Carb Question?

[jdpritch]

On my 73 Bronco (3 on the column) when changing gears I would puch the gas and it would try to stall. It would act like if you were in the high of a gear for the speed and start sputtering and jerking. I changed the fuel filter, fuel pump, diaphram in the carb, rotor button, and distributor cap. When I crank it now if I don't give it a lot of gas it will shut off. There is some king of red float on the side of the carb that appears to be sticking. My battery also seems to be getting drained and I just bought it last week. Would the alternator be causing all of this or just part of the problem.

 

[Bully Bob]

"I would puch the gas and it would try to stall."

Definately a carb. problem....Which diaphram..? The one in the front of carb. is the acelerator pump. Is that the one you changed? (assuming stock carb.) This one is important.

Did you change all those other parts for this same "sputtering" reason..?

Again most likely a carb. float, needle-jet, or accel pump issue.

" My battery also seems to be getting drained and I just bought it last week."

Seperate issue...If your truck will make it to Auto Zone, they will test your alternator (& bat.) on the vehicle (for free..!!)

If not, take it off & they will test it (& bat.) in the store..

 

[Broncoholics]

Did you replace the fuel filter in the carb & frame rail or where ever it is?

I had a problem simular and replaced the carb and it fixed the problem. Something else to think about is do you still have points? If so maybe the condenser is bad in the distributor. If this is bad you will see signs of cutting out and no power under load.

 

[jdpritch]

The diaphram I replaced was in the front right bottom if you are standing at the front bumper looking under the hood. It is a 4 barrel Holley. The filter I replaced was the inline filter between the carb and the fuel pump. The clear plastic filter housing is already showing trash in the bottom, one of the auto stores mentioned that I may need to have the gas tank drained?

 

[Broncoholics]

Could be, how old is the gas? Bad or old gas will cause these signs.

Tanks sweat so most time adding a product called HEET will take out the water. Sounds like you have crap in yours. When I pulled my tank and looked inside I found sticks, kids toys, rocks and the pickup tube screen looked clogged.

I set the screen in Coke and it looked new the next day. Might be worth the check. Afterall the rear tank is only held in by one bolt and a few hoses. To drain I always disconnect the fuel line at the fuel selector switch and drop it in a spare tank. Then blow into the tank with my mouth and cause pressure and this will push the gas down the line and cause a sipen. If the tank is full you might not need to blow into the tank, gravity will do the trick.

 

[jdpritch]

Thanks. I will give it a shot. The gas is from Friday. Will these things have anything to do with the red plastice thing sticking on the side of the carb?

 

[Broncoholics]

Not sure do you have a photo of the red thing?

 

[jdpritch]

I will try to get a picture of it, it is on the left side of the carb and it may be called a fast idle vaccuum something??? When you press the throttle something lifts this red thing up and it seems to stick. Probably not much help but I will try to get a picture tonight.

 

[jdpritch]

It is the fast idle cam...

 

[Seabronc]

That cam hold the throttle plate slightly open while the engine is warming up. If it is working right it will let additional gas in thru the transition circuit to richen the mixture. Putting your foot into it should cause the choke plate to open up and allow more air into the carb which draws more fuel via the venturi jets.

Basically, after the engine starts fuel is normally feed via the idle circuit untill you press the accelerator to start moving. It sounds like the idle circuit is clogged and not supplying enough or any fuel. By putting your foot into it, you allow the main metering circuit to supply fuel which it shouldn't at idle. There are 5 circuits for supplying fuel in your carb;

1. The idle Circuit (two small pin holes just below the throttle plates)

2. The transfer circuit (two long slots that are just above the throttle plates when the throttle is closed adds fuel when transfering from idle to cruise on the main metering circuit).

3. The main metering circuit (the main jets and air bleed holes which supplies fuel via the venturi)

4. The Power valve circuit (which enrichens the main metering circuit)

5. The Accelerator pump (which gives a shot of extra fuel when you punch it)

You should probably take the carb off and check that the throttle plates are set properly and that the idle holes are clear. You could go as far as a carb rebuild kit, but keep in mind the kits don't address problems caused by wear of the moving carb components. Some times it makes more sense to replace the carb rather than rebuild it.

I changed the first line. Teach me to respond when tired :blush: .

Good luck,

>-

 

[jdpritch]

Thanks so much for the input guys. I had the carb cleaned and a new kit put in yesterday...I will see if that solved it today.

 

[Bandit]

I had a similar problem,replaced the carb and it soon started again,problem with mine was the tank had 30 years of varnish and garbage in it from sitting and rusting,I tried flushing it with fair results,but ended up replacing the tank with a 23 gallon model...end of problem.

 

[jdpritch]

I had a similar problem,replaced the carb and it soon started again,problem with mine was the tank had 30 years of varnish and garbage in it from sitting and rusting,I tried flushing it with fair results,but ended up replacing the tank with a 23 gallon model...end of problem.

28549[/snapback]

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Bandit, You hit the nail on the head...so until I get a tank I am out of commission.