strange Idle
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strange Idle
Hello all. I'm new to the site and just bought my first Ford truck. It's an 1982 F 250 with a 300 6 cyl. I have just started doing a little work on it and have a carb question. Sometimes when i start it it idles fine and sometimes the idle drops and nearly dies. This also happens when driving down the road and come to a stop, let off the gas and and the idle drops to around 4oo and nearly dies. I rebuilt the carb and it ran great, for a bit. I did notice the hot air return going into the choke thermostat has been pinched off. Could this be the problem? The carb is a 7051sa.
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Welcome to FTE! Your choke may well be the problem. You need hot air to the choke and w/o it the choke may well not be coming fully off. And, that can easily bring the fast idle into play. So you may be idling on the fast idle part of the time and then after a hard or long run the choke may come off and the idle drop down.
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still not fixed. runs ok down the road but sometimes when i let off the gas the mufflers (straight pipes) make that popping, cracking sound and there's a strong smell of fuel (from the exhaust?).when i get stopped the idle drops and i have to feather the gas. Other times it slows to a stop just fine, smooth exhaust sounds, no idle drop. carb was just rebuilt, everything set to spec. any ideas?
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From: Northeast, OK
What we may be seeing is an intermittent vacuum leak. A vacuum leak usually makes the engine idle faster and we turn the idle stop screw out to compensate. But if the leak goes away then the engine runs slowly.
The six is bad about the bolts on the carb vibrating loose, which causes a bad leak. And all of the rubber vacuum lines are suspect due to their age. So check things out, and if you don't find a leak try spraying brake clearer around. If there is a leak the brake cleaner gets sucked in and the engine runs faster.
The six is bad about the bolts on the carb vibrating loose, which causes a bad leak. And all of the rubber vacuum lines are suspect due to their age. So check things out, and if you don't find a leak try spraying brake clearer around. If there is a leak the brake cleaner gets sucked in and the engine runs faster.
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From: Northeast, OK
Chris - Good point! I forgot that.
Rusty - You should either cap off or pinch closed all vacuum lines to see if that makes a difference. And the brake booster can leak sometimes a bunch more than others.
Rusty - You should either cap off or pinch closed all vacuum lines to see if that makes a difference. And the brake booster can leak sometimes a bunch more than others.
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will give it a try this weekend
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