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Carb trouble 81 4.9L

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Old 10-17-2013, 09:07 PM
mshefty mshefty is offline
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Carb trouble 81 4.9L

I have recently acquired an '81 F-150 with a 4.9L inline with a one barrel on it. It has some vacuum leaks I am tracking down as well as some other issues. My main issue right now is that sometimes my truck will start just fine and drive for about 7-8 miles and when I get back in to start it up after about 10-15 minutes the carb is flooded and wont start. After it sits for a while it fires right up. What would cause it to flood out after turning off? The carb is a brand new Holley less than two months old.
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Old 10-17-2013, 09:18 PM
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what model of Holley do you have on the truck? I have nearly an identical setup, 81 F150, 4.9, fixing all your vacuum leaks would be issue number one, and then getting the carb properly tuned would be the second thing. It sounds like it is set up too rich, the choke is helping it run while cold, but during warm startup, it floods itself. im not a carb expert, but thats what i am reading...
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Old 10-17-2013, 09:59 PM
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My 80 F150 with the 4.9L/300 does that same thing if I even breathe on the throttle pedal before re-firing it during cooler weather. The electric choke cools off enough to go back to full choke, but the engine is just warm enough that it doesn't need the choke to start.
I have tinkered with the choke, but setting it lean enough to prevent the warm-ish re-fire problem results in harder cold starts, so I just adopted the practice of keeping my foot well away from the throttle pedal during these times. That, and the habit of keeping something handy to wedge the choke open, should I accidentally touch the throttle pedal before it starts.......
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Old 10-18-2013, 07:29 AM
1986F150six 1986F150six is offline
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Welcome to the forum, mshefty!

Rogue Wulff is right on. I still believe you might want to check your choke adjustment. You mentioned that you replaced the carburetor two months ago. I bet the temperature has cooled significantly during that time span. Here in the south, it is not uncommon to have to adjust chokes 4X a year [change of seasons]. Where are you located?

While chasing vacuum leaks, look closely at the two bolts which secure the carburetor to the intake manifold [or EGR adapter]. They tend to loosen over time and the new gasket may have settled. A 1/2" wrench works nicely.

I included a link to a thread which might be of assistance.

http://www.ford-trucks.com/forums/11...ent-101-a.html
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Old 10-18-2013, 08:34 AM
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sometimes when putting in a brand new carb. you have to tap the side of it with a hammer (ballping)
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Old 10-19-2013, 12:00 PM
mshefty mshefty is offline
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Thank you for the responses. I wound up having to rebuild the carb and now it is 90% better. Now off to the vacuum leaks. Does anyone know where I can get a complete set of vacuum lines and hoses? I am looking for the hard lines that come off the vacuum tree on the front of the engine with all of the connectors.
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Old 10-21-2013, 02:01 PM
1986F150six 1986F150six is offline
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Originally Posted by mshefty View Post
Thank you for the responses. I wound up having to rebuild the carb and now it is 90% better. Now off to the vacuum leaks. Does anyone know where I can get a complete set of vacuum lines and hoses? I am looking for the hard lines that come off the vacuum tree on the front of the engine with all of the connectors.
Take a look at this thread... it has all you are looking for regarding replacing vacuum lines.

http://www.ford-trucks.com/forums/12...uum-lines.html

Last edited by ctubutis; 10-21-2013 at 07:27 PM. Reason: Link to Page 1 of the thread, not Page 2
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Old 10-21-2013, 04:34 PM
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Quote:
Originally Posted by Rogue_Wulff
My 80 F150 with the 4.9L/300 does that same thing if I even breathe on the throttle pedal before re-firing it during cooler weather. The electric choke cools off enough to go back to full choke, but the engine is just warm enough that it doesn't need the choke to start.
That's why Ford was smart enough to use a hot air choke system, and why I encourage everyone to stick to the Ford carburetors when possible. The hot air choke will only choke the engine when it is needed, and only comes off when the engine is ready for it.
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Old 10-21-2013, 07:01 PM
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Originally Posted by LARIAT 85 View Post
That's why Ford was smart enough to use a hot air choke system, and why I encourage everyone to stick to the Ford carburetors when possible. The hot air choke will only choke the engine when it is needed, and only comes off when the engine is ready for it.
It has the factory electric choke, with the hot air system as well. Heck, the engine/carb are full stock.
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1980 F-150 300 I6, C6 & 9" rearend. Cummins 5.9L/ NV4500 5 speed swap in the works
1974 F100 Ranger XLT 390, C6 3.25 axle. Dad bought it new.
1983 Mazda RX7 1.1L Rotary.
1984 CRX 35 MPG go kart
1995 Mazda B2300 (undercover Ford)
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