While changing the ECG valve earlier today, Dad and I noticed the hose seen in my hand just sitting about only connected on one end. Can anyone tell me where this hose attaches?

The truck in question is a 1985 F150 with the 300 inline 6. It is a base model 4x2 with no a/c if that matters.

 

Aircleaner - maybe

 

Do you have this style aircleaner?

 

Not trying to sound mean or anything, but could you take a better picture or two of the vacuum lines and the emissions label on the hood of your truck? We've got to be able to see the label too so we can know it's going in the right spot.

I see that it's coming off of a T fitting though, and the location makes me think it's part of the EVAP system on your truck. But I can see the T-fitting going from the outer bowl vent and charcoal canister up next to the carb, and it has all the lines hooked up right to it, so the loose line you've got can't be for the EVAP.

I'm going to agree with the others though and say that it came off of the air cleaner when you pulled the air cleaner or the snorkel off the carb. Does the truck run okay with the line unhooked?

What kind of stuff does the line attach/run to?

 

No offense taken. As for what air clear is on the truck. Its this one:



Here is the hose routing chart from the truck:



The hose starts at this control box (circled in black) on the passenger side fender:



Then it goes to the "T" fitting circled in black. I am holding the unattached other end of the mystery hose:



From the "T" fitting, a wire goes off towards the engine.

As for how it runs without the hose attached, I'm not certain, as dumb as that sounds. Let me explain. After failing smog this morning, I was told that the EGR valve could very easily be the culprit as well as the source of the rough idle. Dad and I took off the air cleaner to look at the EGR valve. It looked terrible and possibly original, so we replaced it with one sourced at O'Reillys. With the air cleaner already off and before we removed and/or disconnected the EGR valve, we noticed the hose in question lying about with one end disconnected. When we drove home from failing smog, the truck ran great. After, changing the EGR valve the truck starts fine but doesn't want to stay idling for very long. It does not just shut down, rather it slowly dies. For background, last weekend my friend, a mechanic, rebuilt and reinstalled the carburetor. I have no idea if I'm making this part up, but i wonder if the carb needs adjustment since it was reinstalled and set up with the old and suspected bad EGR valve. I cannot confirm if the hose was attached before taking the air cleaner off or not. My buddy is going to try to come by this weekend and take a look at it. In the mean time, i thought maybe someone here might know as well.

 

I think that control box is the MAP sensor - MAP on your diagram.

 

It probably goes to manifold vacuum on your "vacuum tree" under the carb on the passenger side. - a metal post with 4 or more air nozzles sticking off of it. Look at that thing and see if there is an uncovered unused air nozzle that looks like it is missing its hose.

 

Correct - that control box is the MAP (Manifold Absolute Pressure) sensor. The truck won't run right (too rich) if it isn't properly plumbed up.

 

When your friend comes over, study your emissions label and look at how all those hoses are routed in your engine bay.

I'll be willing to bet that it hooks from the MAP sensor to the intake manifold vacuum tree just below the carburetor on the pass. side like shown in the diagram.

The nice thing about emissions labels and vacuum line routing, is that it can help you troubleshoot your engine.

Pay attention to color codes on the label when tracing your lines. Yellow is the Manifold Air Pressure (if I remember right?) sensor and air cleaner stuff and that WILL affect your motors running ability if not hooked up. Green is the Exhaust Gas Recirculation system that kicks in when your cruising at say 55 and the motor is all the way warmed up for better MPG/emissions. The dotted lines are your Evaporative Emissions system where it draws in your gas fumes so they don't leak into the open air.

We have a post in the tech tips and tricks sticky that tells you what all these acronyms on the label mean:

Ford Truck Enthusiasts Forums - View Single Post - Vacuum Diagram Acronyms

Some of the acronyms are missing on the list, but it should give you a general idea.

 

I was typing up my response and hit enter and then I see yours.

^^^ What those two guys said!

 

Great minds think alike . Your answer was better than mine, actually.

 

That would also cause you to fail smog (whatever that is) as it would run a little rich. The MAP sensor (Manifold Absolute Pressure) tells the computer basically the load on the engine. You have the luck of having one of the last efforts of trying to meet emission standards with a carburetor. Make sure you crankcase vent system is in good order and clean, and if in doubt, do a fresh oil change and even new plugs.

 

Also, when the MAP fails, the engine will ping badly under light to moderate load.

 

With your assistance, I was able to locate what I believe to be the port where this hose is supposed to attach. I could not see it at first as it was hidden in the dark behind another hose. I circled in the place in the picture where I attached the hose. It still does not idle correctly, but I think i know why that is and I will start a different thread for that.