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Vacuum Leak stock 2.8


happilymarried

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1984
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Ford
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Okay, so the weather is cooling down around here (though it's Phoenix, so that means 40s overnight), and it's causing my bone-stock 84 BII to idle HORRIBLY first thing in the morning. I've been driving it with a known vacuum leak for months now 'cause I just got tired of looking for it, but I'm giving this thing to my sister in a couple months (if it makes it that long) so I'm trying to get it running a little better.

For the first few minutes, it lopes like crazy at idle, and it has a really hard time getting off the line. I've had to develop quite a sensitive right foot to give it just the right couple of thrusts as I let the clutch out to get it moving. By the time I drive 25 miles to work and get off the freeway, it's usually idling great (though the idle sometimes gets stuck pretty high after such a long trip). It still has a hard time coming off the line and I really have to rev it up a bit before letting out the clutch to keep it from stalling.

Under the hood, I can clearly hear the carb sucking air. Is it possible the leak is from the gasket between the carb and the intake? I think I read something once about using silicone gasket sealer in addition to the gasket there, but I know I didn't do that when I rebuilt the carb about 6 months ago. On top of that theory, the whole vacuum system is old and brittle and surely not working to it's full potential.

I'm sure everyone will recommend a Duraspark conversion, but this thing already has 240K on it, so I'm really just trying to keep it alive for as cheap as possible.

Thoughts anyone???
 


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unoleisu

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I had a "mechanic" friend of mine rebuild my 85 2.8 BII engine awhile back. Among many other things that were not right, I had that same problem. The new gasket on the carb to intake didn't quite cover all that it was supposed too, and resulted in a vacuum leak you could hear. It was on the passenger side, if I remember correctly. I ended up using RTV silicon sealer to re-pair it. I found that I had to build up a wall or dam to fill the gap that wasn't covered by the (apparently incorrect) gasket. It worked fine after that.
 

kimcrwbr1

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You can isolate the vacuum leaks best by using a length of vacuum hose put one end up to your ear and search around with the other. Check around all the gaskets, fittings, hoses it works for exhaust leaks also. Stick the end of the vacuum line in the carb while it is running so you know what to listen for. Fix the leaks properly if your leaking between the carb and the spacer get a new spacer and surface the base of the carb. Pull off the carb and remove the throttle position sensor glue a sheet of 180 grit sand paper on a flat piece of plywood and slowly in a circular motion slide the carb around until the whole surface is the same color. dont use alot of pressure and keep it nice and flat dont gouge it. Put a new gasket between the carb and the spacer and slowly snug it down dont torque on it. Do not use silicone anywhere near the carb it will leak again unless your just going to sell it and dont care as long as it happens to someone else. Get some vacuum hose and replace any hoses that are hard or cracked. Once you get all the vacuum leaks fixed make sure everything is plugged in then erase the memory and reset the computer by disconnecting the battery for 1/2 an hour and run it for another 20 minutes at medium speeds and while it is still hot run the codes.
 

The_Dealer

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Duh!
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duraspark it
 


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