1972 f100 carb problems?
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1972 f100 carb problems?
Think lm having some problems with my carburetor.My truck has a motorcraft 2100 carb . The automatic choke was changed over to a manual choke kit by previous owner. The problems Im having : When i first start the truck(cold) I choke the carb till the engine is warm of course this makes the engine idle high and the engine runs smooth (normal) . After the engine is sufficiently warmed up and I open the choke fully this makes the engine run very rough. If i put it into gear it will stall unless I partially close the choke.This keeps the truck running but it makes the idle way to fast. I have checked for vacuum leak hoses etc. seem to be good .Adjusting idle speed just makes it idle faster.Adjusting mixture screws dont seem to make a difference what so ever.The truck runs great driving at speed but runs poorly at traffic lights and when driving slowly.also ignition timing looks ok....HELP...........Think i need a new Carb???
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From: Saskatoon, Saskatchewan
You probably have checked to make sure the choke hooked up properly and the fast idle is all the way off and not sticking . If it is on even a little bit it may speed up the idle and you will not be able to set your idle screws. 
Last edited by fomoko1; Sep 11, 2004 at 11:40 PM.
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No the fast idle screw is backed off and the choke cable is operating properly.As far as a vacuum leak there are only a couple of places it could leak .The truck does not have a booster for the brakes and only has a couple of vacuum hoses.Have you guys heard of the carburetor itsself having an internal leak? The local auto parts store can order a new carb for me for 113.00 plus core sounds pretty cheap unless you guys know of someplace cheaper.Just thought i would try all other possibilities as I have heard people say that rarely is a carb really bad.
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From: Sacramento California
Originally Posted by ant truck
Think lm having some problems with my carburetor.My truck has a motorcraft 2100 carb . The automatic choke was changed over to a manual choke kit by previous owner. The problems Im having : When i first start the truck(cold) I choke the carb till the engine is warm of course this makes the engine idle high and the engine runs smooth (normal) . After the engine is sufficiently warmed up and I open the choke fully this makes the engine run very rough. If i put it into gear it will stall unless I partially close the choke.This keeps the truck running but it makes the idle way to fast. I have checked for vacuum leak hoses etc. seem to be good .Adjusting idle speed just makes it idle faster.Adjusting mixture screws dont seem to make a difference what so ever.The truck runs great driving at speed but runs poorly at traffic lights and when driving slowly.also ignition timing looks ok....HELP...........Think i need a new Carb???
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Think i found the problem. got some carb cleaner and checked for vacuum leaks i found that when i sprayed around the throttle rod that goes all the way thru the carb on both sides the rpms shot up like crazy.must have a vacuum leak there. Would this be significant enough to cause all these problems.can the carb be repaired there .I dont think most carb kits would have these parts to seal the throotle rod.
thanks again...
thanks again...
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From: Sacramento California
Yea those can wear out, if i was you just get a remanufactured carb.There like $110 at autozone.
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Sounds like it's running lean. Did you check vacuum advance for leaks or working order.Vacuum hose must come from carb only to dist.Vacuum Advance only. Not from manifold. Check intake manifold for Vacuum leaks.
Tighten carb base & manifold bolts. Some carb models have a vacuum choke opening Diaphragm for the choke butterfly when the engine start. If this is bad it will not open choke this maybe why it has the choke changed to manual. ''Until this Diaphragm is replaced'' it will still suck air= vacuum leak unless the port was pluged. This is on top, back 1/2 of carb, 3 screws holding cover.. Another place that will suck air is inside choke housing if not pluged when changing too manual choke. Add all this to warn throttle shaft bore holes.Plus adding to this a bad power-valve. One of or all maybe your problem. my 2 cents
orich
Tighten carb base & manifold bolts. Some carb models have a vacuum choke opening Diaphragm for the choke butterfly when the engine start. If this is bad it will not open choke this maybe why it has the choke changed to manual. ''Until this Diaphragm is replaced'' it will still suck air= vacuum leak unless the port was pluged. This is on top, back 1/2 of carb, 3 screws holding cover.. Another place that will suck air is inside choke housing if not pluged when changing too manual choke. Add all this to warn throttle shaft bore holes.Plus adding to this a bad power-valve. One of or all maybe your problem. my 2 cents
orich
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