I have a 85 F350 w/460. Within the past few months I replaced the plugs, wires, distributor cap, and PVC valve. The truck was running fine until a week ago, I noticed that the truck was having a hard time starting (I had to give it more gas than usual). Today, the truck wasn't trying to start until I stepped all the way on the gas pedal. Once started, it idles a little low (4000rpm), and a little smoke comes out the exhaust (only at idle). Once the truck is moving/driving, it feels fine and doesn't smoke. It feels like water is in my fuel or something. What could this be? Is my carburetor starting to go bad? How do you know when it goes bad

Even with the truck warmed up, it still has a hard time starting & idling

 

You mentioned that it ran fine, until about a week ago. Has the weather abruptly changed [temp.] or did you perhaps fill up the gas tank at a "new" gas station?

It could be as simple as the choke needing a seasonal adjustment.

Perhaps something else you can think of as having changed at that same time?

 

When I first bought the truck in November, it wouldn't start. The guy said the choke was stuck open, and that's why it wouldn't start. But it never acted up after that, until now. Could that be the problem? I'm having a choke issue?

 

And yes, I go to different gas stations all the time

 

Well, I do not know where you live, so don't have a clue regarding weather changes, but I would guess that wherever you live, it has just started warming up for Spring.

If the truck had a choke problem in November, when you bought it, and "the guy" said the choke was stuck open, causing it to not start, then we must assume that an adjustment was made to close the choke, which makes the mixture rich, which is what is required for starting cold engines. Now, the weather is warmer and the mixture needs to be less rich, so the choke needs to be more open.

A properly working automatic choke makes these adjustments based on the ambient temperature, to begin with, then heat from either an electrically heated choke element or exhaust heated air which is drawn by engine vacuum into the choke housing.

Anyway, if the choke is set too rich, the engine will not want to start in warmer weather and just might smoke at first until the choke opens.

With the engine cold, take off the top of the air cleaner and look down the carburetor. Before starting, with the key off, gently press the accelerator to the floor and release. Now look down the throats of the carburetor. The choke plate should be closed or almost completely closed [~3/16" gap]. Try to start the engine. It should start at a high idle speed. If it will idle, carefully [CAUTION!!! Watch for fan blades and belts, etc.] watch the choke plate and see if it opens. After a couple of minutes, "blip" the throttle and the idle speed should drop and the choke plate should be open, fully. If not, it is either sticking or needs adjusting.

Are you following me?

 

Here's a picture with my engine turned off (the engines been sitting 1 hour). The choke is completely open now. Is this correct? I'll do the steps you told me once I get a family member here. And yes, the weather is normal (spring), but it did rain a lot yesterday

 

It appears that the choke is fully open. If you gently press the accelerator to the floor [engine off], will the choke plate close?

I can't tell by the photo... is the choke still automatic? Or, has it been converted to manual?

 

How do i know if it is automatic or manual? The is my first engine w/carburetor I've owned. Before this issue, I would push the gas pedal once or twice, turn the key, and it would start. It would idle a little rough, but only until warmed up.

I'm going to test it like you said, and report my results

 

With the air cleaner removed, so you can see the carburetor more clearly, look for the choke housing. It will be a circular shaped housing at the end of the shaft which turns the choke plate. It will have a black plastic cover with a wire attached. It may also have a metal tube [~1/4"] which is originally covered with a tan/white sheath, which acts as a layer of insulation.

If you find a cable [like a lawn mower throttle cable] attached to a lever which is attached to the end of the shaft on which the choke plate is attached, then you have a manual choke. If that is the case, the cable should pass through the firewall and go under the dash. Usually, to the right of the steering wheel, near the ash tray, there will be mounted a black or chrome pull **** which is pulled out to close the choke and pushed in to open the choke [sometimes reversed].

Tell us what you find. Your photos are helpful.

 

Ok, I think I have an electric choke. Please dont give up on me yet, we're getting closer. I had someone press the gas pedal to the floor, and release. The choke did not move at all. I did not have them start the truck yet

 

When the truck is running, and someone pushes the gas, the choke plate does not move. No matter what we do, the choke plate stays fully open. What does this mean? Is it a simple adjustment, or do I need a new carburetor.

(I tested the 1 wire going into choke housing assembly, and it is getting power)

 

I have to leave, soon, but will to finish this...

Above the red wire, you can see a screw, which pulls the ring holding the choke element. There will be 2 more screws, each 120 degrees apart. They are used in adjusting, but first, wait for the engine to be fully cold to see if the choke plate closes when the accelerator is depressed. If it does not, take your fingers [with engine off] and see if you can gently move the choke plate. If it is free and if partially closed and then springs back once you let go, then it is adjusted to lean.

At that point, try loosening the three screws [just a little]. Before moving the black plastic housing, use a marker [Sharpie] and make a mark where it is before moving [so you can always go back]. Rotating the black plastic housing clockwise should cause the choke plate to close. When cold, the plate should close to within ~1/8-3/16". Adjust to that point and gently snug the three screws. Try to start the truck and hopefully, it will fire off and idle at an elevated speed until it warms up and you "blip" the throttle. You might have to play with the adjustment, a little at a time until you find the sweet spot. I find that this has to be done seasonally.

New fuel injected vehicles do not have to do this as the computer does this for the operator.

Good luck!

 

Eddilard79,

Read the attached link... it is about a Carter YFA single barrel carburetor, but the choke function is much the same. It may help you understand what the choke does and how it operates.

https://www.ford-trucks.com/forums/1...ent-101-a.html

 

I really appreciate all your help! Wish I could buy you lunch or something

 

Thanks for the thought.