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Old 03-07-2011, 08:59 PM
79str8six 79str8six is offline
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carb poops out? why i ask. 300 6 cyl.

i have a 1979 ford f250..
just figured out charging issue thanks to FMC400.

anyway....here goes...

my truck will idle fine or even drive(if your light..super light on gas pedal)..but when you give it gas fast i will stall out..makes for very diffuclt start being i have a manual 4 speed,it does have a manual choke...the only way i found works better is to have choke half open all the time. This cant be right..it still will wanna bog/stall with choke at half its just a whole lot better than with choke off.

recent carb kit thrown in it (carter 1barrel)....stil does it.
could or is there an adjustment on carb that may be out of wack??
300 cyl.

need advice
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Old 03-07-2011, 09:43 PM
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wyckedcombo17 wyckedcombo17 is offline
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Is the engine fully warmed up and only operating on 1/2 choke? The engine still might be a little cold. My engine runs like a turd when its cold (0* and below) until it warms up.

Otherwise it could be a mixture adjustment. Are you sure your float is adjusted right? Mixture screws adjusted right? Power valve ruptured?

How much vacuum are you getting at idle?

Also, what color are your plugs?
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Old 03-07-2011, 10:34 PM
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fmc400 fmc400 is offline
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This is due to a lean condition, either because of a vacuum leak, or faulty accelerator pump.

With the engine off, look down the throat of the carburetor and actuate the throttle. You should see a nice stream of gas shoot against the venturi. If not, check that the accelerator pump and lifter link are properly assembled inside the carburetor.

Check for a vacuum leak by idling the engine and spraying for suspect areas with a can of carb cleaner spray, and listening for a jump in the idle speed. If this happens, the area you sprayed is leaking vacuum. Common areas include the carburetor base gasket, cracked vacuum hoses, and the brake booster. Sometimes you have to lean out the engine such that it just barely idles so that you can hear the jump. A vacuum leak will also be revealed by measuring the vacuum level at idle as wyckedcombo has suggested.

The reason choking the engine improves the problem is because it enriches the combustion mixture, which helps compensate the lean condition caused by the weak accelerator pump or vacuum leak.

Quote:
Originally Posted by wyckedcombo17 View Post
Otherwise it could be a mixture adjustment. Are you sure your float is adjusted right? Mixture screws adjusted right? Power valve ruptured?
Just a side note: Carter 1-barrel carburetors do not have a power valve; instead they have a single metering rod.
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Old 03-08-2011, 04:44 AM
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Another possibility is that something is blocking your main jet or the passageway to it. Especially with a 1 barrel, if any trash/dirt/piece of old gasket, etc. blocks or partially blocks it will make the motor go lean.

You really have to make sure all the passages in the carb are clean. Today's gas is really bad about gelling if it sits for very long, so when the carb is apart you have to make sure you clean everything using compressed air to blow out all the little ports to make sure it's absolutely clean inside.
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Old 03-08-2011, 08:47 AM
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Originally Posted by Talltruck View Post
You really have to make sure all the passages in the carb are clean. Today's gas is really bad about gelling if it sits for very long, so when the carb is apart you have to make sure you clean everything using compressed air to blow out all the little ports to make sure it's absolutely clean inside.
Great advice. When you rebuilt the carburetor, did you do the full job (completely disassembling the carburetor, soaking metal parts in Chem Dip, spraying them clean, and blowing out the internal passageways with compressed air once dry)?

Anything short of that will often cause more issues than there were to begin with. The reason I ask is because when I hear the term "throw a kit in it," I think of the carb simply being sprayed down with a can of spray cleaner and closed back up with new seals. That won't work.
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Old 03-08-2011, 08:47 AM
 
 
 
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