Alright so hear me out. I'm 20 years old and I've gone to a tech school and have held a few jobs in the business. Problem is, none the guys I work with know a damn thing about carburetors. And at my local "cruise nights" (mainly people sitting in chairs) alot of guys are running EFI or don't know anything about what's under the hood of their car except that there's shiny stuff under there. I have books, tried reading online but that can only go so far. I have no real way of learning this stuff and never really worried about it until my car won't start. Recently I ran out of gas and poured in what I had left in the shed to get me to the nearest station. Ever since then it's been giving me problems. I figured I just had bad gas and that it would just burn out. It's been two weeks and no change. It won't start first thing in the morning, but after cranking and cranking, it finally starts, then dies. I do this 4 or 5 times, then she's fine. She runs great all day, starts fine after that the rest of the day. But then the next day, it gives me problems again. I have a 350 with an edelbrock carb. I seem to get gas when I pump the pedal, I have no vacuum leaks and the plugs look fine. I'm thinking the bad gas messed up the choke because it's fine when it's hot, so I sprayed cleaner in the carb and put lucas fuel treatment in the tank. I don't know where to go from here, I could really use some help here!
A good basic source on automotive technology in general is Hillier & Pittuck's Fundamentals of Motor Vehicle Technology. The chapters on carburettors are simple and easy to follow. Only then go on to sources pertaining to a specific model or type of carb. First of all, though, make sure your carb problem isn't actually a timing or ignition problem.
So first thing in the morning pull the air cleaner off and manually open the throttle. Check to see what the choke is doing, then see if there is gas inthe carb when you hit the throttle. Have seen the chokes get lazy and not close as they should usually because the retainer screws have come loose on the choke spring housing. If you ran out of gas the other day you may have sucked some dirt into the system. You running an electric or manual pump? With filters?
For a 20 year old, you sound like one of the older guys on here... I'm sure Mr. Carbking will be on soon to give you a hand with your carb problems... I only know Holley Carbs...
you could have particles in the jets and idlers. but if i didnt read the part were you mentioned you were low on fuel my immediate thought would be the choke not being in adjustment. im assuming you dont have a manual choke. automatic chokes are basically like a barometer, they have a coil spring that contract when cold and expand when hot. thus moving the choke for you. at starting the choke should be about 1/8"-1/4" nearly shut. then once it warms up it will open up to full.(they sometimes are electronic also but work on the same idea. to adjust them, they usually have 3 set screws on the sides of the plastic cover. sometimes they are marked with hash marks "lean, and rich", you can move the cover which will move the spring, hit the throttle if its not moving sometimes that frees it up. there is a process to properly starting the old cars. everytime you get in the car you should mash the pedal down ONE TIME, this both sets the choke(if it was shut off open), and it also activates the accelerator pump to push some fuel into the chamber to give you your initial starting fuel. sometimes the pumps get weak and you gotta pump it a few times, if this is the case its time for a rebuild.(in fact if you put modern fuel in it, it could have eaten it up) basically it works like a syringe, when you push the accelerator down if forces fuel out of some jets and it mixes with the air being sucked in. at the same time the accelerator pump is pushing fuel in, your butterfly valves are opening and letting the pistons suck the fuel and air in. this makes the engine run faster and moves more air into/through the carburetor chambers. this air moving through the carb then creates a siphon effect and keeps the engine running at that consistent speed through the jets. once you let off the pedal, the butterflys shut and thus stopping the flow of air through the carb, and then you must once again start the process in order to get back up to RPM. i think that explains it in simple terms? here: http://www.youtube.com/watch?v=XOxxS1EMphU
I'm going out on a limb and saying it may not be a carb issue. It sounds like the fuel is draining out of the line and back into the tank. You could have a torn valve or some gunk stuck in the one way check valve(s) inside the fuel pump. All the fuel in the line drains back, the little fuel in the carb mostly boils off and there isn't enough to get the engine to fire long enough for the fuel to go all the way back up the line, prime the fuel pump and then get it into the engine on what little is left in the carb.
GasolineJunkie, ask yourself this, do you really want to learn about carbs or do you want to learn about fixing your carb? As a ex New Yawka I'd like to help you with the understanding and learning " carbs " but only if you really want to, and yes I used to teach this class as well as dyno tuning, and performance engine building. You need to first learn about my old uncle from the old country, Italian Physicist: Giovanni Battista Venturi. You can't undersatand how a carb works without understanding the "Venturi Principle". Google it my friend and learn. Do you know that the very first carb on a motorcycle was made from a soup can? That's not a joke and it is true, a soup can. My advice is if you really want to learb how a carb, well carbs, is to get a single barrel carb of any type generally from a small 4 stroke engine and identify all of the parts AND how, why, what they do. A motorcycle carb is a great place to start like from a single cylinder Honda or similiar carb. The round slide that moves vertically up and down is the same principle as the throttle blades or butterflys in your automotive carb. If you can do that, you can understand your carb or any other automotive carb whether side draft, down draft, 1,2,3,or 4 barrels as well. Again, all carb theory starts with uncle Giovanni, class dismissed.
I had the same problem last week, ran out of gas and it did the same as yours. Check the inlet fitting to the carb, some crap got past the the filter, went to carb. Also, check the float valve for sticking. Diavolo gave you some good advice too!
