wet weather problem!! help!
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Joined: Jan 2005
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wet weather problem!! help!
hey guys, i really need some help on my 79 f150 shortie, ive been having problems with it stalling, running really rough, low idle. when the weather is damp, like rainy days, damp cold days, when snowing etc. it starts right up on fast idle runs ok for about 5 min. then the idle starts to die, then starts missing and eventually shuts off. it will restart but i have to stay on the gas at least till the temp comes up to 180. then it will run fine the rest of the day. ill give you some info on the truck. its a 79 with a 351m, 4spd. 4 wheel drive. i had the motor rebuilt by a reputable engine builder about a year ago because it was leaking oil everywhere, and the problem was there before too. he put in a truck cam, a wiend intake, and told me to install a holley 600 cfm carb vac secondaries, which i did, i had the distributor rebuilt complete tune-up good stuff too. everything is new on this truck, coil, ignition box. battery alternator regulator. ive spared no expense. ive checked the choke, working fine, its driving me nuts, i really love this truck but this problem is really getting to me. ive had it to 2 grages with no avail, they tell me its a common ford problem when you eliminate the emmision stuff, egr, etc. i do not want to reinstall that crap if i dont have to. the truck has awesome power when warm, the only time it does it is when its rainy or damp. please help thanx
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Joined: Dec 2001
Posts: 22,436
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From: Louisville,Ky.
Welcome to the forums 
You have a common problem called carb icing. It is when the cool damp air freezes up in the carburator air bleeds and restricts airflow to the idle circuit which makes it run too rich.
You need to have a working hot air system on the factory air cleaner to eliminate this. The warmed air pulled past the exhaust manifold into the air cleaner will keep it from freezing. I made a custom piece out of alumnum to fit over the header tube on my 460 to cure this problem. When the aircleaner inside temp reaches about 60 degrees, it will open the flap and let it draw in cool air from in front of the core support. Without this system, you will have these problems until the thermostat opens and warm air enters the engine compartment.
Jimmy
You have a common problem called carb icing. It is when the cool damp air freezes up in the carburator air bleeds and restricts airflow to the idle circuit which makes it run too rich.
You need to have a working hot air system on the factory air cleaner to eliminate this. The warmed air pulled past the exhaust manifold into the air cleaner will keep it from freezing. I made a custom piece out of alumnum to fit over the header tube on my 460 to cure this problem. When the aircleaner inside temp reaches about 60 degrees, it will open the flap and let it draw in cool air from in front of the core support. Without this system, you will have these problems until the thermostat opens and warm air enters the engine compartment.
Jimmy
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