Carburetor Question?Fuel?

Messages
4,100
Location
Kansas
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.
 
Messages
2,787
Location
USA
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.
 
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Messages
394
Location
North Florida
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.
 
Messages
4,815
Location
Kansas
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.
 
Messages
4,482
Location
Los Gatos, CA
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.
 
Messages
10,000
Location
Waco, TX
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!
 
Messages
59
Location
USA
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.
 
Messages
1,896
Location
missouri
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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