Offline
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Rebuild the carb after looking for vacuum leaks.


02 Wrangler Napa high milage 10w40
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Re: Carburetor Question?Fuel? [Re: Marco620] #5319511 01/11/20 10:01 AM
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jhs914 Offline
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Check the operation of the choke if it is a true carburetor and not a throttle body injection. All of the old carb engines I've owned had an adjustment to close the choke to richen the mixture for cold starts and increase the rpm, then a pull off to reduce rpm's and open the choke when the engine warms up. Most of the time I had to blip the throttle after it warmed up to get the pull off to drop the rpm's.

Re: Carburetor Question?Fuel? [Re: Marco620] #5319527 01/11/20 10:17 AM
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Kruse Offline
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If it truly has a carb, when the engine is truly cold, take the air cleaner off and look down the carb. Then step down on the accelerator pedal. The choke should snap closed. When the pedal is pressed, you should also have two little jets of fuel that squirt down the carb (provided that this is a V8 engine). After the engine starts, the choke pull-off should open it up slightly and also have a fast idle. Choke should open slowly as the engine warms up.
Of course, the rest of the engine should be in good working condition also and the ignition system should be up to par.

Re: Carburetor Question?Fuel? [Re: Marco620] #5319536 01/11/20 10:25 AM
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JeffKeryk Online Content
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More information is needed such as hard starting, falling on its face, etc.
But here is general carb procedure:

1st - ignition tune up
2nd - fuel supply - clogged filter
3rd - start engine, allow to warm up and adjust idle mixture screws for highest vacuum

Beyond that, you have to be able to do serious carb work.
That is probably a QuadraJet which is the best carb when right; it is a complex design.
It may be a computer controlled Q-Jet, which is by far the hardest to work on.
By the way, I love QuadraJets!

Good luck.


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2001 Tundra Access Cab, 1998 Accord LX, 1968 Corvette L36 Roadster, 1965 Olds 4-4-2
Re: Carburetor Question?Fuel? [Re: jhs914] #5319828 01/11/20 02:32 PM
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Linctex Offline
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Originally Posted by jhs914
then a pull off to reduce rpm's and open the choke when the engine warms up. .


The "choke pull off" or "choke break" or also "choke vacuum break" is used to open the choke a hair (about 1/4) right after the engines starts,

so it doesn't flood out while the engine starts to warm up.

If the truck runs like crap in cold weather, the choke system is failed or not adjusted properly.

NO AMOUNT of Redline Si-1 will fix that!


"The evidence demands a verdict".
(Re:VOA)"it's nearly impossible to actually know the particular additives that are in there at what concentrations."
Re: Carburetor Question?Fuel? [Re: Marco620] #5320068 01/11/20 05:56 PM
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BEETLE Offline
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Sounds like it needs a carburetor overhaul. I had a trouble with mine on my 1984 Isuzu pickup. I had a difficulty looking for a carburetor overhaul repair kit because of the age of my truck. I ended up buying a Weber carburetor.
Well, I glad I did because it is running much much better than the original with emissions deleted.
If you are going to buy a Weber carburetor watch out for FAKE Chinese made ones. The original Weber carburetors are made in Italy.


84 Isuzu P/up - Fram PH3950 - Valvoline 10w-30
08 Ford Escape - Napa 31348 - Motorcraft 5w-20
98 Ninja 250 - Wix oil filter - RotellaT6 - 5w-40
Re: Carburetor Question?Fuel? [Re: Marco620] #5320139 01/11/20 07:00 PM
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ragtoplvr Offline
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If he has a heated air cleaner, whis is common on cab and throttle body injection then make sure the hoses are intact and it is functioning. 86 was the last year for carb I think. If carb it needs a new float and alcohol resistant accelerator pump and float needle. The choke pull offend vacuum advance in distributer will be bad too. Alcohol vapors kill the diaphrams.

Rod

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