Diagnosing exactly one missing vacuum hose
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Diagnosing exactly one missing vacuum hose
Hey everyone,
I haven't posted too much here as I try to search and usually lurk to gather most of my info.
I have an 1986 F150 300I6 with the infamous feedback carb and it runs well, but my gas mileage is pretty atrocious, doesn't run too crazy rich and blow smoke, but it does seem to guzzle gas. A 6 mile round trip to the gym and back 5 times, and maybe another 10 or so miles around last friday night after I filled up polished off 3/4ths of a tank.
Luckily after more detailed inspection, One and ONLY one vacuum fitting remains unattended to. Its the easiest one to see! Its the vacuum port which always seems to be a red hose in any pictures I've seen coming out of the side of the throttle body right below where the air cleaner box mounts.
I'll post pictures later if needed, but if anyone knows (as its an easy vacuum fitting to simply describe) where the hose jutting out of the top of the throttle body, right alongside the the throttle plate/butterfly, goes it'd be greatly appreciated. I think thats what is locking my timing and making it run rich/get bad mileage?
I haven't posted too much here as I try to search and usually lurk to gather most of my info.
I have an 1986 F150 300I6 with the infamous feedback carb and it runs well, but my gas mileage is pretty atrocious, doesn't run too crazy rich and blow smoke, but it does seem to guzzle gas. A 6 mile round trip to the gym and back 5 times, and maybe another 10 or so miles around last friday night after I filled up polished off 3/4ths of a tank.
Luckily after more detailed inspection, One and ONLY one vacuum fitting remains unattended to. Its the easiest one to see! Its the vacuum port which always seems to be a red hose in any pictures I've seen coming out of the side of the throttle body right below where the air cleaner box mounts.
I'll post pictures later if needed, but if anyone knows (as its an easy vacuum fitting to simply describe) where the hose jutting out of the top of the throttle body, right alongside the the throttle plate/butterfly, goes it'd be greatly appreciated. I think thats what is locking my timing and making it run rich/get bad mileage?
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Joined: Nov 2007
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From: Denver Metro Area, CO
I think what you're trying to describe is for the choke heater; fresh air comes from the carburetor area, is routed down to the exhaust manifold where it's heated, then back up to the choke housing with the bimetallic spring in it.
That hose by itself not being connected won't do squat to affect your gas mileage, just cold-weather drivability. But a sticking choke (one that's stuck (mostly)) closed could very well make for bad gas mileage....
That hose by itself not being connected won't do squat to affect your gas mileage, just cold-weather drivability. But a sticking choke (one that's stuck (mostly)) closed could very well make for bad gas mileage....
Moderator
Joined: Nov 2007
Posts: 22,415
Likes: 92
From: Denver Metro Area, CO
Cargo Master
Joined: Mar 2008
Posts: 2,573
Likes: 207
From: Washington
I think what you're trying to describe is for the choke heater; fresh air comes from the carburetor area, is routed down to the exhaust manifold where it's heated, then back up to the choke housing with the bimetallic spring in it.
That hose by itself not being connected won't do squat to affect your gas mileage, just cold-weather drivability. But a sticking choke (one that's stuck (mostly)) closed could very well make for bad gas mileage....
That hose by itself not being connected won't do squat to affect your gas mileage, just cold-weather drivability. But a sticking choke (one that's stuck (mostly)) closed could very well make for bad gas mileage....
But if the second half of the loop was missing, meaning the hot air that goes to the choke, which then makes the choke open up... this would effect your gas mileage.
Have you looked to see if the choke is opening up after the 3 mile run to the gym?
Jim
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