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| Sudden Loss of Ability to Idle https://slantsix.org/forum/viewtopic.php?t=10767 |
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| Author: | Daddiojoe [ Wed Oct 27, 2004 7:47 pm ] |
| Post subject: | Sudden Loss of Ability to Idle |
As of this morning, my truck will not idle under 1000 RPM. It felt kind of like a vacuum leak, so I replaced the vacuum hose to the distributor, and made certain that all the outlets that I wasn't using on my Carter BBD were plugged with good store-bought plugs. I thought that cured my problem, but it hasn't. This is a super six on a 71 D100. Carter BBD, with Pertronix ignition. 727 transmission. The air mixture screws at the bottom of the carb are screwed out to about three turns. The gas filter isn't the problem, I checked it and even tried to run w/o it so as to eliminate it as a suspect. The symptoms are the same whether the air cleaner is on or off. Symptoms don't change after the engine heats up. I had it running fairly well this afternoon, but went on an errand tonight, and couldn't keep it running. Carb has been rebuilt and adjusted in approx. May. Engine itself rebuilt and installed in April. What seems strangest to me is that this happened suddenly. As always, your help would be appreciated. Thanks, Joe |
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| Author: | Pierre [ Wed Oct 27, 2004 9:16 pm ] |
| Post subject: | |
Check the intake/exhaust to head gasket, if this is burnt away then it creates a vac. leak right at the manifold. Also carb base gasket. |
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| Author: | Slant6Ram [ Thu Oct 28, 2004 5:23 am ] |
| Post subject: | Another check |
check for clogged PCV valve or clogged port in base of carb. |
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| Author: | Craig [ Thu Oct 28, 2004 11:12 am ] |
| Post subject: | |
I've had that problem more than once on those BBD's. The idle fuel pickup tube fell out so one side is not getting any fuel at idle. Remove the venturi cluster and look. There should be two of them, one for each side of the carb. I can't remember how I made it stay in but it did not have a choice. 
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| Author: | Daddiojoe [ Thu Oct 28, 2004 7:42 pm ] |
| Post subject: | Thanks, everybody |
The four bolts that hold the carb down were way loose. How the heck did they get that way? Should have remembered to check them. I'll also check the idle fuel pick up tube. It seems to be running a lot better now. Thanks for your help, as always, Joe |
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| Author: | Craig [ Thu Oct 28, 2004 10:01 pm ] |
| Post subject: | |
Well, if it idles now then your tubes are probably OK. When one or both fall out, there is NO fuel at all available to the idle circuit and transfer slot. It will not run unless throttle is open enough to pull fuel out of the main fuel circuit (venturi). |
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| Author: | /6tom [ Fri Oct 29, 2004 3:07 pm ] |
| Post subject: | are these idle tubes called called cover-venturi |
in an exploded diagram of bbd? it sounds that you have solved for me a problem that suddenly appeared about 2 weeks ago and I could have written the symptom postings. I've changed the plugs, retimed the spark, cleaned the carb, disassembled the carb (but not the cover/venturi ), set the valves, and said to myself 20 times it sure acts like its not getting idle gas. It backfired a few times as a warning or a cause. Thanks slant /6 brother. tom 78 d150 /6 bbd od 4sp 10 year owner 70 dart custum /6 bbs auto 20 year owner slant 6s can run forever. |
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