Sounds like the carb picked up up some crap. I ran into this as well . 1st, take the carb off and set it on a flat surface. Using needle nose pliers unhook tha accel. pump linkage and pull the rod out and set it aside. Do the same thing to the choke lever at the rear of the carb. Unscrew the top of the carb and gently lift it off . Set it upside down. Look at both sides of the main body for anything floating or gummy looking stuff in the bowls. Put a finger over the spring from the accel. pump and dump the gas out. Pull the air adjustment screws out. Use carb cleaner and spray every opening, crevice, crack , jets, you name it, spray it and spray the air adj. too. Put it back together. I'd go about 1 1/2 turns on the air mixture to start with and go from there for best idle. Replace rubber fuel line and filters and go from there. I made the mistake of having the same deal with mine and the only way I got it right was to do everything above...and keep using the gas additives to fight the ethanol. Should take you about 30 -45 minutes taking your time. Good luck...
What kinda worked for me was to get a reman carb from the autoparts store and look at it and take it apart while reading the carb book for that particular model--it was a q-jet. And the book was rochester carburetors by Doug Roe (former gm engineer). This way you can physically see in 3 dimensions what is being discussed in the book versus trying to visualize all those concepts in your head. It helped me emensely. The reman carb will be rather expensive vs. a junkyard carb, but it will be clean; This may be important overall especially if you want to do this inside. Winter is coming. i find i can learn better in a cozy enviroment, but that's just me. A salvage yard carb may be dirty and have a gassy smell. And then after that, of course there are numerous boards, such as here, where you can bug people with questions. And numerous videos on the net. Don't worry too much if you really want to learn.
befor you pull the carb off it could be as simple as some crud in your needle and seat in the fuel inlet of the carb. When you ran out of gas, along with the gas you probably sucked a lot of stuff out of your gas tank, Many tanks have a sintered brass filter at the tank pick up. they are effective is straining a lot of junk out of the tank, but not real fine stuff. and once your sucking out the dregs of the tank, you will likely pull a lot of crap with it. So here is what I would do first. remove the fuel line from the inlet side of the fuel pump, and withthe gas cap removed, blow some low pressure compressed air back toward the gas tank. This will clear the line and the filter and the area around the filter of fine crud and rust. The pull the fuel pump, and take off the bottom chamber, many have a fine brass screen between the inlet chamber and the pumping chamber. Many times this will become clogged with gunk also. You can also check the function of the check valves in the pump to make sure they are functioning and clean. Now disconnect the line from the pump to the carb, and make sure it is clea and free. Then pull the needle and seat assembly from the carb inlet, and assure it is clean and the needle moves freely. The needle is closed by the float but if there is debris it may not open when the float drops and will not allow fuel into the float chamber. Then reconnect the lines and pump, and with the coil wire pulled, have an assistant crank the engine withthe starter. Direct the fuel line into a suitable container, a clear soda bottle works fine. While the assistance cranks the motor count pump strokes as the fuel flows into the bottle, with 12 strokes you chould have between 8 and 10 ounces of gas in the bottle. If that check out you should be good to go. If you still have problems, then you can disassemble the carb and check the internal stuff. But before you dig into the carb, make sure you are getting gas to and through the pump. Also if the crud is keeping the needle open, the residual pressure from the pump can flood the carb as gas can keep flowing after shut down. Check your dipstick for gas smell in the oil. Gas flowing after shut down will get past the rings and can get into the oil pan.
Edelbrocks are simple carbs. They only ask a few things of their owners before they start with temper tantrums. 4.5 psi fuel pressure cleanliness Both of those are easy to correct Sucking the tank dry = sucking dirt Old gas out of the shed = adding more dirt varnish and crap to suck up You'll find edelbrocks for $40.00 on CL that just need a cleaning NO parts.
Wow I'm really surprised I didn't get any "read a book numb nuts" kinda responses! Those links are really good reads, and yes I wanna learn about how these things work so I'm not totally lost when something goes wrong, and also I'm genuinely curious about how things work. I like the idea of getting a cheap re-man carb to take apart with a book in hand to learn the ins and outs of it. As far as mine goes, I'm gonna try changing the filter and cleaning it better, but I have a feeling it's gonna have to come apart to really clean it properly.
i learned about carbs and how they work buy going to a swap meet buying an old crappy carb off a VW and rebuilding it....lol then i my neighbor gave a old AFB i got a repair manual and tore into it
Here is a point I would like to stress for anyone following along, and I'm quite certain I can say Jon, { carbking - and yes he is } would agree on. It is always good to start with a evaluation of the carb's " base plate ". If you have or find excessive play in your throttle shafts and the base plate, this will need to be addressed before continuing. All the new gaskets, jets, metering rods, cleaning, and adjusting etc., etc. will not make up for and correct excessive play in the throttle plate, meaning you will forever be chasing your tail with driveability and tuneability issues. Generally bushings can be installed and precision align honed/reamed and or new oversize throttle shafts to give you a new throttle shaft to base plate fitment. Too tight a fitment and you can easily end up with the throttle stuck open as the parts heat up and expand and bind. Too loose a fitment and you again be chasing tuneability and driveability issues- forever. The reaming will also have to be in alignment with each side of the throttle plate or you probably won't get the shaft to even go in and or be able to get the butterfly's to close properly, a real mess now. This procedure is best left to a professional or someone with the skills and correct tools for the job, and yes it can be done by some at their home garage or shop.
Ok I've been driving it around the past few days and it's been fine. Now today she's acting up again. I cleaned the carb and I have a new filter on it. I've got gas to the carb but she won't start for anything now. Before it take a few tries but then be ok. Now I get in the car, she starts up ok, then dies almost immediately and won't start up again. I really don't know where to go from here. I don't think the timing is off because the distributor is nice and tight and is where it's been since I've had the car. I'd really appreciate some help here i'm totally lost.
The Jalopy Journal
