Can the throttle linkage be sticky?

This does no good for a car that’s been parked overnight. It’ll start after sitting for an hour. I think fuel isn’t making it to the float bowl, not that it isn’t making it from the float bowl into the carburetor.

And manners.

Can’t speak to your truck’s specific configuration, but on my truck

1 . Remove air cleaner ass’y
2. Remove fuel bowl covering plate from top of carb (4 screws, fiddly job).
3. Fuel bowl is then visible; I still have to use a step ladder to see the fuel level.

After just removing the air cleaner ass’y I can pretty easily see the fuel squirt from the accel-pump outlet near the top of the venturi when operating the throttle; but if a person had never done this before they might not know where to be looking. Not a whole lot of fuel comes out, and the fuel is hard to see, transparent.

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To lean over to get closer?

Is it enough to smell?


For me to get high enough to see down into the fuel bowl. 4WD truck’s engine is fairly high off the ground.

I don’t recall smelling gasoline when checking the accel pump that way. I know which exact holes the gas comes out, so pretty easy to see visually.

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Gas doesn’t squirt with cold engine but does with war engine? Weak fuel pump and/or bad accelerator pump.

Does your carb have a small round glass window? If so, jiggle the car and see if there’s gas about halfway up that window. (The Aisin carb on my 1979 Toyota truck had this feature.)

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I have those in mind, but I replaced the fuel pump 534 miles ago. I replaced the accelerator pump 1,302 miles ago. I hope they haven’t failed already.

You misunderstood my question. @Mustangman told me that there was fuel in my float bowl. I asked him how he would know. I know about the sight glass. It’s hard to see, shadowed as it is.

jiggle? Do you mean crank the engine to work the fuel pump to fill the float bowl? How many revolutions does that take? I’ll try to do it with my breaker bar.

No, just jiggle/wiggle left-right with your hands on the fenders while you are looking at the sight glass. In some cases it makes it easier to tell if there’s fuel halfway up that glass disc.

It’s so hard for me to see it already. @Mustangman said fuel should last in the bowl for an hour, so I have to work the fuel pump to fill it.

I don’t see where you checked the choke pull off? Did you check it? How to check choke operation. Engine cold, step on gas pedal and see if choke closes, it should close. Start engine. Step lightly on gas pedal for moment only and let up. Check to see that the choke is partially open. If it remains fully closed, the choke pull off is bad.

BTW, clean the sight glass with a q-tip.

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Yes. What I can test works.

I can’t do this. When I try it stalls, at least when it’s cold.

I’m not sure what @Mustangman means. Once filled, the fuel in the fuel bowl should remain there for considerably longer than an hour when the engine isn’t running. Over time the fuel in the bowl will evaporate somewhat, but none should be leaking out.

My carb doesn’t have a a sight-glass to see the fuel level. But when I have trouble seeing the fluid level in those plastic bottles like for the coolant or the brake fluid, clutch fluid, or even just the wind-shield washing fluid, I get best results by shining a bright flashlight through the side. Works best at a time when it is somewhat dark.

A poor ground connection can cause the throttle cable/housing to corrode and become gummed up

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All it takes is a light jab, just enough to release the linkage. Even if the engine stalls, you had vacuum to the choke pull off so it should open the choke about 1/4 the way so you can still check it. If it doesn’t open, then that is the reason it stalled, no air.

Another thing you might try is to start the engine, then manually pull the choke open a little. Then operate the throttle and see if it stalls then.

I don’t understand. When I turn the engine off, the choke is open, stays that way until I press the gas pedal the next day, when it’s cold, then it closes, without starting the engine.

I thought of installing a manual choke, but didn’t.

That is what it should be doing…

The choke should be wide open with the engine at normal operating temp, but the choke can not set it’s self once the engine is cold again until you tap the gas, tapping the gas pedal when the engine is cold is what sets the choke and the fast idle cam, the choke closes to reduce the intake of air and allows a fuel-rich charge to be drawn into the cylinders when the cold engine is started. As the engine warms up, the choke is gradually opened automatically by heat, and you need to tap the gas pedal once again for the idle to drop back down to normal… If the choke stays open when the engine is cold, it will not be rich enough to idle correctly or stay running on a normal day… The reason to push the pedal to the floor once, twice or whatever is just to put some extra fuel in the intake to help the engine start faster/better/easier, but when you do the pedal pump thing is when the choke sets… technically you can tap the pedal just enough to set the choke and fast idle without spraying fuel down the carb/intake…

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OK let’s try again. First, when the engine has warmed up, the choke will be fully open and stay that way until it gets cold AND you activate the throttle. The throttle is holding the choke open because it is a step up to open the choke and it can’t take the step until the throttle is open enough for the fast cam to rotate. You do not need to step on the gas several times, it is designed to work with a single push of the gas pedal and let up.

This is an old video made by Rochester Carburetor Company. They were a large carburetor manufacturer back when all cars and trucks used carbs.

Now as soon as the engine starts, the air pressure inside the intake manifold goes from atmospheric pressure to a high vacuum. Even though the engine is still cold, full choke will add too much fuel. The choke must be opened slightly. This is done by a vacuum actuator, but friction by the throttle linkage will not allow it to open. This is why you have to step on the gas just enough to release that friction.

The most common problem is the vacuum actuator getting a leak in its diaphragm. In the video, he called this the vacuum brake diaphragm. See at 5:31 in the video.

IIRC, the choke pull off on a Toyota uses a two circuit design but it has been awhile since I worked on one so I have forgotten exactly how it works, but I seem to remember that it also has a pice of linkage that would freeze up and you had to lubricate it and work it by hand to get it free again.

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The reason why the engine stalls when you step on the gas when the engine is cold is because the secondary choke pull-off isn’t working.

When you step on the gas when the engine is cold, the spring in the thermal choke pull-off forces the choke plate closed.

That’s the round black plastic part on the side of the carburetor.

When you start the engine, the primary choke pull-off slightly opens the choke plate.

If you step on the gas while engine is still cold, the secondary choke pull-off opens the choke plate more, and lets the choke plate return back to the just open position when you let off the gas.

If this doesn’t occur, it’ll cause the engine to flood and stall out.

Then as the engine runs, the thermal choke pull-off slowly opens the choke plate to full open as the spring inside heats up.

So, make sure these events occur as described when the engine is started cold.


From the original question -Can throttle linkage be sticky. YES…But it really shouldn’t be. The ONLY times I’ve seen the actual linkage being sticky was when someone decided to lube it. After a while the lubricant they added to the linkage now starts collecting dirt. This dirt is causing the linkage to stick. And then they clean it and lube it again to start the cycle all over. Car linkages are a DRY linkage. Clean it with a spray carb cleaner and then let dry. DO NOT add any lubrication.


To add to Mike’s comments. If the linkage is “sticky’ it will likely keep the carburetor open, ie engine will continue to run at higher RPMs. Clean all linkage connections, choke linkage, and pivot/shaft points. The ‘spray lube’ needs to be cleaned off.
Though will not address your choke and accelerator pump, return spring might need replacing.

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