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Old Oct 6, 2010 | 09:44 PM
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85Bronc0
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Question 84 F150 problem

So i recently got a 84 F150 with the 300 and 4 spd

i love my truck but it dosnt seem to run good it is running way to rich and i got back smoke coming out the tail pipe, i gave it a complete tuneup plugs wires cap rotor oil and even did the seafoam treatment and its still running rich. i know its got fire on all 6 plugs and off of idle it runs great and dosnt smoke at all when there is a load on the engine I.E. driving down the road, all the power seems to be good but the MPG sucks something fearse........

So i can either go through the carberator and all its emissions bs or go back to a 1bbl carb from an older 6.

i had a 84 bronco some years back and it had the same dizzy but a different carb on it without any problems,

so what am i missing? is it possible to get rid of the emissions and that crappy *** half wanna be efi carb setup?

i really need help with this as its my daily driver... any ideas would be greatly apprciated,,,
 
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Old Oct 6, 2010 | 10:43 PM
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8525ford
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check for a vacuum leak around the intake gaskets, their known to leak, and obviously ck all the vac lines. is that a feedback carb
 
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Old Oct 6, 2010 | 10:46 PM
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carb

to be honest i wouldnt know a feedback carb from a non feedback carb btw what exactly is a feedback carb?

i checked the vac lines already all seem to be in good working order i also checked the carb and its bolted down and so was the manifold to the head.

So i guess i could replace the carb gasket and see if that helps, the thing does have an 02 sensor. As far as i know the 02 is probably the origional 1 in the truck, could this be contributing to this issue?
 
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Old Oct 7, 2010 | 02:39 PM
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1986F150six
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Yes, regarding the O2 sensor question. The last one I bought was a Bosch and was ~$25.00. It is a single wire and is easy to install. When the O2 sensor went out on my son's 1984 F-150 w/4.9L, there was a rotten egg smell in the cab when backing up.

Another possibility is the temperature sensor located right by the thermostat. It tells the computor what the water temp. is. I had one go bad on a trip and the mileage dropped from ~20 to 12 mpg. The exhaust looked like a diesel. This part was ~$15.00 and also easy to replace. You might want to get the engine to operating temperature and while idling with the hood open, transmission in neutral and brake applied, remove the terminal from the this sensor. There should be a change in idle speed. If I remember correctly, the speed should increase. BE CAREFUL! There are moving engine parts which could cause serious injury.

If any part of the original emissions system has been bypassed, the computor will go into what is called the "safe" or "limp home" mode. The computer will direct the feedback carburetor to go rich and the timing will be locked at ~10 degrees with no advance. This protects the engine, but destroys performance and economy.
 
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Old Oct 7, 2010 | 04:32 PM
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So now my truck dosnt want to idle. what do u do to adjust that?
 
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