truck randomly stalls out, but runs perfect otherwise. help me out here

[fire-chickens]

Yes I've posted this on other forums, but i want to get answers from different opinions too.

Alright I recently installed a new Quickfuel 780cfm carb on my truck that has a BBC. electric choke vacuum secondaries. today while driving it in 20 degree weather it warmed up fine drove down the road okay but it would stumble at low throttle. as if it was trying to stall for a split second, but it accelerates fine pulls hard plenty of fuel, idles nice. timing is good all was fine a couple days ago.

now when i have it in gear or idling is when it will stall, and it doesn't spit and sputter then dies, it just dies, as if you shut the key off. to start it back up it'll just crank unless i put the pedal to the floor. would this be choke related maybe?

i checked the choke and its not sticking on, or anything. when its warm its wide open like it should be.

the truck turns over every time though. starts right up after it stalls out.

Here's my float level for reference.

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Here's a video of me shaking the truck so you can view the float level better.
http://oi57.tinypic.com/1zwezgk.jpg


Also could very cold weather affect how it runs as well? i had it out yesterday and it ran fine, mid day just above freezing, and i went out today and it was 20 degrees out, the floats and mixture screws were all adjusted when it was 45-50 degrees. i actually just had it out 15 minutes ago and it was 8 degrees out and stalled multiple times, even backfired a couple times as it was trying to stall out when going about 20mph driving through the neighborhood when im going 50-55mph it will still attempt to stall out unless i jab the gas a bit to catch it, its worse the lower the RPMS

 

[fire-chickens]

Actually after some thinking here, i really don't think its loading up and dying, i know what that's like, it would blow black smoke when re-starting it and you'd have to clear it out, turns out i was wrong when i said i had to hold the pedal down to start it, it will still fire back up immediately. it seemed worse this last time i went out it stalled more, and backfired a couple times as it tried to stall while driving through my neighborhood. I'm beginning to think its fuel related, i know the carb runs on the rich side, but it shouldn't just die instantly if this were the case. when i say idling i mean it could happen as soon as i slow down or 5 minutes after i stopped. I'm going to check my fuel pump and maybe even replace it, It hasn't been driven much the last several years and I've put 1,000 miles on it in a month now. and the engine has been in it since 1989. it doesn't make sense to me that the truck would suddenly the following day start to do this if it were float related it would sputter before it died not instantly quit. I'm almost tempted to say i felt very slight surging last week while driving it after i got the carb on it. I did go from a 650CFM carb to a 780CFM. so what do you all think?

EDIT: then again it doesn't seem like a mechanical pump would start to fail by still running and idling fine, and stalling suddently either, that seems like it would be more related to an electrical one lol ahh i hate issues like this sometimes..

I'm going to start with the easiest things and work my way down the list here, starting with the fuel filter, its clearly pretty old and it is not a transparent filter so who know's how bad it may be.

 

[chengny]

You're right, a good first check is fuel pump capacity. Pull the fuel line inlet to the carb, stick a hose on it and put the other end of the hose in a container. Have someone crank the engine for 15 seconds.

You should pump at least 16 ounces in that time.

Also watch for bubbles in the gas as it fills the container. You'll get a few at first until the hose purges. But any bubbling after that would indicate an air leak in the suction piping of the fuel pump.

Check the line between the pump for restrictions - make sure there is not an in-line fuel filter hidden somewhere that has become plugged.

 

[89_3&3]

Pull your egr valve look for breaks in the diaphragm And excessive Carbon build up use a can of ccc to clean it if any cracks or breaking in the diaphragm replace it this can cause periodic Stalling
If you have one

 

[68post]

Don't rule out any ignition problems either. A bad/weak coil , arching thru the rotor , a failing module, ...

 

[1low4x4]

Rebuilt my engine and replacef EVERYTHING. ran great, stalled out intermittently.

Was the spark plug wires. One thing I didn't change. Replaced them, never stalled again

 

[chevyk10]

Maybe I missed it but did it run fine with the old carb?


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[Splandman]

My small block was having trouble with the stock carb. A shop I was having some other work done at suggested I switch to Quick Fuel carb. Got it back and it ran better but would die at stop lights a lot. Took it in for an adjustment and it seemed to be better.

Then every once in a while it would start sputtering, wouldn't idle, wouldn't restart easily. It was driving me crazy because most of the time it ran really well. I started looking and could not find a fuel filter anywhere on the truck. I installed an in line and mine has run fine since.

Here was what started my stock carb problems I believe.