Autolite 1100, 1 barrel carburetor questions & answers. Below you will find questions we get from our customers and our suggested solution.Carburetor Shuts Down on Turns
Mike, My autolite 1100 shuts down when making a sharp right turn, as if the gas shuts off and the engine dies. Can you help with a solution.
F1 (1100) carb had a vent push rod that was actuated by the accelerator pump diaphram arm. vent is open at rest or idle & closed when throttle up or driving. Durning its life rebuilders redesigned the carb & eliminated the vent push rod?? I prefer the rod be there myself. The vent opening inside the air horn is on the opposite side from the pump diaphram. On hard turns,to one side, it could slosh fuel from vent tube down the venturi. Recomend he also check float level (1″ for rubber float and 1 3/32″ for brass float) and maybe lower it a small amount. If he has a rubber (nitrophyl) float maybe replace with a brass float. Nitrophyl float should weight be under 10 grams.*Can the plastic vent rod be left off the 1100
We have done it without any problem.my autolite 1100 leaks down if you let it sit 15 min or so and it blows black smoke when you start the engine after it sits 15 min or so and also it surges at cruse speeds
1100 & 1101 can’t leak down through the main body like some carburetors can. Not knowing the condition of the carburetor (recent carb overhaul done correctly or not overhauled recently) ther are several possibilites. Incorrect float seatting or bad float (rubber/nitrophyl float s/be 1″ and brass s/be 1 3/32″) If it is the old rubber/nitrophyl float I would replace it with a brass float. Float problems would cause the fuel in the resivoir to percolate on hot soak and drip into the intake manifold, because of a high float level caused by a heavy float or incorrect seatting. It can also leak fuel from the pump discharge port for the accelerator pump because of a missing check ball weight or chech ball not seatting well on its seat. Some carbs can percolate because of there enviroment. (closed small engine compartments like vans) Can try a thicker flange gasket which acts as a thermal barrier to the carburetor as the engine heat over heats the carb on hot soak.
Choke wasn’t opening. Hot air tube not hot.
The heat is pulled up through a vacuum passage inside the choke housing. The vacuum is supplied from the bottom of the carburetor via the intake, then travels to the choke housing. You should be able to blow air through into the bottom hole and hear it come through to the choke housing.
In this case the hole was plugged up at the bottom with carbon.
Engine Pops & Sputters When Turning Off
This problem is most likely dieseling, which means there is un-burned gas in the intake and it fires from the heat when turning off the engine. Automatic transmission type of engines might have a dashpot mounted on the carburetor. Make sure this is adjusted correctly. See adjustments. Running rich – Lots of things could cause this. Look at your spark plugs. If burning black then you are too rich. The same things that cause richness can also cause flooding. See flooding below. A gas smell coming from the engine when idling also indicates it’s running rich.
Dies when pressing on gas. Does not start without priming
Turn the engine off. Look down the carburetor and pump the gas. If you don’t see a squirt of gas, then the accelerator pump circuit is faulty. See this page for pump information: When starting your car an extra squirt of gas is necessary from the accelerator pump circuit. After running the vehicle turn it off and look down the carburetor. Is gas dribbling out of the main discharge. If so, then gas is being siphoned by the engine. That would be the main discharge leaking.
When fuel is coming over the top, or out of the vent, or from the throttle shaft, then you are getting too much gas. Some causes not in any order:
Fuel pump pressure too high.
Needle & seat not closing completely. Test the needle & seat.
Fuel leaking around the seat and not through the seat.
Float sticking – pin may be worn.
Body warped – very common.
If the vehicle sits for months at a time, the the gas may have turned and coated the inside of the carburetor with varnish.
The gas tank is dirty and after rebuilding, or replacing the carburetor dirt flushes up to the carburetor. This can happen even with a filter. In this case the there may be dirt in the needle and seat. Try tapping on the fuel inlet part of the carburetor (not so hard you put dents in the carburetor). That might dislodge any dirt, otherwise take the top off and see if there is dirt on the bottom of the float bowl. Inspect the needle and seat for dirt or damage.
Watch a video about the Autolite 1100 Flooding Troubleshooting
Hesitation or Bog
I have a 65 mustang 6 cyl 200. I replaced the carburetor, and the modulator valve. Also installed electric pickup (removed points). The problem is after it’s hot and sets turned off for a few mins it stalls when select to drive or reverse. Does not want to take gas. The engine is original never rebuilt with 88K mi. Any suggestion as to what I’m missing or adjustments to look at.
My educated guess would be that the problem is gasohol.
You know that gasohol makes the engine “work harder” to do the same amount of work, hence generates more heat, and that it also boils at a lower temp than “pure” gasoline (the definition of a “viscous cycle”).
Now, think about how those Ford 1100 accel. pumps “hang over” on the outside of the carburetor — they are absorbing more heat than the fuel mass inside the bowl is! So while the engine may not be getting hot enough to boil the gasohol in the bowl, it might just get the comparatively tiny mass of fuel in the accel. pump hot enough to percolate like crazy.
Solutions: use ethanol-free fuel if available; reduce engine temperature (lower heat range plugs & thermostat, bigger fan and radiator, retard the timing, electric fan that continues to cool after engine shut-down) or a heat shield under the carburetor.
What else it might be:
Fuel level in bowl too low to allow accel. pump to “draw” from the bowl (usually due to the misconception that setting the float lower than specified will “stop the carb from flooding”);
Accel. pump leaking externally due to warpage in pump cover (common);
Incorrect size check balls (or correct size balls not seated properly) in accel. pump intake and discharge positions;
Inadequate accel. pump jet diameter for gasohol (I always oversize ’em .001 – .002″).
What Makes Gas Drip From Venturi?
Fuel is being sucked into the carburetor throat.
- Check ball at main discharge may be leaking. Tap the check ball lightly to seat it. Test the accelerator pump before putting the carburetor back on the car. See this page on how the pump works.
- Check ball and/or check weight is missing.
- Wrong gas cap. Be sure cap is vented. You can test this by loosening the cap and driving the car to see if the venturi drips.
- Least likely is the fuel pump pressure is too high. Should be about 4-4.5 lbs. Flooding will generally occur in this situation.
- There are some vent tubes and idle tubes you need to be sure are open.