my truck runs great with no problems when it's warm.......why does it bog when it's cold....i have to press the gas pedal ever so lightly or else it will die on me....as soon as it gets to operating temp, i can hammer the gas no problem.
why would it do this?? or is this normal?

 

I don't know what year or what engine, but I am going to assume it has carb, and if it does, it sounds like the choke is not working/adjusted correctly.

 

Mine does the same - no choke plate. Get the choke working properly and all should be OK

 

it has electric choke. and before i start it i pump the gas once and the choke plate closes, and the truck starts great and idles higher (which is normal i think when the choke is on) but as soon as you touch the gas the choke turns off and the choke plate opens wide......does that mean my choke is not working???

 

It means it's not adjusted correctly. If you have the type that is a large round black piece on the side of the carb, all you have to do is loosen the three screws that hold it in place, and turn the round plastic piece. Most of them have "richer" and "leaner" written on the side with arrows. You need to turn it in the "richer" direction, or the direction that gives more pressure to close the choke door.

It may take some experimentation, since you can go too far, and then it will tend to lope and run rich if the choke stays shut too long.

 

and if that piece has rivets instead of screws, do i need to drill them out and replace with screws?

also, so there is no way to turn the choke off when sitting in the truck, it should just gradually open on it's own?

 

Yes, if there are rivets, they need to be drilled out.

If you turned the choke off, it would slowly go back shut and flood the engine out. If you have the factory setup, they usually ran the choke off the alternator. It only gets voltage when the alt is turning, which means the engine is running. This prevents the choke from opening if you happen to leave the key in run too long without starting the engine. Other OEM's ran the power for the choke through a oil pressure switch to prevent the same thing from happening.

If you have an aftermarket choke, most people run it to a hot wire in the fuse box so it's on any time the key is in run.

 

i's sorry i meant, if i'm in the truck and touch the gas pedal the choke plate shouldn't open wide suddenly??? it should gradually open on it's own?

 

It may a little bit. The choke door is somewhat tied to the throttle linkage. When you first start it, you push the gas to the floor once or twice. This moves the throttle stop out of the way so the fast idle cam can flop around. The fast idle cam makes the engine idle fast, and is controlled by the choke.

Once the engine starts running, the choke will start to open. But it does not have enough strength to move the fast idle cam on it's own, so the door will move so far, and then stop. The engine will run faster and faster until you "kick" the gas pedal. This relieves the tension on the fast idle cam, and will let the fast idle cam go ahead and flop it back to slow idle. So when this happens, the choke door may swing to full open position.

It all depends on how cold it is outside, and how you have the spring tension on the choke adjusted. It usually takes several mornings to get it adjusted correctly.

 

Cool, thanks so much for the help Franklin2

 

ok, i went under the hood and i moved the choke slighty...we'll see if that does the trick......but, as i was under there i noticed that there is a vacuum line that has broken off somewhere since the last time i was under the hood. i can't seem to find where it is supposed to be connected. it has broken off a nipple, possible a tee or a 90 elbow..the nipple is still inside the vacuum hose.
can anyone help me.....here is a link to a wepage with some pics i took.
http://www.freewebs.com/soaringshades/engine.htm

 

any help with the above problem would be greatly appreciated....here is the link again
http://www.freewebs.com/soaringshades/engine.htm

 

I am guessing you have a 351w engine. The piece on the driver's side that the hose goes to is a heat control valve. There is a passage that runs underneath the carb that exhaust runs through. This helps warm the carb up, especially in cold weather. The heat control valve opens and shuts a little door in the passageway to block the exhaust, or to let it through. In the summer it would stay blocked most of the time so the carb would not overheat.

Here's a diagram for your engine I believe.
http://www.autozone.com/images/cds/g...3d800ce68e.gif

It shows the other end is hooked to a vacuum switch that is screwed into the water jacket. This is what I would suspect, and they probably block the exhaust under the carb when the coolant gets to about 100 degrees. On or around the thermostat area on the front part of the intake manifold, there should be a plastic sensor screwed into the intake. It will have hoses running to it, and I would suspect it will have a broken nipple where your hose goes.

 

Thank you for the help, i will take another look today...it's really stupid that i can't find where it broke off of, i've looked a dozen times or so.
can you show me on any of the pics i took....where the vacuum switch might be that it broke off of?

 

i feel like an idiot cause i still can't find the broken piece that the hose came off of.